OJotncU litniocraitg SItbrarg atltata, Sitat fork CHtM\STRV LlBRAlii Date Due CORNELL UNIVERSITY LIBRARY 3 1924 050 977 366 Cornell University Library The original of tiiis bool< is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924050977366 GROVES A¥D THORP'S CHEMICAL TECHNOLOGY , GHEMISTBY APPLIED TO ARTS AND MANUFACTURES VOL. I. FUEL CHEMICAL TECHNOLOGY OR CHEMISTRY IN ITS APPLICATIONS TO ARTS AND MANUFACTURES EDITED BY CHARLES EDWARD GROVES, F.R.S. EDITOR OF THE JOURNAL OF THE CHEMICAL SOCIETY AND WILLIAM THORP, B.Sc. ^ WITH WHICH IS mCORPOBATF.D RICHARDSON AND WATTS' CHEMICAL TECHNOLOGY VOL. L FUEL A^D ITS APPLICATIOI^S E? j; MILLS, D.Sc, r.p..S., AND p. J. ROWAN, C.E. (Edited by CHAKLES E. GROVES) SEVEN PLATES AND 607 OTHER ILLUSTRATIONS PHILADELPHIA P. BLAKISTON, SON & CO. 1012 WALNUT- STREET 1889 & .'^'J/Z^f ^s^iJSRARV HHiGc^l PEEFACE. This volume is the first of a new edition of " Chemical Technology," founded on that written by Richardson and Ronalds, and subsequently much enlarged and in great part rewritten by Richardson and Watts. As the German Technology of Dr. Knapp was taken as the basis of the original, Richardson and Watts' work has long been familiarly known as " Knapp's Technology." The law of progress, to which all industrial processes are subject, however, causes any work on Technology to become out of date in a few years, and this applies in a special manner to the very large class of operations which are closely connected with Chemistry. For nowhere has the extraordinary activity in all departments of knowledge which has been witnessed during the last thirty years been more marked than in the domain of Chemistry, and this has necessarily borne fruit, not only in the modification of old methods, but also in the invention of new processes, and in the introduction of more perfect methods of research. On this account it has been deemed advisable to issue a new edition of this Technology, or, rather, a new work on Chemical Technology, in which the historical portions of the original have been retained, but supple- mented by a full account of the most approved and successful methods and appliances introduced of late years in the application of Chemistry to the Arts. This work wUl be divided into sections, of which the most important are — Fuel and its Applications. Textile Fabrics. Lighting. Leather, Paper, &c. Acids and Alkalies. Colouring Matters and Dyes. Glass and Pottery. Oils and Varnishes. Metallurgy. Brewing and Distilling. Sugar, Starch, Flour, &c. The present volume treats of Fuel and its Applications generally ; its special employment in various branches of chemical manufacture being reserved for detailed consideration in the volumes devoted to the special subjects enumerated above. The questions connected with the constitution and use of fuel form no b VI PKEFACE. exception to the general course of advancement, and there is no doubt that both the nature of combustion and also the economical distribution and utilization of heat are more clearly apprehended by many than they were formerly. In fact, the progress in this department has been such that this volume, although founded on the earlier one, is really a new work, and this remark will necessarily apply also to the volumes on Lighting, &c., which will follow. Where possible, historical matter from the old edition has been retained, especially on account of its great value in the case of processes or appliances which are capable of being made the subjects of patents. It is not too much to say that many patents owe their existence to ignorance concerning what has been done in the matters of which they treat ; and manufacturers would often find historical infor- mation of great use if it were available without laborious searching through Patent OiEce records. The subjects of the manufacture of gas for illumination, methods of lighting by oil and gas, the manufacture of candles, the distillation of coal, shale, wood, and peat, with the secondary products obtained there- from, miners' safety-lamps, and other lamps used for lighting, have been excluded from this volume, which is consequently restricted to the con- sideration of Fuel and its Applications. Where possible the duty obtained from the fuel in furnaces has been quoted, and general rules have been given by which the duty of any stated furnace or heating appliance may be estimated. In the case, however, of furnaces used for some special process — as, for instance, chemical furnaces —it is not easy to obtain this information, as their duty is generally expressed in terms of the chemical product which they turn out, and the thermal elements of the chemical processes other than combustion which are carried out in them must in these cases be taken into account. Particulars of these instances must therefore be looked for in the volumes dealing with the chemical manufactures in which such furnaces are employed. What Sir I. Lowthian Bell has done in this respect for the process of making pig-iron remains, however, to a great extent to be done by others in the case of other industries. In the Preface to the former (1856) edition, the Author stated that a method of smoke prevention, although much wanted, had not then been discovered. That cannot be said now, for not only has the idea of " con- suming smoke " become obsolete, but also the requirements of complete combustion are so well understood that only through carelessness need the bulk of industrial firing with solid fuel be other than practically smokeless. The use of gaseous fuel, moreover, is well known to be a perfect method of smoke prevention, which even carelessness in manipula- tion cannot vitiate to a serious extent. Exhibitions of appliances for preventing smoke which have been held of recent years in Glasgow, Manchester, and London have done much to popularize the use of suitable methods. The figures representing the output of coal in Britain and other PREFACE. VU countries show the enormous development which has taken place in the fuel industry all over the world. At the same time it is creditable to the skill of mining experts that the larger volume of mining work is (in this country, and presumably in others also) conducted with a greatly lessened percentage of accidents. The labours of the Royal Commission on Accidents in Mines in this country, and of Mining Commissions in France and Germany, have within the last few years thrown needed light on several matters con- nected with coal-mining, and especially on the part played by coal-dust in explosions in mines, and this will necessarily result in further improvement in the methods of working coal. On the continent of Europe, methods of cleaning, washing, and classi- fying coal have reached a great degree of elaboration and refinement, and these methods are gradually afiecting the practice in Britain, in spite of the smaller monetary value of coal per ton in this country. In the manufacture of coke, there has been great development of methods of coking, by which the waste gases are collected for the extrac- tion of their ammonia, tar, &c. The gases from blast furnaces using coal and from gas-producers have also been made to yield these products, and great advance has likewise been made in the perfection of methods of extracting ammonia in shale distillation. The nature of coke has also been made the subject of close examination by several chemists and metallurgists — in particular by Sir I. Lowthian Bell in this countiy, and by Mr. F. P. Dewey in America, the latter of whom has furnished valuable contributions to this volume. Undoubtedly the greatest development in the application of fuel which has taken place since 1856, however, is to be found in the spread of the use of the gaseous form of fuel, and in the introduction of appliances for its use in manufacturing and in domestic operations. Regenerative furnaces — and e.specially that of Siemens — have intro- duced a new era in methods of firing and heating on an industrial scale, and have been a powerful means of spreading intelligent knowledge in the use of fuel, which has produced marked effects in domestic heating and lighting operations also. Methods of producing gas for various purposes, as well as appliances for utilizing it in different operations, have conse- quently become numerous. Attention has been turned to the forms of furnaces, the nature of flame, the transmission of heat, the calorific value of fuels, and many kindred points, with an activity previously unknown, and it will easily be understood that the mass of information which has thus been acquired is far too great for the limits of any one work. It is hoped that this volume has succeeded in presenting such a view of the subject as will be valuable generally, and, from the copious references given, specialists will be enabled to -study in detail the particular branches with which they are concerned. Besides well-known technical institutions, many friends of the Authors have placed valuable information at their disposal, amongst whom may ft 2 Vlll PEEFACE. be mentioned the Institution of Civil Engineers, the Iron and Steel Institute, the Institute of Mechanical Engineers, and the Mining Institute of Scotland, by special permission of their respective Councils ; Dr. Bond, Mr. J. Constantine, Mr. E. A. Cowper, Messrs. Crosby Lockwood & Co., Mr. T. Fletcher, Mr. J. Mactear, Messrs. Massicks & Co., Mr. Henry Simon, Messrs. Verity & Co., Mr. W. Whitwell, Messrs. Wright & Co., and others, to all of whom the Authors and Editor desire to tender their sincere thanks. August 1889. CONTENTS. Introduction ... i Fuel . ... 2 Wood. . . 3 Water contained in Wood . ■ 3 Specific Gravities of Different Woods . 6 Ash of Wood . . ... 7 Turf or Peat 1 1 Formation of Peat . ... 1 1 Water in Peat 14 Ash of Peat ........ . 14 Elementary Composition of Peat ' . . . 19 Heating Effect of Peat . . . . . . .20 Coal 21 Formation of Coal . . 21 Brown Coal or Lignite . 24 Water and Ash of Brown Coal 24 Geology of Pit Coal 28, 39 Chemical Eolations of Coal . . 3 ■ ? 33 Microscopical Examination of Fuel . . 35 Area of Coal Beds ... 44 Annual Production of Coal 45 Analyses of Cannel Coal . . 47 Ash in Coal . . .... 32, 47 Composition of Coal . . . 52 Composition of Anthracite . . 57 Fire-damp ... eg Fire-damp Indicators ... . . .70 Coal-dust and Explosions in Mines . .... -75 Gases occluded in Coal . . ... 82 Spontaneous Ignition of Coal . ... . . 83 Effect of Heat on Fuels 86 CONTENTS. Wood Charcoal Manufacture of Wood Charcoal Charcoal Burning in Meiler or Mounds Charcoal Burning in Heape General Remarks on Mounds and Heaps Charcoal Burning in Kilns Yield of Charcoal Properties of Charcoal Ash and Specific Gravity of Charcoal Ked Charcoal or " Charbon Roux " . Moulded Charcoal . Peat Charcoal Lignite Charcoal .... Coke Carbonization of Pit Coal Desulphurization of Coke Coal-washing Machines . Yield of Coke . Nature of Coke Porosity and Specific Gravity of Cokes Coking in Heaps Coking in Ovens .... Blast-furnace Value of Coke . Comparison of Coke writh Charcoal Gases from Coke Ovens . Tar from Coke Ovens 90 94 96 100 105 107 109 no 1 12 I'S 118 119 119 123 125-140 140 J43 I4S 161 162-192 192 197 200 202 Distillation of Feat 203 Artificial or Patent Puel, Bric[uettes 208-226 Gaseous Combustibles Waste Gases from Blast Furnaces .... Composition of Blast-f arnace Gases Comparison of Coal and Coke in the Blast Furnace Gas Producers . Recovery of Ammonia and Tar from Coal and Gases Composition of Producer Gas Natural Gas 226 227 232, 248 239-248 250-275 275 278-285 286-293 Liquid Puel Methods of using Liquid Fuel Results obtained by the Use of Liquid Fuel Calorific Value of Liquid Fuel . Calorific Value of Oil Gas 293 300-316 317-327 328 329 Minor Fuels 330 CONTENTS. XI Theory of Heat ... Eelative Value of Fuel . Calorimeters . Absolute Heating Effect Pyrometrical. Heating Effect Pyrometers Formulae for the Absolute Heating Effect Flame Nature of Flame . . . . Temperature and Propagation of Flame Luminosity of Flames .... On the Application of Fuel ■ Prevention of Smoke Gas Firing ..... Chimneys Chimney Gases Chimney Draught . Forced Combustion Domestic Heating The Open Fire-place The Siemens Coke-gas Fire Application of Gas as a Source of Heat . Stoves Gas Stoves Tests of Gas-burners Efficiency of Gas Stoves .... Gas Cooking Stoves .... Tests of Gas Cooking Stoves . Bunsen Mixers .... Exit Gases and Soot Heating by Means of Hot Air Hot-air Stoves Hot-blast Stoves Principles of Hot Blast Heating by Water and Steam Emission of Heat by Hot-vfater Pipes . Heating by Steam Heating by Hot Water .... Ventilation ..... Application of Fuel to Vaporization . Lav?s of Transmission of Heat Application of Carnot's Law to Boilers . Analysis of Boiler Performance Examination of Combustion Temperatures Transfer of Heat through Boiler Plates . PAGE 331 332. 353-365 334 • 336 339, 348 340 358 365 365 366 370 373 373 375 • 378 379 382 • 384 • 389 • 389 399 399 403-413 413-422 414 423 427 431 433 433 434 439-449 450-470 470-478 478 485 492 494 495 496 497 499 501- Xll CONTENTS. Vaporization . ■ ■ ■ ■ S°3 Cornish Boilers . ... . • 5°^ Locomotive Boilers . . 5°7 Marine Boilers 5°^ Prevention of Smoke from Boiler Fires ... S" Mechanical Stokers . . . . 515-534 Gas-fired Boilers . 535-583 Results obtained by Gas Firing as applied to Boilers . . 547 556, 565, 569 Evaporation .... Evaporation in Open Pans Vitriol Concentration Evaporation of Brine Evaporation of Brine by Gas . Evaporation by Steam . Evaporation by Multiple Effect The Yaryan Evaporator . 583 583 584 58S 587 587 590 592 Distillation Stills Rectifiers Coffey's Still . Destructive Distillation of Wood Heating Gas Retorts 595 595 597 600 607 609-618 Drying . Drying Wood Malt Kilns 618 62: 621 Ovens for Baking Bread 624 Brick and Porcelain Eilns Gas-fired Kilns Hoffmann's Brick Kiln . Guthrie's Kiln Expenditure of Fuel in Kilns . 625 626 629 631 634 Purnaces Blast Furnaces Cupola Furnaces Silver Lead Furnace Reverberatory Furnaces . Salt Cake Furnaces Plus-pressure Furnace Efficiency of Coal-fired Furnaces . Utilization of Heat in Puddling Furnaces Metallurgical' Furnaces Coal-dust Furnaces 636 637-642 642-651 651 652, 660 652-657 654 ■ 657 659 662 664 CONTENTS. xm Gas Furnaces 664-692 Economy of Gas Furnaces . ... . . 665 Regenerators or Reonperators . .... 668 Blow-pipe Gas Furnaces 674 Gas Cupola Furnaces 676 Siemens' Furnace with Reversing Regenerators ... . 678 Siemens' Modified Furnaces ....... . 681 Action of Flame in Furnaces . 683 Gorman's " Heat Restoring " Furnaces 685 Ponsard's Gas Furnace . . . 688 Radcliffe's Furnace with Continuous Regeneration 689 Gas Annealing Furnace . . 691 Gas Firing of Brewers' Coppers .... 692 Gas Muffle Furnace . . . . 692 The Practical Effect of Fuel . 692 Relative Values of Fuel for Warming . 695 Efficiency of American Coals in raising Steam . . 702, 705 Admiralty Investigation of the Efficiency of Coals in raising Steam . 702 Relation between the Composition and Value of Coal . . . 706 -Defects in the Methods used for estimating the Calorific Value of Fuel . . 706 Important Features of Steam Coal . . . .710 Tests of the Practical Value of Coals . . 711-732 Analytical Tables of Various Kinds of Coal and Other Fuel 733-769 APPENDIX. On the General Principles of Coal Washing 771-777 INDEX . 779-802 ILLUSTEATIONS. I. BorLER Furnaces : — Anderson's " indicatoi* diagfram " for boilers . Chanter's grate Cornish boiler Diagram of combustion temperature curves Howard's furnace for coking firing- . Locomotive boiler .... Marine boilers ■ . St. Kollox boiler, with external furnace . Waggon-shaped boiler, with external furnace . Wye Williams' smoke-consuming furnace II. Briquette Apparatus: — Apparatus for Bessemer's patent fuel Apparatus for Chagot's artificial fuel Apparatus for manufacture of Wylam's patent fuel Apparatus for Warlich's patent fuel Furnace for briquette manufacture at Blanzy III. Calorimeters and Pyrometers ; — Calorimeter (Thompson's) in action Camelley's water-current pyrometer, diagram of Siemens' electrical pyrometer, diagram of Thompson's calorimeter, apparatus for Weinhold'B calorimeter,' diagram of IV. Charcoal Making : — Apparatus for obtaining charcoal and tar Appearance of interior of meiler during charring Charcoal kiln Charcoal meiler complete with cover Diagram of action of charring in heaps . Diagram of principle of charcoal making Heap for charcoal burning . . . Meiler for making charbon roux Feat charcoal kilns for Vignoles' steam process Peat kilns of Oberndorf in Wurtemburg . Plan and section of stationary meiler foundation Plant for making moulded vegetable charcoal Schwartz charcoal kilns Sectional view of horizontal meiler . Section of upright or vertical meiler PTG. 339 355 341 • 34° 348 •342 343. 344. 345. 346 • 349. 350. 351 ■ 352. 353. 354 • 347 131. 132 ■ 130 114-121 122-126 127-129 219 220 . 221 217, 218 222 32. 33 42, 43. 44 . 41 24, 25 34-40 28, 29, 30, 31 17 V. Chemical Furnaces : — Apparatus for distilling peat . . . . Apparatus for distilling wood . Belgian furnace for zinc ores Combustion arrangement in Jones and Walsh furnace Distilling furnace for sulphide of mercury Furnace for lead ore Halliday's retorts for distilling sawdust, &c. . Mactear carbonating furnace ... Oven for charring peat .... Pan and roaster furnace for salt-cake Pitch ovens Plus-pressure furnare . ... • 478 475 ■ 566 550 • 474 ■ 563 • 476 • 549 ■ 477 551. 552 • 503 553-555 PAGE 498 515 506 500 513 507 508, 509 514 S'S 512 219, 220 216 209-211 213, 214 214, 215 335 342 343 334. 335 344 102 97 100 93 98 97 9S 110, III 117, 118 116 99 112 114 103, 104 91 92 609 607 664 653 607 663 608 653 608 654 6ig 655 XVI ILLUSTRATIONS. V. Chemical Fcrnaces {continued) Befining furnace for silver . . . . Eeverberatory furnace for coal Hichardson'd furnace for silver lead ore . Richardson's ore-hearth St. Bede chemical furnace VI. Coal Washing :- Barclay's coal-washing: anparatus . Berard's coal-washing machine .... Diagram illustrating coal washing- .... Diagrams of piston coal-washing machines Grant, Ritchie & Co.'s coal-washing machine . Kerr and Mitchell's coal-wushing apparatus . Liihrich coal-washing plant at Bochum . Mackworth's coal purifier . ... Meynier's coal-washing machine .... Plan and section of coal-washing sluices at Commentry The same, at Felessin Sheppard's coal-washing machine .... 564. 565 547' 548 S44-546 ■ 529 556-55^ 56,57 ■ 54 . 607 45-48 62-765 66,67 58,59760 55 ■ 53 49.50 51)52 . 61 VII. Coking:— Aitken coke ovens . . . ' . Appolt coke ovens .... . . . Bee-hive coke oven employed in France . Belgian coke ovens Coke ovens of Seraing, Belgium Copp^e coke ovens . . . . . , Davis breeze oven Diagram showing imperfectly coked coal Furnaces and condensing apparatus for peat distillation . Heap for making coke, section of ... . Heap in process of making,, section of ... . Jameson coke ovens ... . . . , Ordinary bee-hive coke ovens ... . , Otto's coke ovens .... . . , Pemolet coke ovens ....... Siemens' breeze ovens Silesian closed coke oven Silesian open kiln for coking stuall coal . . . . Simon-Carves' coke ovens Square coke ovena, elevation and plan of . . . VIII. Evaporating and Distilling Apparatus : — Boutigny's holier ... ... Coffey's still as formerly made Copper stills with worms .... DerosBc's still Dorn's distilling apparatus Modern form and arrangement of Coffey's apparatus Opeli pans for brine evaporation .... Open pans for concentrating oil of vitriol . Open steam evaporator heated by pipes Pan furnace for evaporating to dryness Steam evaporator with double bottom Surface evaporator for weak liquors Surface evaporator of steam pipes . Triple-efnt apparatus .... Vacuum pan . . Yaryan evaporator 96197 • 77 78. 106-110 86,87 92. 93. 94 . 68 111-113 69 70 98,99 79-85 102-105 • 95 89, 90, 91 • 73 74. 75. 76 100, lOI 71,72 • 450 ■ 470 465-467 469 IX. Fire-damp Indicatoks : — Action of Liveing's flre-damp indicator . Ansell's fire-damp indicator ..... Apparatus showing artion of fiie-damp indicators . Apparatus to show diffusion of gases Diagram of effects of flre-damp on safety lamp flame Maurice's fire-damp indicator .... Pieler safety lamp 471-473 453. 454 451, 452 458. 459 456 ■ 457 460 ■ 455 . 462 . 461 463. 464 14 13 663, 664 652 651 637 656. 657 13I1 132 129 774 125 136-138 138, 139 132, 133 130 128 126 126, 127 13s 182, 183 175 166 167 200 172 179, 180 144 204 161 162 184 168-170 189-191 182 176-178 164 165 186, 187 163 583 600 596, 597 599 59S 602-604 585 584 588 586 587 586 589 591 589 593. 594 74 74 73 74 71 73 72 ILLUSTRATIONS. XVll Z. Fire-places, Grates, and Stoves : — Arnott's open flre-place .... Amott's regulating: value for air to stoves Arnott'B stove . Aruott's ventilating valve Brick and tile stoves used in Germany, &c. Cast-iron common stove . Dunnacbie's fire-brick stove Galton grate, tbe Improved open fire- plaJce Kitcben close-range or kitchener Metal stove for solid fuel Napier's stove for solid fuel Spoor's American stove . Spoor's fire-bar of . Sylvester's sliding doors . Sylvester's stoves .... XL Furnaces and Cdpolab ; — Diagram of action of cupola tuyeres Diagram, of cupoTa with one row of tuyeres Diagram of heat distribution in blast furnaces Dufr^n^'s cupola and gas producer . Early Swedish gas blowpipe furnaces Gas annealing furnace Gas cupola .... Gas-fired brewer's copper Gas-fired metal heating mui!le . Godfrey and Hdwson's gas-puddliug furnace Gorman's furnace Greiner and Erpf's cupola Herbertz's cupola Ireland's cupola Krigar's cupola Modified Siemens' furnaces Outline dimensions of blast furnaces Ponsard's furnace and recuperator Iladcliffe's gas furnace Kiley's gas cupolas . Sections of blast furnaces Siemens' gas furnace Stewart's cupola Sudr^'s reverberatory furnaces Voisin's cupola Wilson's gas cupola . Woodwai'd's cupola .' XII. Gas-fired Boilers : — American trials of gas firing for boilers . Beaufum^'s gas-fired boiler Cornish boiler, with front for gas firing . Egg-ended boiler arranged for gas firing Fichet's gas-fired French boilers Gas-fired boiler at Glatigow .... Gas-fired boiler in ironworks .... Gas-fired boilers (Lancashire and Cornish) Gas-fired boilers with brick combustion chamber Hartman's plan for gas-fired boilers Haupt's arrangements for gas-fired boilers Lancashire boiler with gas-firiug front . Minary's plan for gas-fired boilers . Eegenerators for boiler firing by gas • 231 . 242 . 241 . 246 249 • 250 253. 254 ■ 233 225 • 232 247, 248 251, 252 243, 244 • 245 ;28, 229, 230 226, 227 • 535 • 541 S33 • 540 567-575 602 579 • 603 . 604 • 576. 577 • 594 543 538 • 534 • 539 • 586-593 53° ■ 595-597 599, 600. 601 . 580-583 531. 532 584. 585 • 536 559-562 • 542 ■ 578 ■ 537 423-435 391.392 436, 437 438-440 394-400 447-449 388, 389, 390 421, 422 441-446 401, 402 403-418 419, 420 • 393 • 605 XIII. Gab Producers ; — Beaufume's gas producer 1 4 r Benson's gas producer . . .... i^g Bischof's gas producer j . j Blast furnace tops for r,-a8te gases 133-140 Dowson's gas producer jg. jg- Ebelmen's gas pro.ducer ' j .2 Ekman's gas producer i,^, 144 Griibe and Liii-mann's producer ' jgg 395 406 406 408 410 411 412, 413 398 390 397 409 411 407 408 393. 394 392 643 648 641 647 671-674 691 677 691 692 675, 676 686 650 646 643 646 682-684 639 687 689, 690 677-679 640 679, 680 644 661 649 677 645 566-573 539, 540 573. 574 574-576 544-546 580-582 538, 539 562. 563 576-580 551 551-555 557 542 692 253 255 250 227- 232 266 251 252 268 XVlll ILLUSTRATIONS. XIII. Gas Producers — (continued) Healey's gas producer HowBon'B gas producer Kidd's gas producer Lowe's water gas producer Lundin's gas washing apparatus Minary'ii gas producers MUlIer and Flchet's gas producer Ponsard's superheated gazogene Siemens' circular gas producer Siemens' gas producer Strong's water gas producer Sutherland's gas producers Tervet's gas producer Tessi6 du Motay's producer Thwaite's gas producers . Wilson's automatic cleaning producer "Wilson's solid hearth producer Young and Beilby's gas producers . ^IV. Gas Stoves and Gas Fires : — Adams' gas cooking store Adams^ gas stove ..... Bond's (Dr.) euthermic gas stoves . Bunsen mixers for gas and air, sections of Curve of economy in burning gas, dia^am of Fletcher's ^as cooking stove . Fletclier's gas stove . Foulis's gas lire .... Gas lire, incandescent (Hislop's) Hislop's gas fire, brick burner for Main's gas cooking stove Keiiecting ga^ lire , Sehonheyder's gas stove . Siemens' coke and gas Sre Verity's gas lire Wright's gas cooking stove Wright's Imperial gas stove Wright's ceHector cooking stove XV. Heating Apparatus : — 262, 171 174 154. 155 156 147 149-153 17s 598 172. 173 146 IS7 167- 170 . 176 162, 163 177, 178 159-161 . 158 179. 180 274, 27s 256, 257 263, 264, 265, 265, 267 276, 277, 278, 279 • 255 271, 272 258, 259, 260 . 240 237 238 . 269 236 . 268 234. 235 239 . 270 261 • 273 Bissett's hot-air stove, diagram of . Cast-iron pipe hot-air stove Constantine's convoluted stove Curves of radiation from pipes, diagi'am of Hot-air stove, rectangular Hot-water circulating apparatus, diagram of Manchester Pantechnicon, sectional elevation The same, basement plan Mazas Prison heating arrangements Newcastle Infirmary heating and ventilating Perkins' hot-wattr heating system . Price's hot-water stove .... Ben^ Duvoir's hot-air stove Steam heating apparatus Talabot's hot-air stove XVI. Heating Gas Retorts: — . 297 . 280 290, 291, 292, 293, 294 • 329 288, 280 328 • 29s . 296 335. 336 ■ 337, 338 332, 333, 334 ■ 331 281, 282, 283, 284 • 330 285, 286, 287 Dessau or Didier genei-ator Heating retorts hy gas, Siemens' system . Hunt's modification of Kliinne's system Klonne's retort setting for gas-firing Liegel's arrangement for heating gas retorts Method of heating gas retorts Milller and Eichelbrenner's retort-heating gas furnace Schilling's system of heating retorts by gas Siemens' arrangement at Glasgow Gas Works Valon's retort-setting for gas firing Wilson's gas firing for single benches 487, 488 481, 482 497, 498 495. 496 489, 490 479, 480 483-486 493. 494 499i 500 491, 492 501. 502 PAGE 270 271 2S9 260 255 256. 257 272 688 270 254 261 268-270 273 265 274 264-265 264 276 429. 430 417 420, 421 433 416 427, 428 418,419 403 401 402 426 400 422 399 402 426 420 429 449 440 444-446 484 443 479 447 448 488, 489 491 486, 487 485 440,441 485 441,442 613 6io, 611 617 616 614 609, 610 611-613 615,6x6 617 614 618, 619 ILLUSTRATIONS. XIX XTII. Hot-blast Ovens or Stoves: — Baldwin's oval hot-blast ovens Baldwin's round ovens for hot blast Box-foot hot-blast ovens .... Concentric-pipe hot-blast stove Cowper's regenerative hot-blast stove Diagram of economy of coke with hot blast . " End-on " plan of increasing the size of ovens Forms of bricks for Cowper's stoves Horizontal-pipe hot-blast oven Later form of siphon-pipe oven Massicks & Orooke's hot-blast stove Neilson's arrangement at Clyde Iron Works in 1830 Neilson's arrangement in 1832 . Neilson's first hot-blast stove .... Neilson's hot-blast stoye with cast-iron vessels Pistol-pipe hot-blast oven Siphon-pipe hot-blast stove Whltwell's hot-blast store XVIII. Kilns and Ovens : — Baking oven for bread Bavarian malt kiln Calcining kiln for iron ore Coltness gas calcining kiln for ore . Copper ore roasting kiln Diagram of heat distribution in kilns Drying kiln for fuel Dunnachio's gas-fired brick kiln Ga£-fired malt kiln Gas-fired pottery mufBe . Guthrie's continuous kiln Guthrie's lime kiln . Hoffmann's brick kiln Limestone kiln Porcelain kiln . Small malt kiln Stoneware kiln XIX. Liquid Fdel Apparatus : — Archer's oil-gas apparatus Aydon's liquid fuel injectors Colonel Fooie's furnace for liquid fuel Fames' furnace for liquid fuel . Riley's furnace for liquid fuel Kussian liquid fuel injectors Wittenstrom's open trays for liquid fuel 318,319.320 3i5>3i6,3i7 305, 306 ■ 310.311 321 • 327 • 31.2 322, 323 307, 308 • 313 • 326 301,302 • 303, 304 298, 299 • 300 • 314 • 309 • 324, 325 S°9, 510 ■ 508 526, 527 • 13.S • 528 523 . 606 514-517 505, 506 518,519 ■ 522 525 520, 521 • 524 511,512 • 507 • 513 461, 462 460 457- 458 464 470 459 465, 466 457 459 469 4^4 455 453 453 460 458 466, 467 624 623 636, 637 228 637 633 694 627, 628 621, 622 628 632 636 629, 630 634 625, 626 622 626 ■ 185 186-192 • 183 . 184 . 216 193-209 305-313 XX. Mechanical Stokers : — Auld's mechanical stoker Bodmer's screw-grate Deacon's mechanical stoker Frisbie's grate and feeder Henderson's mechanical stoker Holroyd Smith's mechanical stoker McDougall's mechanical stoker Martin's furnace-doors Payen's fuel distributor Player's anthracite feeder Prideaux's automatic fire-doors Townsend's travelling prate Vicars' mechanical stoker 210-215 ■ 385. 386 359, 360 361, 362 • 370 374, 375, 376, 377, 378 • 371, 372, 373 • 379, 380 ■ 382, 383. 384 . 368, 369 356, 357. 358 ■ 387 . 365, 366, 367 • 363, 364 . 381 302 303 305 301 302 316 XXI. Miscellaneous : — Addie's ammonia recovery apparatus Coal workings, diagrams of Cubitt's chimney and enclosing tower . . . . Diagram of superficial areas of coal in various countries 181, 182 6, 7, 8, 9 224 5* 3i3--3tS 533, 534 517, 51S 524 527-529 525, 526 53° 532, 533 522 S16 534 521, 522 520 531 277 63,64 381 44 XX ILLUSTRATIONS. XXI. Miscellaneous — (continued) Faults in coal-beds .... French wood-drying chambers Geological section showing upright fossil tree Section of coal-basin, Somersetshire coal-field Spiral moTemeut of chimney gases, diagram of 4. ■? 42.43 504 620 I 40 2 41 223 380 PLATES, Microscopical structure of coal Bessemer's patent fuel .... Temperature charts of heating by gas stoves I, and II. III. IV.- VII. 36 224 422 CHEMICAL TECHNOLOGY. FUEL. THE BRANCHES OF MANXJFACTUEE CONNECTED WITH THE PKODUCTION OF FUEL AND THE PROCESS OF COMBUSTION. Every person who has directed his attention to the necessary conditions for carrjdng on any branch of manufacturing industry, will be well aware that heat and the effects produced by its agency, take precedence of all others. It is almost impossible to mention any manufacture in which either an elevated temperature or the power obtained by means of that temperature, is not em- ployed in some way or other. Even in agriculture, steam power is being gradually introduced for performing those operations in which manual labour has hitherto been employed ; small steam engines are now used on many farms of consequence in England and Scotland, the number of which will no doubt increase with a knowledge of scientific principles and with the necessity for saving labour in that all-important art, so that in a few years the application and utilization of artificial heat will probably be as much the rule in agiiculture as in the economical production of cotton fabrics, iron, or any of the chemical or metallurgical products of the world. Most of these manufactures, however, are entirely dependent on the agency of heat, and, generally speaking, of an intense heat, so that it is of importance to every one connected with the arts, to acquire a knowledge of the sources of heat, and the chemical and physical laws concerned in its production ; without this it is impossible to apply this invaluable agent in the manner best suited to the object in view and with the greatest amount of profit and economy. Every substance which is capable of burning in the air, that is, of com- bining with oxygen with the evolution of light and heat, might be employed as a heating agent, but of the numerous combustible substances which nature supplies, few are found in quantity sufficient to be generally applicable to the production of artificial heat. These few, however, are so abundant, and so generally diffused, that no inhabited country is entirely devoid of one or other of them ; indeed, so essential is artificial heat, in some form or other, to human existence, that no country totally without the means of producing it, would be habitable to any extent for any length of time. The wealth of this country, derived as it is chiefly from her success in manufactures, depends in a great measure on the abundant supply of one of iihe richest sources of artificial heat lying buried in the earth, in her coal- B 2 FUEL. fields. Great Britain had but small influence in the councils of Europe until these were discovered and turned to full account by the indomitable industry and enterprise of her inhabitants ; and without so invaluable an accessory to the acquirement of wealth and power, her commercial fate and fame might soon have sunk to a level with those of the most insignificant State in Europe. rtJEL. The substances to which allusion has been made above, and which we collectively call Fuel, are : wood ; peat or turf ; brown-coal or lignite ; pit-coal or coal ; wood-charcoal ; peat-charcoal ; coke from brown-coal and coal ; certain combustible gases ; cereals and refuse vegetable matter ; some liquid hydro- carbons ; and artificial fuel. All these substances are more or less closely allied to wood or woody fibre, from which they seem to have originally been mainly derived, and all are indebted for their combustible properties to the carbon and hydrogen of which they are essentially composed. These two elements, together with oxygen and small quantities of nitro- gen, sulphur, phosphorus, water, and inorganic salts (ash), compose the entire mass of the natural fuels ; their relative value as fuel depending in a great measure on the proportions in which the two former elements enter into their composition. Most artificial fuels contain carbon as the essential ingredient ; the other constituents, with the exception of the ash, having been expelled in the pro- cesses of manufacture. The value of fuel is diminished by the ash, which is not combustible ; and the sulphur and phosphorus sometimes present are peculiarly prejudicial in some of its applications. The facility with which fuel is ignited and continues to burn, depends to a great extent on its chemical constitution and on the porosity of its texture. A large amount of hydrogen is generally favourable to rapid ignition ; this element, in combination with a portion of the carbon, separates, as carburetted hydrogen, at a temperature below redness, and the combustible gas thus produced burns and heats the remainder of the fuel, causing the combustion to spread. The portion of carbon which is not burnt in the form of gaseous hydrocarbons, is left by the escape of the gas in such a porous state, that the atmospheric oxygen easily obtains access, and the whole is consumed. The property of burning with flame is thus intimately connected with the presence of hydrogen in the combustible, and the artificial fuels which contain no hydrogen, only produce flame when the quantity of air directly supplied to them is insufficient for the production of carbonic acid, or when the carbonic acid formed passes through a layer of .glowing carbon ; carbonic oxide is then produced, which may again be ignited in contact with more air. Steam may be used instead of air, or a mixture of steam .and air may be employed in the production of carbonic oxide mixed with hydrogen. Wood, peat, and some kinds of brown and gas coals produce the longest flame ; they contain the largest amount of hydrogen, and are most easily decomposed. Coal generally is not so inflammable, and some varieties, as anthracite, burn without flame, like charcoal and the other artificial fuels. These distinctions are important in many applications of fuel. Where the materials to be heated are separated from the combustible, an inflammable fuel must be selected, the greatest heat being then found at the extremity of the flame. On the other hand, great local intensity of heat is obtained, so to speak, in immediate contact with those kinds of fuel which are consumed withcmt flame. ■WOOD. The trunk, roots, and larger branches of trees are all called wood. The other parts, leaves, twigs, and small branches, called brushwood, are likewise WATEE CONTAINED IN WOOD. used as fuel, and differ from the more solid portions in the proportions of the several constituents to be mentioned hereafter, and in the inflammability and heating power which they exhibit ; but as these form a very small proportion of the wood employed as fuel, it is unnecessary to specify these differences more minutely than is done in the subsequent tables, showing the elementary composition and amount of ash in some of the more important. Wood is composed of three different substances : first, woody fibre, C^^fi^, which forms the cells and vessels of the plant, and makes up the chief part of its bulk ; second, the constituents of the sap contained in the vessels ; and last, water. The most important of the sap constituents is a soluble gum (lignin), amounting on the average to 13 per cent, of the wood, and having the same elementary composition as cellulose itself. Recently felled wood necessarily contains all three constituents. The two first are combustible, and produce heat ; the water, on the contrary, whilst the wood is burning, is converted into vapour at the expense of a portion of this heat. As woody fibre and water are common to all kinds of wood, the difference which has been shown to exist between different woods must depend entirely on the constituents of their sap, and on their structure (density). Notwithstanding the great difference, chemically speaking, in the constituents of the sap (the coniferous woods containing resinous matter ; the beech and birch, extrac- tive ; and the oak, tannin), the accurate analysis of dried woods has shown that they contain the three elementary constituents, carbon, hydrogen, and oxygen, nearly in the same proportions as pure woody fibre does. The constituents of the sap, therefore, can form but a very small proportion of the whole bulk of the wood, or else they have the same composition ; and their action cannot materially alter the value of the wood as fuel, although it becomes very perceptible when the wood is applied to certain practical purposes, as in the process of tanning. The amount of water in wood has greater influence, and is of much more importance, as it materially influences its calorific power. Water is generally most abundant in wood at the time of the flow of the sap, and least, when the growth is less rapid ; for which reason, wood should always be felled at the latter stage, unless the important secondary uses for which it is sometimes cultivated, as the tannin in the bark, &c., render it desirable to fell it at an earlier stage of growth. The amount of water (sap) in wood differs according to the time of year at which it is felled. Thus, Schlibler and Neuffer found : — Water per cent. Woods. At the end of January, Ash . . . 28.8 Svcamore . . 33.6 Horse-chestnut . 40.2 White Fir . - 52.7 At the beginning of April. 38.6 40-3 47-1 61.0 It is also greater in the young shoots and twigs than in the more solid stem, and varies also in amount in woods of a like nature but of different botanical species, as the following table (given also by Schiibler and Neuffer) shows : — 100 Parts of fresh cut Wood from the Water, Hornbeam [Carpinus hetulus) contain AViUow (Salix caprea) Svcamore {Acer pseitdoplatarms) Mountain Ash (Sorhvs aucupana) Ash {^Fraxinus excelsior) . Birch (Betida alba) . Wild service tree {Crataegus tormin Oak ( Quercus robur) Pedicle Oak ( Quercus pedunculata) White Fir (Fvvus abies, Dur. ) . Horse-chestnut {Aesculus hippocast.) 18.6 26.0 27.0 28.3 28.7 30.8 32-3 34-7 35-4 37-1 38.2 Pine (Pinus sylvestris L.) contai Red Beech (Fagus sylvatica) Alder {Betnla alnus) Aspen (Populns tremula) . Elm ( Vlmus campestris) . Red Fir {Pinus picea, Dur.) Ijme Tree {Tiha europ(ea) Italian Poplar (Populus italica) Larch [Pinus larix) . White Poplar (Populus alba) Black Poplar {Populus nigra) Water. 39-7 397 41.6 437 44-5 45.2 47.1 48.2 48.6 50.6 518 4 WATKK CONTAINED IN WOOD. Chevandier examined the hygroscopic state of the wood of the beech, oak, white beech, birch, aspen, alder, willow, fir, and pine, from ditferent parts of the same tree and at intervals of six months, one year, one and a half, and two years, after the trees had been felled. The numerous specimens upon which he experimented, amounting to i8i in number, wei-e taken from trees of various ages, grown upon different soils, and the specimens were exposed to the free access of air in an open shed, protected, however, from the rain and the direct action of the sun's rays. The amount of moisture in each was determined at the different intervals by drying weighed quantities, in the form of sawdust, at a temperature of 140° C. (284° F.) in a vacuum, until they ceased to lose weight. From these experiments, it appeared that the soil and site upon which the trees grew had no appreciable influence on the amount of moisture con- tained in or retained by the wood. The minimum of hygrometric water in the woods, or the maximum state of dryness, was attained for the greater number after the lapse of a year and a half ; the others required two years to be brought to the same state. The resinous woods dry more rapidly, but likewise absorb moisture with greater avidity, than those which contain no resin ; and among the latter, the softer kinds (birch, aspen, alder, willow) contain more water in the fresh state than the harder woods ; they lose this water, however, with greater ease, and can be more thoroughly dried. The following are the mean of the results obtained in the experiments : — I. Mean quantity of Hygrometric Water contained in the Eesinous Woods. Trunk- wood . . half a year after felling . . . 29 per cent. 32 38 Brushwood Young branch-wood . „ „ „ Trunk- wool . in the driest state Brushwood Young branch-wooJ IS IS IS 2. Mean quantity of Hygrometric Water contained in the Non-Eesinous Woods. half a year after felling . Trunk-wood Brushwood Young branch-wood Trunk-wood Brushwood Young branoh-wooJ in the driest state 26 per cent • 34 36 17 20 19 These numbers must be considered as minima, single specimens being more perfectly dried than wood stacked and not freely exposed to the air. In recently felled wood, therefore, from 3^ to ■!• of its weight is water, and in that commonly used for fuel about |. This quantity is very much diminished by keeping the wood dry and exposed to the air, but it is not entirely removed under any circumstances. After the expiration of one and a half or two years, when the wood is in the driest state to which it can be brought by exposure, the hygroscopic properties of the air and the wood appear to be in a state of equilibrium and to balance each other, the amount of water in the latter varying within narrow limits with the season of the year and with the hygrometric state of the atmosphere at the time of obser- vation. In this state of dryness, in which wood is best adapted for use as fuel, the wood is said to be air dried. The remaining moisture can only be expelled with the aid of heat, and the last portions with such difliculty that the wood commences at the same time to decompose, and becomes brown. WATER CONTAINED IN WOOD. Violette heated wood, which had been seasoned for two years, for two hours in a current of super-heated steam, at i25°-225°C. (2S7°-437° F.). The loss of water is given below : — Temp. C. Water expelled from 100 part 8 of Terap. P. Oak. Ash. Elm. Walnut. 15-55 125° 15.26 14.78 «5-32 257° '5°! 1793 -16.19 17.02 17-43 302° 175 3213 21.22 — 21.00 347° 200° 35.80 27-51 33-38 — 392° 225° 44-31 33-38 40.56 36.56 437° Between 200° C. (392° F.) and 225° C. (437° F.) there was slight car- bonization, and water alone was not given off. Rumford heated the following air-dried woods at a temperature of 136° C. (277° F.) as long as they lost weight without being chemically changed, and found that 100 parts of Oak-wood lost . . 16.64 Fir-wood lost . • 17-53 Elm . 18.20 Birch „ • 19-38 Beech „ . 18.56 Lime „ - '8.79 Maple ,, . 18.63 Poplar „ • 19-SS* For practical purposes, such a complete state of dryness can seldom be attained, and the wood used for fuel, after exposure to the air for ten or twelve months, contains from 20 to 25 per cent, of water. The former number taken as the mean, reduces 100 lbs. of air-dried wood to only 80 lbs. of real fuel. Wood, several years old, which had been kept in a warm room for six months, still retained about 17 per cent, of water { Winkler), t The following table, from Wagner's Technology, gives the average time in which woods used for fuel are fit for felling : — Wood. Years. Wood. Years. Oak . . 50 — 60 Birch . 20—25 Bed Beech . 80—120 White Fir . 50—60 White Beech . no— 120 Bed Fir 70—80 Elm . . 20—30 ( 'ommon Fir . 80 — 100 Ash . . 20 — 30 Larch 50 — 60 Alder . . 20—30 Wood is commonly divided into the hard and soft kinds, a distinction grounded on the facility with which it is worked, and on its power of pro- ducing heat. The former class, embracing the wood of the oak, white and red beech, birch, elm, and alder, contains in an equal bulk more solid fibre, and the vessels are narrower and more closely packed than in that of the softer kind, which includes the wood of the pine, fir, white fir, larch, lime, willow, and poplar. High situations, much exposed to wind, and a poor soil, cause the annual rings to be less developed, and consequently more closely packed, than is the case with wood which is protected and grows on the more fruitful soil of valleys. The specific gravity of wood must neces- sarily stand in a certain relation to its hardne.ss, and increase with the latter, and this being a point of some practical importance, several experimenters * The same kinds of wood, freed in like manner from water at a temperature of 136° 0. (■277"' F.) and exposed in shavings to the air, absorbed in winter (at 45° F.) from 171019 per cent, and in summer {at 62° F.) from 6 to 9 per cent, of water within 24 hours, which facts easily explain why wood is dried with so much difRculty. f The wood composing: the beam of a room 150 years old and preserved from moistm-e, had a sp. gr. of 0.682 and contained 10.5 per cent, water. 6 SPECIFIC GRAVITY OF WOOD. have turned their attention to the subject. The specific gravity of wood, , which is the sum of the weight of the soUd matter with that of the water contained in it, and of the air of the pores,* cannot be ascertained with that degree of accuracy to which we are accustomed in scientific investigations, as these different constituents occur in variable proportions. The difficulty of arriving at a knowledge of the true specific gravity of wood has been very much increased by the different, and often inaccurate, modes of experimenting which have been adopted for determining this point. Wood, supposing it free from pores containing air, is sensibly heavier than water. Thus, after destro3ring the pores by rasping and determining the volume of the raspings, the specific gravity of lime-wood was found to be 1. 1 3, of fir- wood 1. 1 6, of oak-wood 1.27, of beiech-wood 1.29. Rumford's experiments led to .the conclusion that the solid part of all woods without dis- tinction had a specific gravity of about 1.5, and experience has shown that wood sinks after long immersion in water, when the air' has been expelled from it. The specific gravity of wood has been observed to vary in the same variety with the age of the specimen, the nature of the soil upon which it has been grown, the climate, &c. ; it is not even the same in different parts of the same tree. Young wood is specifically heavier than old, and heart-wood bears a like relation to sap-wood. In the following table, the respective weights of the different kinds of wood, in the state in which they are tised as fuel, are given according to the best authorities. SPECIFIC GRAVITY OF DIFFERENT KINDS OF WOOD; WATER BEING UNITY. I. ir. III. IV. v. Variety of Wood. Recently Dried in Strongly Strongly felled. air. 0.7075 dried. dried. Common Oak (Quercus robur) Pedicle Oak (Quercim pedunmlata) I.07S4 0.6441 0.663 0.929 1.0494 0.6777 — 0.663 — White Willow {Salix alba) . . . 0.9859 0.4873 0.4464 0.457 0.585 Beech (Fagvs sylvatica) , , 0.9822 0.5907 0.5422 0.560 0.852 Elm ( Ulmms campestris) . 0.9476 0.5474 0.5788 0.518 0.600 Hornbeam {Carpinus betv,lu.i) 0.9452 0.7695 0.691 — Larch {Pinus larix) 0.920S 0-473S — 0.441 — Scotch Fir (Pinm sylvestr.is) . 0.9121 0.5502 0.4205 0.48s — Sycamore {Acer pseudoplatanus) . 0.9036 0.6592 05779 0.618 0-755 Ash (Fraxinus excelsior) 0.9036 0.6440 0.6137 0.619 0.734 Eirch (Bettda alba) 0.9012 0.6274 0.5699 0.598 Mountain Ash {Sorhus aucuparia) 0.8993 0.6440 0-552 Fir (Pinm abies, Duroi) 0.8941 0-S550 0.4303 0.493 0.550 Silver Fir {Pinus picea, Dur. ) 0.8699 0.4716 0.3838 0.434 Wild service {Cratcegus torminalis) 0.8633 0.5910 0.549 0.874 Horse-chestnut [Aesculus hippoc.) . Alder (Betvla alnus) 0.8614 0-S749 0.8571 0.5001 0.443 0.800 Lime {Tilia europcea) 0.8170 0.4390 0.3480 0.431 0.604 Black Poplar {Populus nigra) 0.7795 0.3656 0.346 0-383 Aspen (Populus tremula) Italian Poplar [Populus italica) Ground Willow {SaHx caprea) 0.7654 0.7634 071SS 0.4302 10-3931 0.5289 0.4402 0.418 0.501 Guaificnm Wnnd .... Grif- 1-3420 Ebony . , fith 1.2260 — — — * Thus Eumford calculated from the sp. gr. of the fresh wood of sappy trees, and from that of its solid parts, that i cub. ft. of fresh oak-wood contained 390 cub. in. of solid fibre, 360 cub. in. of sap, and 240 cub. in. of enclosed air. Poplar- wood in 'the same state contains in the cubic foot, 243 cub. in. of fibre, 219 cub. in. of sap, and 538 cub. in. of air ; lime- wood, 265 cub. in. of wood, 365 cub. in. of sap, and 370 cub. in. of air. According to another calculation, i cub. ft. of air-dried lime-wood contains 558 cub. in. of air in the pores ; fir-wood 586 cub.'in. • oak- wood, 481 cuh, in. ; and b^ech-wood, 457 ub. in. > • ■ 1 SPECIFIC GRAVITY OP WOOD. 7 The columns I. and II. contain the weights ascertained by Hartig ; and column III. the less accurate determination of Wernek. The specimens of wood employed by the latter were dried in an oven, until they ceased to lose weight, and the loss which they sustained, on being immersed in water, was then determined. In column IV., the results obtained by Winkler are given, who weighed an exact cubic inch of each wood. The specimens had been kept for six months in a strongly heated chamber, and the water they contained had been thus reduced to an average of about 9 per cent. Column V. contains Mushenbroek's numbers. A very extensive list of the relative weights of the woods from different countries will be found in the Reports of the Juries of the Exhibition of 1851. The following determinations of the specific gravity of woods were made by Karmarsh. Names of Woods. Maple . Apple . Birch . Pear . Ked Beech Box . Cedar . Ebony . Oak . Alder . Ash . Pine . Scotch Fir Larch . Lime . Poplar . Guaiac Silver Fir Elm . WilloHT White Beeth aPSCIFlC GBATITT. In the green state. Limits. 0. 843 — 0. 944 0.960 — 1. 137 0.851-0.987 0.852 — 1. 169 0.885—1.052 0.973 0.809—0.994 0.901 0.778—0.927 0.852 0.848—0.993 0920 0.811— I COS 0.908 0.694—0.924 0.809 0.710—0.878 0.794 0.758—0.956 0.857 „°<;^94 0.894 0.878—0.941 0.909 0.838-0.855 0.846 0.939 -1. 137 1.038 Mean. 0.893 1.048 0.919 0.980 In the air-dried state Limits. 0.645 — 0.750 0.734-0793 0.688—0.738 0.646 — 0.732 0.690— O.S52 0.912 — 1.031 0.561-0.575 1.187—1.331 0.650 — 0.920 o 505—0.680 0.540—0.845 0.454 — 0481 °-565 °S59— 0.604 0.383—0.591 1.263— 1.342 0.498 — 0.746 0.568 — 0.671 0.392—0.530 0.728—0.790 Mean. 0.697 0.763 0713 0.689 0.771 ,0.971 0.568 1.259 0.78s 0.592 0.692 0467 0.565 0.581 0.487 1.302 0.622 0.619 0.461 0.759 Mean weight of I cub. foot of air-dried Wood in lbs.« 37 lbs. 4t 38 37- 41 52 30 67 42 31 37 25 30 31 26 69 33 3.; 25 40 Most trustworthy results, obtained by the method of immersion, have been recorded by Marcus Bull, who took the precaution of covering each specimen with a varnish of sp. gr. = 1.000, which, without giving rise to eiTor, ensured the presence of the whole natural quantity of air in the wood. The most important of his experiments are given in the table below ; they apply only to foreign woods. j rr j j Walnut (with scaly bark) White Oak (chestnut ?) . American Ash Beech Hornbeam ..... 0.720 Wild Apple 0.697 ''""■"'' 0.618 1. 000 0.885 0.772 0.724 Virginian Cherry . American Elm Virginian Cedar Yellow Pine . Birch (poplar-IeavbJ) American Horse-cheblmit Italian Poplar 0.597 0.580 0.565 0-551 0.530 0.522 0-397 The European woods, as shown in the first table above, are therefore rather less than one-half lighter than water, and a cubic foot weighs from 26 to 42 lbs. Wood dried m the air decreases in bulk, often as much as o i of the whole. * The Hanoverian pound is equal to 1.031114 lb. English. 8 ASH OF WOOD. A numerous series of experiments by Marcus Bull have proved that in an ordinary stack or pile of American wood, there is contained, for every 56 parts of actual wood, 44 parts of unoccupied space. This fact, in conjunction with the experiments on the specific gravity of different woods given in the table at page 7, led to the following actual quantity of wood in either given compass : — Founds avoirdupois in a cubic meter. (3S.3 cubic feet English.) Pounds avoirdupois in a cubic foot. Walnut (with scaly bark) White Oak (chestnut?) . American Ash Beech .... Hornbeam American Elm Yellow Pine . Birch (poplar-leaved) American Horse-chestnut Italian Poplar 1227.6 1075.8 919.4 880.0 875-6 704.0 668.0 647.6 6336 481.8 34.7 30.5 26.0 24.9 24.8 19.9 18.9 18.3 17.9 13.6 As wood that has been 12 months felled still contains about 25 per cent, of water, the foregoing numbers must be multiplied by f in order to yield the actual amount of dry wood. In mountainous districts, where the wooded parts are steep and in- tersected with rapid streams, the latter are frequently made subservient in transporting wood for fuel. In the Black Forest, in the neighbourhood of Salzburg, and in other places, large quantities of wood are floated down the rivers in this manner ; but when this practice is more carefully looked into, it appears that the advantage of cheap transport is partly counterbalanced by the inferior quality of the wood so transported. Long immersion in water necessarily dissolves out all the soluble matters, and thus diminishes the volume of the wood, as well as its power of producing heat. Wernek asserts that I cubic foot of wood may lose i lb. of its weight by being floated. When wood is burnt, it always leaves an incombustible residue, or ash ; this residue consists of earthy and alkaline salts, which the living plant takes up from the soil, and which are essential to its healthy development. This ash consists of lime, potash, soda, oxide of iron, oxide of manganese, and silica, in combination with carbonic acid, chlorine, sulphur, sulphuric acid, and phosphoric acid. Many of the bases in the sap are in combination with organic acids, and these salts become carbonates on incineration. The greater part of the ash, indeed, is composed of the carbonates of lime and of the alkalies. The silica appeal's to exist in an uncombined state in the juices of the plant and the sulphur and phosphorus must be traced to the albu- minous constituents of the latter. The amount of ash varies with the kind of wood, and is likewise different in the several parts of the same tree and in trees of different age. The soil upon which the trees are grown has also some influence on the quantity and nature of the ash. In some varieties of wood, the ash does not exceed ^ per cent., whilst others contain from 2 to 5 per cent. The following results were obtained by Berthier and Karsten from the in- cineration of several varieties of wood : — COMPOSITION OF WOOD ASHES. Amount of Ash in lOO parts : — II. Varieties of Wood. BKRTHIEB. EABSTEN. In younf? wood. In old wood. Silver Fir (PintiS^icco) . 0.83 o.is O.IS Birch 1. 00 0.25 0.30 Scotch Fir (Pinus sylvestris) 1.24 0.12 0.1S Oak . . 2.50 0.15 0.1 1 Lime 5.00 0.40 — Fir (Pinv^ abies) 0,23 0,2s White Beech . 1 0.32 0.35 Alder 035 0.40 Red Beech .... 1 0.38 0.40 Berthier's results were obtained with air-dried wood. More recent researches on this subject are those of Chevandier, and the following are the mean quantities of 524 determinations of ash which he has made : — Wood. No. of Determinations. Mean Percentage of Ash. Willow .... 17 2.00 Aspen Oak 59 1-73 93 1.65 Hornbeam 73 1.62 Alder . 26 1.38 Beech . 93 1.06 Scotch Fir 28 1.04 Silver Fir 46 1.02 Birch .... 89 0.85 Portion of the Tree. Percentage of Ash. Young shoots, entire Wood split into billets llranches, entire wood Faggots of twigs . . ... 1.23 1-34 1-54 2.27 COMPOSITION OF CERTAIN WOOD ASHES. Constituents per cent. Pagus Sylvatica. Finns Sylvestris. Larix EuropKa. Potash Soda ........ Lime Magnesia . Manganic Oxide (MujO,) Ferr.c Phosphate {2¥e^O^,3Pfi^ Tricalcic Phosphate .... Calcic Sulphate Sodic Chloride Silica Total .... Percentage of Ash in the Wood at 100° C. (212° F.) 15.80 2.76 60.35 11.28 1.84 3-99 2.30 0.21 1.46 2.79 15.99 30.36 19.76 18.17 5.10 3.31 ..48 3-04 15.24 7.27 25.85 24.50 13.51 6.18 2.91 0.92 3.60 99-99 100.00 6.143 99.98 0.322 These analyses are due to Bottiager. 10 ELEMENTARY COMPOSITION OF WOOD. Further particulars as to the composition of wood-ash will be found in the Annalen der Chemie und Pharmacie for 1843, 1844, 1845. It has already been stated that the constituents of wood, as regards the relative proportions of their elements, do not differ much from pure woody fibre (wood purified from extractive matter and water). The knowledge of these proportions not only serves to explain the peculiar properties of the several woods, but is essential in estimating their relative values. Schbdler and Petersen have furnished us with the following results derived from the elementary analysis of woods dried at 100° C. (212° F.) and previously pulverized : In ICO parts they found the following relations : — Species of Wood. Carbon. Hydro- gen. Oxygen. Species of Wood. Carbon. Hydro- gen. Oxygen. Pure woody fibre . QuercuB robur Fraxinus excelsior Acer campeBtris . Fagus sylvatica . Eetula alba Ulmns carapestris 52-65 49-43 49-36 49.80 48.60 50-19 5-25 6.07 6.07s 6.31 6.30 6-375 6.425 42.10 44.50 44-57 43-89 45-17 45.02 43-39 Populns nigra Tilia europ«a Salix fragilis Pinus abies Pinus picea Pinus sylvestria Pinus larix . 49.70 49.41 48.44 49-95 49-59 49-94 50.11 6.31 6.86 6.36 6.41 6.38 6.25 6.31 43-99 43-73 44.80 43-65 44.02 43.81 43-58 The following determinations of the elementary composition of some European woods have been lately made with great care by Chevandier.* The specimens were dried at 140° C. (284° F.). ELEMENTARY COMPOSITION OF SOLID WOOD, AFTER DEDUCTING THE ASH. Carbon. Hydrogen. • Oiygcn. Nitrogen. Beech Oak . Birch Aspen Willow . 49.89 50.64 50.61 50-31 51-75 6.07 6.03 6.23 6.32 6.19 43-11 42.05 42.04 42.39 41.08 0.93 mean of 7 analyses 1.28 ,, 5 1. 12 ,, 4 0.98 „ 3 0.98 „ 2 ELEMBN-TAEY COMPOSITION OF BRUSHWOOD AND BRANCHES, AFTER DEDUCTING THE ASH. Carbon. Hydrogen. Oiygen. Nitrogen. Beech Oak . Birch Aspen Willow . ■ 51.08 50.89 51-93 ;i.02 54-03 6.23 6.16 6.31 6.28 6.56 41.61 41.94 40.69 41.65 37-93 1 .08 mean of 4 analyses I-OI „ 4 1-07 „ 3 i-OS „ 2 1.48 ,. 2 Although hydrogen and oxygen are contained in woody fibre in the same proportions as those in which they unite to form water (i : 8), this relative proportion is not accurately observed in the different woods, the hydrogen being often contained in them in larger and in variable quantity. The composition of different woods does not vary, however, so much as might be anticipated, • "Ann. Chim. Phys." [3], 10, igg. PEAT. 1 1 As a general result, ordinary air-dried wood may be considered as being composed of : 20 per cent, hygroscopic watei', 40 „ oxygen and hydrogen in the proportions in which they unite to form water, 40 „ charcoal, including I per cent, of ash. Heated from 120° to 140° C. (248° — 284° F.) the wood loses its hygro- scopic water and becomes hiln-dried, and then contains : 50 per cent, of oxygen and hydrogen in the proportions in which they combine to foi-m water, 50 „ charcoal, containing i per cent, of ash. The wood is chemically changed when heated more strongly, as will be described under the head of charcoal. TXJBP OB PEAT. When a district is spread out in the form of a flat basin of greater or smaller dimensions, and the water which collects upon its surface or rises from springs, cannot freely escape, but stagnates for a length of time, a shallow lake is formed, as is not uncommon in the temperate zones, particu- larly where evaporation goes on slowly and the atmosphere is habitually moist, as, for instance, in Ireland. Under these conditions, water-plants of all kinds, sedges, rushes, reeds, algse, mosses, more especially Sphagnum, even shrubby plants, as willows, &c., spread from the sides towai'ds the centre of the pool, and quickly form a thick covering of vegetation. With the change of season, these plants die and fall to the ground, making room for a second crop in the following spring ; this process goes on from year to year, until the shallow pool becomes a bog, and is at length completely filled up with a loose spongy vegetable mass. The remains of the plants immersed in water quickly decay ; they lose their original solidity with the simultaneous evolution of gas (marsh gas and carbonic acid), and a disagreeable and noxious smell is produced ; at the same time oxygen is absorbed from the atmosphere and from compounds, such as sulphates, contained in the soil and the water surrounding them, the sulphates being reduced to sulphides. The vegetable matters become brown and soft, and are eventually converted into a black-coloured, soap-like mass. The debris of plants reduced to this state by decay, or in which the process is still going on, is called turf or peat. Such is now almost universally acknowledged to be the natural process by which peat has been produced, and the older hypotheses, that it is a forma- tion as old as the hills and valleys where it occurs ; a bituminous deposit from the sea ; the wreck of once floating islands ; or an actually growing vegetable substance, may be viewed as entirely exploded. The plants from which turf seems to have been principally formed in the northern hemisphere are the mosses, amongst which Sphagnum palustre predominates. Besides these, heath and fern, rushes and reeds are frequent, and one or more species of cotton-grass {Eriophorum) are also common. Whole trees, oaks, firs, ash, birch, yew, and willow, have been frequently found at the bottom of peat-bogs, sometimes erect, as if they had been gradually buried by the encroaching growths of moss, in which they have ultimately perished, at others lying prostrate, in which position they may have aided in impeding the flow of water and in accelerating the growth of the bog. Human remains have been dug up in turf-bogs, some- times in a state of high preservation, although the hair clothes and antique sandals afford evidence of a very long submersion ; thus testifying to the powerful preservative or antiseptic qualities of the turf. Remains of animals now ey-tinot, and fatty substances known as bog-butter, and 12 PEAT. consisting principally, according to Brazier, of an acid which he calls hutyro-limnodic acid (CjjHjjOj),* support the foregoing statements. In the southern hemisphere, according to Darwin, peat doe.s not occur nearer the equator than the 4Sth degree of latitude, and the peat there formed is composed of the remains of almost all the plants growing in the vicinity, including the grasses ; it is remarkable, however, that no mosses appear to have taken part in the formation of South American peat, which is chiefly composed of the remains of a plant called by Brown Astelia ptimilri. Small deposits of turf are found in almost every country, but districts of immense extent occur upon the low shores of the North Sea and German Ocean (Holland and North Germany), in the formation of some of which the waters of the sea appear to have borne a part. In mountainous districts, the hollows are frequently filled with peat-bogs, the constant assemblage of clouds upon the mountains favouring their growth by a gradual but incessant supply of moisture. These bogs, how- ever, are seldom very extensive, nor does the deposit generally exceed 6 feet in thickness. In Holland entire districts are covered by this formation ; in Britain the area of peat has been estimated by Hans Danchell at 6,000,000 acres, each acre being, in his opinion, capable of yielding 1000 tons of peat charcoal ; whilst in Ireland one-seventh of the whole island, or an area of 2,830,000 acres, consists of peat-moor. In France, the great marsh of Montoire, near the mouth of the Loire, is said by Blavier to be more than 50 leagues in circumference. These vast growths of peat are deep in proportion to their extent, the moors of Holland averaging 2 fathoms, while those of Ireland are often 30 feet in depth. Sometimes the peat formation appears to have taken place at successive periods ; the layers are then generally separated by deposits of sand. Although peat sometimes comes quite to the surface, it is frequently covered with sand or mould, but is always found in horizontal layers of moderate thickness. Peat belongs to the more extensively diffused kinds of fossil fuel, and two kinds may be distinguished, diflfering in geological age, and in the amount of decomposition to which they have been subject. They are : 1. Recent peat, in which the structure of the roots and stems of the plants is still perfect ; it is soft and exceedingly fragile, and of a very porous, specifically light texture. Passing from a light to a blackish-brown colour, and containing the roots and fibres which are really foreign to it dis- seminated through an earthy matrix, it gradually verges, without any marked distinction, into the 2. Older peat, in which all organic structure has disappeared, and the fibrous has given place to an earthy texture. Those kinds of peat are con- sidered the oldest in which the structure has become so fine in the gmin, so free from fibre, and so dense as to appear, when freshly cut, as smooth and shining as wax or pitch. All varieties of peat belonging to this class are distinctly heavier than those belonging to the former ; whilst a cubic foot of the more porous kind only weighs about 4 lbs., the weight of a cubic foot of the old peat amounts to from 12 to 20 times as much (Karmarsh).t • "Chem. Gaz." Oct. i, 1852. Macadam has shown quite recently, however, that this fatty substance really has the composition of butter, and appears to be identical with it : " Joum. Ohem. Soc. Abstr." 1887, p. 17, and " Min. Mag." 6, 175. t The gi-and- duchy of Hesse comprises extensive peat-moors. The Ehine, formerly ob- stru.-ted in its course at Bingen, was forced to spend its waters over the low-lands opposite Mayence, and the stagnating water which remained after the Ehine had forced its passage through the rocks at Bingen gave rise, in the still swampy district called Ried, to the formation of peat, which is now cut at Pfilngstadt and Griesheim. The peat of the latter locality is dense, heavy, and black, and closely related to the older peat ; that of the former is light, with- out earthy constituents, rich in the roots of plants, of a light colour, and evidently belongs to the more recent species. The quality of the Griesheim peat is very superior to that from the other locality. CUrriNG TVRV OR PEAT. 1 3 The humic acid contained in peat, and observed by Sprengel, as also the various other products of the decomposition of woody fibre, which consti- tute its chief mass, are of little interest as regards its application. The same may be said of the resins discovered in it by Mulder, and described by him. Peat is cut and prepared for use in a very simple manner. In Ireland, Germany, and most other parts, the surface of the deposit is laid bare by re- moving the sod or earth above it, and the peat is cut into the shape of thick bricks with common spades, or with the slade, an instrument resembling a long spade with a portion of the blade turned up at right angles on the one side ; the peats are then placed to dry, piled up loosely one against the other, or upon some kind of support. Car^ is taken to separate the peat of the upper part of the layer, which is young and fibrous, from the heavy and more plentiful lower peat. The process adopted in Holland is somewhat more circuitous, but certainly more appropriate, exactly resembling the preparation of bricks by moulding. The peat is scooped with spades as long as practicable, and when the peaty mass, which is more spongy than solid, becomes too thin to be thus ad- vantageously collected, a particular kind of instrument is substituted for the scoop commonly used upon such occasions. This consists of a kind of sharpened iron cylinder fixed to a handle forming, as it were, the side of the scoop ; the cylinder is perforated with small holes on every side, and serves as a support for the bottom, which is formed of a net or piece of cloth. This instrument prevents any quantity of water being scooped up with the peat, the holes allowing the water to run off immediately. The peat-mud collected in this manner is converted into a homogeneous mass by treading with the feet and stirring about with rakes like mortar ; the stones are picked out, and it is then spread out evenly in layers of one foot in thickness in large wooden boxes, such as are used for slaking lime, in order that the water may run off and the mass become dry. To facilitate this, and prevent the adhesion of earthy matter, the bottom of the box is previously covered with hay. After some days, when the mass exhibits a certain consistence, it is subjected to another operation, in which women and children are employed, who, instead of beating it, strap flat boards, like snow-shoes, to their feet, and stamp upon it in all directions. The treading is continued until no im- pression is produced by a common footstep : and the peat is lastly struck with beaters until the surface i.s uniform. The whole cake, eight or nine inches in thickness, is divided by means of long laths into squares of about four inches across. The thickness of the cake corre.sponds with the length of the bricks. To effect the complete desiccation, the first brick taken out is laid transversely upon the second, the third is laid upon the foui-th, and so on ; this order is afterwards reversed when the pieces are piled. In some places, the peat-mud is scooped out with buckets on to a dry place, and the water being allowed to drain away, it is made into bricks with moulds. Too much water in the peat may completely destroy its value and render it incapable of being piled. The value of peat is in proportion to its dryness, density, and firmness. If it possesses these qualities in a slight degree only, it suffers by carriage and by keeping, the upper layers of the heap compressing and breaking the lower layers, which are thus rendered valueless. The porosity and brittleness of peat prevent its application in all cases where the fuel and other matters to be heated are piled up to any considerable height one upon the other. Dense peat comprises, in an equal bulk, much more combustible matter than porous peat. This fact has led, in recent times, particularly in Ireland, to the construction of presses for the purpose of improving the quality of the lighter kinds of peat, but the difiiculty of introducing a machine which is at once rapid in its action, cheap, and effective, has not yet been entirely over- 14 WATER IN PEAT. come, the elasticity of the fibre offering great obstacles to the action of the press. It is evident that the use of a press, in addition to the advantages named, would also very much aid the drying process. In one experiment, a brick weighing 8 lbs. lost 2.5 lbs. of water under the press. Where a large demand admits of peat being prepared on a manufactur- ing scale for consumption, the process introduced by Mr. C. M. Williams at Oappoge, in Ireland, has been employed, but we fear without much profit. It consists in breaking up the fibre of freshly-cut turf, placing it thus broken between cloths, and submitting it to the action of a powerful hydraulic press. The peat on leaving the press occupies only ^ of its previous volume, and has lost about |^_ of its weight from the water which has been expelled. It is then denser than wood, although prepared from the lightest varieties of peat, and is said to have no tendency to re-absorb water. The cost of the process is not considerable, as the prepared peat can be delivered at 55. per ton ; the price of the unprepared material in the neighbourhood of the moors being 3s. 6d. per ton. Water in Peat. — The longer peat is kept and allowed to dry in suitable sheds, the more it will improve as a heating agent. The spongy character of peat enables it to retain a large but very variable quantity of hygroscopic water. Karsten observed a loss of as much as 45 per cent, by simply drying freshly-cut peat in the air, but even when thus dried the quantity of moisture retained varied between 25 and 50 per cent., which could be driven off at a higher temperature. In the latter ,case, the specimens were probably not fully dried, and in this state the peat is principally consumed in this country and in Ireland, giving rise as it must do to a loss of heat equivalent to 30 per cent. Under any circumstances, peat dried in the air retains, in virtue of its porous structure, a larger proportion of water than wood under the same conditions. Thoroughly dried under cover, it is said to contain 10 per cent, of its weight of water. Konalds found from 86 to 90 per cent, of water in freshly-cut peat, and from 53 to 56 in that dried in a room for several months, whilst peat dried in the open air only contained 30 per cent, of moisture. Messrs. Kane and Sullivan found from 10 to 24 per cent, of moisture in air-dried turf.* C. E. Bainbridge (" Proc. Cleveland Inst, of Eng.") found that a sample kept for some days under cover contained 16.4 per cent, of moisture, and that samples artificially dried regained nearly that quantity on exposure to the air. Ash of Feat. — Another constituent, which is of little consequence in wood, is sometimes so abundant in peat as to render it quite useless ; this is the ash, which is derived from two sources : first, the quantity of ash peculiar to the plants from which it has been produced, inasm'uch as this has not been dissolved out by the bog-water ; and second, the earthy matter which has been collected during the deposition of the peat. Peat-ash is essentially different in quality from the ash of wood, and varies in quantity to a much greater extent. Thus, in 100 parts of dried peat, the following quantities of ash have been observed : — Variety of Peat. Ash. Observer. Grass Peat, brownish-yellow Pitch Peat .... Young, dark-brown . Old earthy Peat Black, firm, from Neumiinster . „ „ Sindelfingen . Brown, loose, from Scheveningen sto 7 10. 2.2 7.2 2-3 ■ Karmarsh Suerseu } Schiibler • " Report on the Nature and Products of the Process of the Destructive Distillation of Peat," made to the Chief Commissioner of l^'oods, by Messrs. Kane and SuUivan, 1851. ASU OF PEAT. Quantities of Ash in loo parts of Dr ed Pent— (continued). Variety of Peat. Ash. Observer. Very old Peat, from Vulcaire, near Abbeville 5.58 ,. Long 4.61 [ Regnault Not so old, from Champ de feu ,, 5-35 Near Berlin, i. Stage .... 9-3 »» 2. „ 10.2 ■ Achard )) 3- " Black, old, from Moglin 14.4 1 Einhof Brown, young 11-3 1 Moor, in Eiohsfeld, i. sort • 21-S n )i 2. ,, 23.0 - Buchholz 3- .. 30.5 4- >. 33-0 In 41 sorts, from the Erzgebirge 1-24 Winkler In 3 vaiieties from Holland and Frieslaud 4.61-5.58 Mulder In 27 varioties from the central bog of Allen, I. 1 20 — 7.898 Kane and Sullivan in Ireland raeaa 2.62 In 3 varieties from the neighbourhood ol 3.695-4.819 Tuam, in the west of Ireland . mean 4-545 Bonalds In 9 varieties from Sohnaditzer bog, near J 5-30-37-iQ ' Wellner Sohwemsal, in Saxony . . . . mean ■ 18.47 Dumfries, Scotland 8.463 Heddle IS Peat, therefore, may contain from i to ;^^ per cent, of its weight of ash. It is said that carbonates of the alkalies are never found in this ash ; phos- phates and especially sulphates are abundant, the former being in the form of phosphate of lime. Einhof found 15-25 lime, 20.5 alumina, 5.5 oxide of iron,. 41 sihca, 15 phosphate of lime, 1.55 common salt and gypsum, in 100 parts of ash; Schubler even found 34 per cent, of phosphates in the ash of peat from Scheveningen, to the presence of which its chief value as a manure is ascribed. The ash of the three specimens analysed by Ronalds and noticed in the above table had the following composition : — I. 11. III. Potash . Soda Lime Magnesia Alumina , Peroxide of Irou Chlorine . Sulphuric Acid Phosphoric Acid Carbonic Acid . Silica soluble in Acic Insoluble Matter '. 0.813 3.666 35-854 3-170 4-423 2.56s 4-327 12-860 2-194 3-2S4 4-744 22.920 3-558 0.370 34-790 3-601 2-8oi 6-345 0-432 19-703 6.764 3-337 12.919 5-189 0.758 36-599 7.727 3-440 6.499 0.596 16.463 2.816 7.169 4.898 6.8it 100.790 98.187 98.965 I. Light peat from Ballinderry bog, taken at 4 J feet from surface. Bog 15 feet deep. II. Somewhat older peat from Claretuam bog, taken 3^ feet from surface. Bog 16 feet deep. III. Light peat from Wood Quay or Weirs' bog, taken 4J feet from surface. Bog 22 feet deep. The composition of the ashes of peat from the central bogs of Ireland has i6 ASH OF PEAT. 5 H o o o O ^, vooo cnt>ii»«oo Oso r»>o fi ^ >-■ •*■ o\0 '-:«'0 enoo ■*q*o tn o f4 R 6 6 «tA4« ■>t'dw>«i#»'+i« 8 T M \o f^ n 00 c»OD M r^M h n ^ > X X r> « V) M mvo X " M Ml to C«00 0M>0 wir-Mnoooo -r V, toe* too>Os« « "-toO N :t Ml « W1« 1*1 •+ ^00 00 vO 00 - 00 X MtOT*-o Osr-vjtow - r* OS X d d oo' ei 6 ■'no -i- 6 v» 4-vi ^ d d M c^ to d d -^ d OS n ' OS CO « 1- 1-1 « M ro M « OS w O t*» »0 M "V W300 « Wi ■+ ^ X M X n M oxvo w " H -4-M ^ 00 COVIN M l-OH>i*ir*) vjOO C» > (« CO to» osMnoxt^-w H « -H irj CO -.(■« O O* T^ « 00 O* ■* ox loioN " ■^io'**7-« «* o d 6 O'tnd 2'°'£ ° '^*° "^ d. d d PI « « CO M n « « »o «^ M <& OS N - H r* H ^ OS ^ ff* Oi Ml© o* "♦ao ** *- *o CO o t> ^ r- PI CO i2 3 «o e*x CO X vS to 00 -^ .c^OO >o M r^55 ^ lo -^ in N "S. X 1 o CO"© w> « w O^'E to CO C « « SO X "T covo r»0O to ■*sO CO o>' t> q •* oo d d d ■•o w' d *" d ■♦ d -H « vd t « d «i r^sd M«^M d N«id d OS OS ^ " vie4 0>0>^0>M M f*v)0 > v> O^toOitfltoO ff-tOH tO^O H CO >t-roO O O lOMGO 0>cOO C>> s 10 ■H to e* CO OssO CO OsX OS OS ■* X ^doo rt-M "oo O^vipiv)? «^ X «X Ox iivO «r*« "iM- X d d - N o* « a> n « h' d -ij- ►; i; d d d ^ 4 d ^ d ej d -I ^ ds ds OS TO r«tO ^vioviei Nwiff O\0 ^' so c^OnxN OSM cO-Hto o> ■ch ot -4-00 VO O f -t cooo 00 n 'fr ^tocoO cor^os— Osvnr* "2 X « w ■* » « 5i * iT S CO ^x 00 _^ m « - covq OS o.« « OS j> c« 1 o 6 do j+ *H* d OS d d d M « CO ■§. d d M pt tA d ds d -' d « CO ' 8 ve H M <0 "+00 MO -4- » v> O M X so SO N n to n c^ '^vo so x X M m •-• O OS <«.>a vO ro VOO 00 X *sO OsO tpto**OS«*Os._ « t NO I>N M d-lOO-iio -^ ^ « -. tt*"«r«i^'^": T". OS > 6 6 o^f^ 6 6 -h' m d d »' d OS d OOQO-^Otn-cooni-i ' 00 1« n n m - ^ o- I-. M ^ -« to OS M r^ covO M 00 so x>oo TO O o> — MC^VhOs^OSM Os« •*■ Wi ?£■ sag's ???:?§ 1 a N r- OssO 0^ to T^ CO Osx m J> so > *? OS ^ >o d W ■T^>0 OS M so COSO ■-< i>.so 1 OS x" o d M COC^MCO"* OmN X^OD d M cOSo" dso" M N i-i «' -■ ' OS M M n n M OS „ 00 o or-MO -ron>o o o *h ^ c«(Or«n ■♦O r-to-f*« - SO « OS os>o o r»-t-c>i»o(i o*«o^ X so N otofo-r- « - looq w ro i>oo -a -JDcc fn « so X OS M q q f en Tf->q so t>. d O O Wm ovi 6 r^6 d-tri ds d " PI dtoMe^—toMvo d« 8 X PI H n m H ^ S2S.?S.5S8.S.g.?.g d X ^ N to e*sO — to M h- X ^ to *n > tn '^ t* e^so toso to — PI CO ** OS X 6 d d CO ■! d N M - d •-' CO M 6s s do d -ct-MdiM'Ti-M^cott- CO M W I-. M OS ■+ - N OS o mO cO**w«r"-*t*« « N X ^ •f ■* e- r- r- **X so to OS >■ xn OcOC^Nr^OiO'sO Q N N ■* cox iHNX«WtoOe*r^ M XX -sl-cOPI OsOsiON OssO «^ so ■+ > X OS N - c^ n q t^ C4 X M H t^ d d - ei»;id ^« « «• M ^ch 6. d «' d OS PI OS M d CO to to to CO - M M OS OS o« M OS O "-" *0 OssO r- CO "^ «?"• O ~ CO X OstoOst^NsO MX Os« T^ OS \o so OS« -M OssO O 00 - O -4- so OtocoO "X OS toX so VO ij- on 0.«_ r-.ps'^-ffjOs-- - O CO > X "? so J:^ to ■<)- r. M so so .M « X OS d o MdMcoioM -fd W«in O^ w ■-■ dsMso "tod tosd ds Os ■-f M HI H OS CO PI OS 1? cog'0'*Mx-Mn« tox «■ 2 . ^ flSEHIHII, to Q a8.?55..SKS"5.S'e-e. 3" CO M * > ■f sq d >< d de* todsdooi-i coco'+co' ds " - - s 1 CO H PI OS r- Nt"CO« Oh mcOX OOsvi "* s-Esas-gTas-'ss-g a 0\ VO « w OsX O-sO vO X « OS OS > OS fO*" cO-wifTf-vjOs mo CO "4- CO PI so "O *^ toX OS to d OHVOcO^M-^C^iHONrO ds d d pi CO M H X d CO M too' to « -, M et M OS to « « -• OS ^ ^ ' • • • - • • • 05 M 3 ."2 -OTa *3'3 , .<< . .<>t^ £»>» J3 J J^ '33 * * '2 J ■ « m o o • ■ E-a • ' ,'il ' E S S S -0-3 •ots ," S.S > C3 ■-■3- g S. B." ga •2.S 2.3 •ii O U •° s u.S PEAT. 17 been examined in 27 specimens by Kane and Sullivan, the details of which may be found in their report before alluded to. We subjoin their result.s. I. — Light spongy surface peat, reddish-brown colour, composed almost entirely of Sphagnum, species still distinguishable ; from near Monastrevin. II. — Light surface-peat, reddish-brown colour, containing small roots of Erica, and leaves of grasses and Garex ; from Mount Lucus bog, near "Phillipstown, King's County. III. — Rather dense peat, dark reddish-brown colour, structure of moss still distinguishable ; from the same locality as II. IV. — Light reddish-brown fibrous moss-peat. Sphagnum almost unaltered, as well as leaves of Car ex and other plants, and the roots of species of Erica ; from Tichnevin, Kildare. V. — Upper layer of fibrous red bog, composed entirely of Sphagnutn, Hypnum, and other mosses ; from Derrymullen station of the Irish Amelio- ration Society. VI. — Dense peat of blackish-brown colour. Vegetable structure nearly obliterated, leaves of grasses and Garex, and twigs of hazel and apparently of birch sometimes found. Wdod of Allen, Great Timahoe bog. VII. — Light surface-peat, pale yellowish-brown. Mass very open, grained, and fibrous. Sphagnum and Hypnum readily distinguished ; from Wood of Allen. VIII. — Middle layer of same bog, deep reddish-brown colour. Mass tolerably compact, but still fibrous. Structure of the moss very indistinct. A very few roots of Erica and small twigs of birch and alder, and scales of fir ; from Wood of Allen. IX. — Lower layer of same bog. Compact and dense, deep blackish-brown, fracture earthy, appearing almost conchoidal, and exhibiting a resinous lustre when rubbed. The appearance of vegetable structure almost entirely obliterated. Wood of Allen. X. — Good compact peat, blackish-brown colour, principally consisting of moss, with a good many roots of Erica and grasses, Garex. Used as fuel in Dublin ; from Kiversdale bog, near Kinnegad. XI. — Excessively hard compact peat. Vegetable structure completely obliterated ; some pieces exhibiting a perfectly resinous conchoidal fracture. Scales of. fir-trees and twigs of birch, alder, &c., sometimes occur. A valuable fuel. Baltinoran and Rawson bogs, near Kinnegad. XII. — Very dense dark reddish-brown peat. Vegetable structure only occasionally perceptible; from Anadruce and Cloncreim, on the Royal Canal. XIII. — Rather dense peat, of a dark reddish-brown colour. Structure of Sphagnum, very indistinct, but leaves of the flag, and stems and roots of Erica occur in a perfect state. Structure compact ; from bogs of Rath- connel, Wood Down and Great Down, near MuUingar. XIV. — Upper layer of fibrous bog. Mass spongy and of a yellowish- red colour. Composed of almost unaltered Sphagnum, with occasional roots of Garex, Erica, ifec., from the neighbourhood of Banagher. XV. — Rather compact peat, of reddish-brown colour. Vegetable structure very perceptible, but impossible to distinguish species ; roots of Erica abundant, but the greater part evidently derived from moss. Same locality as XIV. XVI. — Still more compact peat than XV., consisting of fibrous or red bog, colour light reddish-bi'own. Structure of mosses still visible, but species cannot be discriminated , roots and leaves of Garex exceedingly abundant. Same locality as the two preceding. XVII. — Light surface-peat, of a pale reddish-brown. Mass spongy and composed of almost unaltered Sphagnum, with a few stems and roots of c 1 8 DENSITY OF PEAT. Erica ; from the bogs of Clonfert and Kilmore, at the mouth of the river Suck, near Banagher. XVIII.— Rather compact peat, of a light reddish-brown colour, fibrous, but passing into black peat. Sti-ucture of mosses still perceptible. Abundant remains of Carex and grasses ; from the same locality as XVII. XIX. — Exceedingly dense dark blackish-brown peat, fracture earthy, sometimes conchoidal. Vegetable structure almost completely destroyed ; but when apparent, remains of Carex, grasses and Erica abundant ; from Athlone bog. XX. — A rather dense peat, of a blackish-brown colour, in which the structure of moss is no longer visible, but abounding in remains of Carex, grasses and roots and stems of Erica ; from Curragh or Clonbourne bogs, near Shannon Bridge. XXI. — A dense peat, of a dark reddish-brown colour. Eemains of Carex and grasses very abundant, but Sphagnum much compressed and structure very indistinct ; from bogs along the Shannon. Used in steamers plying on the river. XXII. — Light fibrous peat, of reddish-brown colour, evidently formed of a great number of plants. Structure of moss very distinct. Species of Sphagnum and Hypnum distinguishable. Remains of Carex and grasses, with roots of Erica, and bark of birch, and probably alder-twigs abundant. Same locality as XXII. XXIII. — Very dense peat, of a blackish-brown colour. Mass compact. Vegetable structure very indistinct. Remains of Carex abundant, and roots of Erica frequent. An excellent fuel. Same locality as XXII. XXIV. — ^A very dense blackish-brown compact peat. Vegetable structure almost obliterated. Fracture earthy. Full of tubes of the bark of hazel, birch, and alder, and occasionally scales of pine-bark, and leaves of Carex and grass. Same locality as XXII. XXV. — A rather dense reddish-brown peat. Structure very indistinct. Carex leaves altered, and occasionally a few fragments of twigs and roots. Same locality as XXII. XXVI. — Rather compact and moderately dense peat, of a dark reddish- brown colour. Structure of moss almost obliterated. Abundance of leaves, stalks and roots of grasses, Carex, &c. Same locality as XXII. XXVII. — Dense jet-black peat. Structure of moss completely destroyed. Fracture earthy, tending to conchoidal, assuming resinous lustre when rubbed. Abundance of remains of Carex leaves, and a very few fragments of bark, apparently of hazel. Same locality as XXII. Density of Peat. — The weight of peat depends on its state of dryness, and its age. Karmarsh gives the following relative weights for different kinds of Hanoverian peat : — i. Light-coloured, young grass peat, nearly unchanged moss, 0.113 to 0.263. 2. Young brown and black peat, an earthy matrix intersected with roots, 0.240 to 0.600. 3. Old earthy peat without any fibrous texture, 0.564 to 0.902. 4. Old peat, pitch peat, 0.639 to 1.039. Moulded peat from Griesheim (near Darmstadt), of good quaJity, has been found to weigh 0.706, so that i cubic foot would weigh on an average 22 lbs. and 100 bricks (at 56 cubic inches), 123.5 lbs.* After incineration, these leave a mass of ash, which, although less in bulk, retains the form of the brick, and is very considerable in quantity. Sir R. Kane estimates the specific gravity of light surface-peat at about 0.400, and from this it increases, with the compactness of the substance, to nearly the density of coal. A cubic yard weighs, packed closely in sods, * 1000 pieces of Griesheim peat are calculated at 74,300 c. f. and weigh 1170 lbs. • „ „ Pfuugstiidt „ „ 75,600 „ „ 820 „ „ „ „ best and driest „ 49,000 „ „ 660 „ ELEMENTARY COMPOSITION OP PEAT. 19 about 900 lbs. The densest turf will weigh as much as 1,100 lbs. per cubic yard, whilst the lightest may not weigh more than 500 lbs. Compared with coal in fragments as employed in the furnace, peat is about j as dense. A cubic yard of coal averages about 1 3 cwt. The maximum specific gravity of peat from the series of 27 specimens of all kinds and characters from the great bogs in the centre of Ireland, as given, pp. 17, 18, by Sir E,. Kane and Dr. Sullivan,* is 1.058, and the minimum 0.235 > ^^^ greater number of specimens being, however, below o.6.t The quantity of water contained in these specimens, after being dried in the air, ranged between 10.446 per cent, in a specimen taken from the middle layer of a bog, and 33.270 per cent, in a very dense compact specimen, in which vegetable structure was very indistinct. The mean quantity in the 27 specimens was 21.6. A cubic foot of the earthy peat examined by Karmarsh gave nearly 3 lbs. of ash ; a quantity which must be very prejudicial in many of its appli- cations ; partly from the dust which it makes and the space it occupies ; J and partly by its chemical action in smelting processes, destroying the bars of grates, besides decreasing, of course, the quantity of combustible matter. The conditions under which peat is produced would have a tendency to in- crease the amount of carbon above that contained in woody fibre. Regnault and Mulder have both examined the elementary composition of difi'erent varieties of peat ; and the following are their results, after deducting the amount of ash stated in the previous table : — Localities. Carbon. Hydrogen. ' Oxygen. Analyst. SP-S7 5.96 34-47 Eegnault. 60.40 5.86 3364 Mulder. Long 1 60.06 6.21 33-73 Regnault. 60.89 6.21 32.90 Mulder. Champ de Feu ... 1 60.21 61.05 6.45 6.45 33-34 32.50 Regnault. Mulder. Fnesland 59.42 5.87 34-71 60.41 5.87 34.02 Holland 59-27 S.4I 35-32 »» There is a very small quantity of nitrogen in peat which is recognized by the ammoniacal vapours it produces when heated. It would thus appear that peat differs essentially from wood in elementary composition. The former may be viewed as consisting of carbon and water in equal proportions by weight, whilst in the latter, the entire amount of oxygen being supposed in combination with hydrogen to form water, we have the following relative proportions in 100 parts : — Carbon Hvdrogen Water 60 2 38 or an excess of 10 per cent, carbon and 2 per cent, hydrogen over that con- tained in dried wood, whilst the amount of water is reduced 12 per cent. The following analyses of specimens of Irish peat show also the amount of * "Report on the Nature and Products of the Process of the Destructive Distillation of Peat, considered especially with reference to its Employment as a Branch of Manufacturing Industry." London, 1851. t For details of these, see Table, p. 17. j In a fire, which converted 320 lbs. of water into steam in g hours, 240 lbs. of peat were consumed. The ash of this, calculated at 20 per cent., would leave 48 lbs. daily on the hearth and amount in the year to 175 cwt., the removal of which would be attended with much expense and trouble. C 2 20. HEATING EFFECT OF PEAT. nitrogen which they contain. The ash was deducted in calculating thesft results so as to exhibit the actual composition of the organic matter : — Civrbon. Hydro- gen. Oiygen. Nitro- gen. Ash. Surface Peat, Phillipstown (Sp. 11. p 17) Dense Peat, Phillipstown (Sp. III. p. 17) Lis;ht Surface Pnat, Wood of Alk-n (Sp. VII. p. 17) - . - - Dense Peat, Wood of Allen (3p. XX. p. 18) Tichnevin Peal (Sp. IV. p. i;) . Upper Shannon (Sp. XVII. p. 17) Upper Shannon (Sp. XXIV. p. 18) . rCilbeggan, Westmeath Kilbaha, Clare ... Cappoge, Kildarc .... 58.694 60. 476 59.920 61.022 60. 102 60018 61.247 61.04 56.63 51-05 6.971 6.097 6.614 S-771 6.723 5875 5.616 6.67 6.33 6.85 mean. '32.883 1. 4514 32. 546 0. 8806 32.207 1 1.2588 32.400 0.8070 31.288 1.8866 33.152 0.9545 31.446 1.6904 30.46 34-48 39-55 1.992 ' 3-305 2-745 7.898 2.629 2.474 2.976 ■1-83 8.06 2.25 CD I CO f a ?^ ■ E: The following may also be added to the list ; in these the ash is not deducted : — Oohta, in Eastern Russia . j Peat, 44 ft. from surface, Tnam, Ireland I iJ 32*''- >» »» »J ; >! 44 f- !I >> !> 39.084 57.207 58-306 59-550 5-655 5.821 5.502 51.088 28.949 29.669 28.414 3.067 2.509 1-715 6.04] 5.122 3-695 4.819 Woskre- senskj These results coniirm generally the above remarks. It appears from the table of ash analyses, that the amount of sulphate of lime and phosphoric acid does not depend on the position occupied by the peat in the bog, but rather on local circumstances ; that during the formation of peat the greater part of the alkali "and phosphoric acid originally contained in the plants has been removed ; and that the amount of silica is very small, especially, in the fibrous varieties. The proportion of carbon and hydrogen contained in different specimens of peat does not vary much, although the lower layers generally contain a little more carbon than those near the surface. Use of Peat. — Heating Effect.* — The practical application of peat for heating operations depends greatly on the amount of moisture it contains, and the degree of condensation to which the peat has been reduced has also an important bearing on its economic value, affecting as it does the bulk which has to be transported and its power to resist handling and transport. Karsten states that for evaporative and boiling operations 2i parts by weight of peat are equal to i part by weight of coal 4 „ volume „ „ I „ volume „ This is borne out by some experiments quoted by D. K. Clarke (" Fuel and its Combustion," &c.) from a paper by Mr. W. Anderson, of Erith. Mr. Anderson reports some comparative experiments carried out at St. Peters- burg on the evaporative effect of coal, wood, and peat in double-flued multi- tubvilar cylindrical boilers. The fire-grate area was 30 square feet and the heating surface 696 square feet. The peat was of compact quality, and had been moulded by hand into 4-inch balls and air-dried until the moisture did not exceed 14 per cent. * Refer to " Proc. Inst. C.E.," vol. xxxviii.: " Peat Fuel Machinery," by J. McCarthy Meadows. Also to "Proc. Inst. C.E.," vol. xli. (1874-75), P- 202. COAL. 21 Locality and Description of Fuel. Fuel consumed per hour. Water evaporated per hour at 100.4° F. Water evaporated at 212° F. per lb. of Fuel. Abouchoff Steel Works, 1870-74. Superior Coal Inferior „ . . . Wood cut I year, etill damp . Wood dried artificially .... Peat 450 515 796 538 49-5 51.0 38.6 40.4 7-57 6.76 3-25 5.00 4.26 The average of the results obtained at Erith and St. Petersburg with coal was 8.55 lbs. water evaporated per lb. coal, which shows the relative value of peat to be one -half that of coal. C. E. Bainbridge quotes some tests with Thompson's calorimeter, which give a better result than the above — viz. : Peat in its usual state showed a calorific power = 4-675 „ dried „ „ =5-94 But the following remarks from Crookes and Rohrig's Metallurgy are strictly to the point : — " I lb. of dry turf will evaporate 6 lbs. of water ; now, in i lb. of turf as usually found there are | lb. of dry turf and \ lb. water. The | lb. can only evaporate 4^ lbs. of water ; but out of this it must first evaporate the \ lb. contained in its mass, and hence the water boiled away by such turf is reduced to 4^ lbs. The loss is here 30 per cent., a proportion which makes all the difference between a good fuel and one almost unfit for use. When turf is dried in the air under cover, it still retains one-tenth of its weight of water, which reduces its calorific power 12 per cent. ; i lb. of such turf evaporates 5^ lbs. water. This effect is sufficient, however, for most of the purposes for which it is used ; the further desiccation is too expensive and too troublesome to be used except in special cases." FOSSIL FUEL, OB COAL, The steady and gradual operations of nature, at the present day, supply certain districts with a stock of fuel of no mean quality, by the constant interment of the lower kinds of vegetation in the manner already de- scribed ; but in the earlier periods of the earth's history far more exten- sive stores of invaluable combustibles were laid up for the future use of mankind. The most valuable of all the species of fuel is coal, and its discovery and application have been attended with increased prosperity in all those countries which are so fortunate as to possess it. Coal is a dark-brown or black mineral, of no great degree of hardness, varying from 1.2 to 1.8 in specific gravity, burning with a more or less brilliant flame and much smoke when ignited. It occurs in horizontal or more or less inclined layers, alternating with clay, and frequently with ironstone, chiefly in the geological formation which, from this circumstance, has been named the Carboniferous, and which takes position in the series of sedimentary deposits between the lower Silurian or primary fassiliferous formations on the one hand, and the New red sandstone on the other. Anthracite, the oldest species of coal, is also found in the most recent members of the transition formations ; whilst brown coal, the youngest variety, occurs in the chalk. There appears no reason to doubt the vegetable origin of coal. The gr.idual metamorphosis of woody fibre into coal can be traced chemically, 22 VEGETABLE ORIGIN OF COAL. step by step, through the various stages ; upright fossil trees, with their roots resting in seams of coal, testify to their growth upon the site in which they remain carbonized, whilst modem transformations of forests into peat- bogs, in which the trees remain erect, afford the strongest analogical evidence of the manner in which many of the ancient coal-fields may have been produced. Botanists who have paid particular attention to the fossil flora of these deposits are generally agreed in ascribing them to the accumulation and gradual decomposition of ferns, some of which were arborescent, and to vegetable forms belonging to Ccclamites, Lepidodendra, Sigillarioe, and StigmaricB ; palms, though rare, are sometimes found. Altogether not less than from 200 to 300 species of plants have been found in the coal measures. The character and habits of these plants would indicate that a very different temperature and climate, and indeed an altogether different distri- bution of land and water, must have existed at the time of their growth and subsequent interment. They belong to a class of vegetation which flourishes in an extremely moist, warm, and equable climate, with the absence of any severe cold ; the circumstances and meteorological conditions under which they grew, therefore, must have been very different from those which characterize the coal districts of the present day. A tropical climate was at one time considered essential to the growth of these vegetable forms, and a very large excess of carbonic acid in the atmosphere above that contained at the present time has been assumed in explanation of their gigantic development. Although closely allied to tropical plants, those of the coal formation are still so distinct, that the former assumption does not appear necessary ; indeed the flora of the southern coasts of New Zealand, situated in the 46th degree of latitude, is stated to bear the strongest resemblance to that of the coal formations. From considerations of this kind, it has been reasonably inferred that, at the time of the carbonaceous deposits, the northern hemisphere was pervaded by a great ocean interspersed with numerous islands of small dimensions, bearing insular or submarine volcanoes, a combination of geographical circumstances not unfavourable to the growth of a flora like that from which these deposits have been formed. Alternate elevations of sea and land, islands springing up by volcanic agency from the bottom of the ocean, might cause the waters to overflow and submerge the less elevated lands, and bury with them the forests and vegetation under layers of mud and sand. A series of alternate changes of this character might possibly account for the various coal deposits. By some it has been supposed that the coal-fields resulted from collections of drifted timber deposited in the deltas of rivers at the time of their over- flow. This supposition is supported by the fact, that many of the large rivers of North America, particularly those which flow from south to north, are known to tear up and' carry away, on the breaking up of the ice, numbers of large trees, which, having been completely soaked by long immersion in water, become heavy and sink, and are gradually buried in the deltas under mud, sand, and the debris of rocks, or are drifted by the currents of the ocean to more remote and quiet localities, there to undergo the process of carbonization. Heat and moisture, with the partial access of atmospheric air, appear to have been the active agents in carbonizing the buried vegeta- tion, assisted at a later period by immense superincumbent pressure in consolidating it. Coal is met with in more recent geological formations than the one to which it has given its name. The deposits therefore differ considerably in age, and two distinct species of coal may easily be distinguished, as well by their physical as chemical peculiarities. All coal that occurs above the chalk CUMULATIVE KESOLUTION. 23 is of comparatively recent origin ; the process of decay is less advanced, and it is evidently much more allied to wood, than that which lies below the chalk. The former is called hrovm coal, or lignite, whilst many varieties of the latter are classed together under the common name of bituminous or pit-coal; that variety in which the carbonization is most complete being called anthracite. Whilst the entire structure of the wood is retained almost unchanged in the first, it has disappeared completely in the last two, with the exception of a few rare impressions of plants. All the varieties may be viewed as derived from woody fibre, the carbon of which for the greater part has remained, while the other elements have gradually diminished and dis- appeared in proportion to the age of the formation, until in the last product, anthracite, hardly anything but carbon is left. This is the result of a process which may be distinctly traced by comparing the elementary compo- sition of the difierent members of the series. The composition of woody fibre in 100 parts, as given at page 10, corre- sponds closely with the formula wCTgHjdOj. An important feature in the progressive decomposition of buried wood, is the production of carbonic acid from the elements of the wood. In the case of the formation of brown coal, where atmospheric oxygen is not so com- pletely excluded, this element combines also with a portion of the hydrogen ; this does not occur in the formation of coal. In the latter case, the elements of woody fibre are simply resolved into the four products : carbonic acid, water, light carburetted hydrogen, and coal. In the former, the mouldering process is predominant, but decay (eremacausis) also performs its part ; the formation of coal, on the contrary, is exclusively a mouldering process. It is more than probable that the carbonic acid accompanying the mineral waters of the carboniferous deposits, is produced at the same time as the light carburetted hydrogen, which has been observed to constitute the chief mass of the fire-damp of coal-mines. Cumulative Besolution. — Supposing, for the sake of simplicity, that n = I in the formula of woody fibre, the primary or fundamental change which woody fibre undergoes is one of successive dehydration. Thus iiCeH^A - (n - I )H,0 = nO,H,„,,0,„ , , represents the formation of every possible stage in the removal of the first HjO ; and, when n becomes infinite, the removal will be complete, and we shall have the body whose formula is C^HjO,. Proceeding as before, nC3H,0,-(n-i)H,0 = nC,H,n^An + „ which becomes CgHjOg when n is made infinite. In this manner, the additional hydrates C^II^Oj and CgH^O will be obtained, and then inter- mediate stages may be similarly represented. The limit of the entire series is of course nCg, a pure carbon in one of its polymeric forms ; but it is un- likely that this point is ever really attained in any process of natural decay, or natural or artificial destructive distillation. The whole process, which is very common in every department of chemistry, is called by Mills " Cumu- lative Resolution." The actual work of dehydrating cellulose and its congeners leads eventually to carbon and water as the principal products. It is, however, well known that, with increasing complexity or numerical value of formula, proneness to variation in chemical change increases. Accordingly we find that, in the destruction of cellulose by heat and decay — or, in the language of symbols, as n is made infinite over and over again — the number of bye-products increases, and the main or stem-substance eventually ceases to be exactly constituted in the ratio C^ : mH.fi Coal, for example, always contains H in excess of this ratio, known under the name of " disposable hydrogen ; " and, in the formation of coal and peat, hydrogen, carbonic acid, and marsh gas are all given oif. According to Mills, the formation of bye-prOducts is mainly 24 BROWN COAL OR LIGNITE. observable at or after the period when the stem substance has the com- position CjHgOg. Coal is met with in three distinct geological formations. Commencing with the lowest, we find it : 1. In the coal measures, which may be subdivided into the older transition series (anthracite), and the younger coal. 2. In secondary formations, both in the older members of the new red sandstone (Keuper of the Germans), in the limestones of the oolite group which constitute the Jura, and in the more recent chalk. 3. In tertiary deposits, as fresh-water limestone, shell limestone, &c., with hrown coal. Brown Coal, or Iiignite. — The coal of the tertiary formations is ii.ot always uniform in appearance. In some kinds, the vegetable remains are so well preserved, their structure so distinctly retained, even the more tender parts, as leaves and fruit, so little altered, that a botanical diagnosis of the antediluvian plants has been undertaker? with success. They consist of flattened stems, crossing each other in all directions, of a more or less dark colour, soft and mellow in consistence when freshly quarried, but becoming brittle by exposure, the fracture following the direction of the fibre of the wood. This variety is known by the name of lignite, fossil and improperly bituminous wood. Bovey coal (from Devonshire), and the coal of the Wetterau (Salzhausen, Laubach) in Germany belong to this class (it is also called, from its texture, fibrous brown coal). In other kinds, there are only occasionally distinct indications of vegetable structure, and they appear throughout as a stratified mass, of a dark colour, nearly black. They have an earthy fracture and are called earthy brown coal; to this class the coal of Meissner, near Cassel, belongs. Those varieties in which the fracture is conchoidal and the structure more dense have been distinguished as conchoidal brovni coal ot pitch coal. Lignite is frequently mixed with these, and both kinds are often present in the same specimen. Although sometimes occurring at the surface, these fuels are usually obtained from a considerable depth. Water in Brown Coal. — Fresh from the pit, the lignites are impregnated with water, which evaporates on exposure to the air, the amount of evapo- ration depending on their degree of porosity and the temperature. Eeinsch found lignite, from the Bavarian Upper Pfalz, to contain 43, and earthy brown coal; from the same locality, to contain 30 per cent, of water. The amount of moisture in brown coal is, however, generally greater ; at least Varrentrapp found that fresh coal, from Helmstedt and Schoningen, contained 48 per cent, of water. After being completely dried (when a great reduction of volume occurred), these coals re-absorbed 8 per cent, of moisture. Coal of this kind, kept for some time piled up, contained 29 per cent, of water; after exposure to the ail' in summer, 20 ; and in a warm room after four weeks, 8 per cent. Ash. — The amount of ash in brown coal itself is not very large ; it is, , however, frequently increased to an injurious extent by the infiltration of water containing salts, and by an admixture of earthy matter, as will be seen from the following table : — ASH OF BEOWN COAL. 25 Variety of Brown Coal, or Lignite. Ash. Observer. Per ceut. Lignite from Aussig . » J) • 5-35 5-51 Bohemian 1 Hegendorf „ Neuendorf .... 6.93 5-13 -Balling ,, Coulang . 1.50 Earthy from Griinlas . . . . 6.66 Bavarian Ob.-Plalz „ „ Verau 10.00 . Reinsch Lignite ,, „ • 340 „ „ Greece . 9.02 „ „ Usnach 2.19 „ „ Cologne . Earthy brown coal from Dax 549 4-99 Eegnault 1 „ ,, „ Buuches du Rhone . 1343 1 „ „ „ Nieder-Alpen . 3.01 f ;; ilSSr'W--- • 1 1547 2.43 „ „ from Hirachberg "j j 0.81 1 Cassell Pitch coal „ „ [r>- 1 1.1 . Middle sort „ ,, hEmgknhl Lowest sort ,, „ j 2.76 3.20 4.92 Kiihnert Pitch coal from Habiohtswald \ J. .1 ,1 1-33 3-33 Stillberger coal (Siihrwald) . 6-95 Lignite from Hirsohberg iS9 / ,, Iceland 8.8 „ ,, (another sppcmien) 27-5 / J, Utweiler 0.9 From Duren. ,, Grube Urwelt 4.6 on the left bank h " 5 » )) • 27.05 of the Rhine ,, Friesdorf 1.69 ,, „ . . . 14-9 \ Karsten ,. Pntzohen 44 ' Near Bonn, on the right bank < ,, Stossclicn 174 144 28.2 of che Rhine ,, Ordberg 432 580 Coal from Schbningen ti . -.i „ Helmetadt | Brunswick . - 7.8 8.4 } Varventrapp Slate coal from Azberg ,, „ Aga Reuse . 60 [ Reinsch Earthy lignite from Wigan . 4-95 J. A. Phillips „ ,, Conception Bay 7-49 ) Admiralty I Coal Lignite from Sandy Bay, Patagonia 13-29 ,, Talcahuano Bay 6.92 ) Investigation ,, Artern, Germany 1,16 Kremers The amount of ash, even in the same deposit and in different parts of the same piece, varies more than is the case with peat ; as may be seen from Karsten's experiments. The general conclusion to be drawn from these results is, therefore, that the amount of ash in brown coal varies from i to 50 per cent. In most cases, however, it is not less than 5, and seldom above 10 per cent. Reinsch found in the ash of lignite, from Verau : Sulphate of Lime Hyposulphite of Potash Hyposulphite of Lime . ProtoBulphate of Iron Sand . 3-6 1-9 25.4 SO. 20. 100.9 26 COMPOSITION OF BEOWN COAL. The ash of earthy brown coal yielded Sulphate of Lime Hyposulphite of Lime . Protosulphate of Iron . Sand. . . . . . 3- 7- SI- 33- Yarrentrapp found in the ash of brown coal from Brunswick : Sulphate of Lime Magnesia . Alumina Oxide of Iron Carbonate of Potash Silica and Clay . U.S7 S-78 2.64 19.27 99-34 Brown coal, such as that of Orsberg, consisting of one half mineral matter, cannot be considered fuel, but can be made use of for other pur- poses (see Alum). Ifitrogen in Brown Coal. — In addition to the ash and the elements of wood, brown coal contains from 0.5 to 1.5 per cent, of nitrogen, which has not been separately estimated in the following analyses : — ■ Brown Coal contains (in addition to the Ash, ; see page 25) Carbon. Hydro- gen. Oxygen & Nitrogen. Observer. Earthy, from Dax 69.52 S-S9 19.90 ) „ Bouches du Rhone . 63.01 4.58 18.98 \ Eegnault „ Nieder-Alpen .... 69.05 5.20 22.74 ] Earthy, consisting of stems, from Meissner 70.12 3-19 759 ,, pitch coal from Meissner . 56.60 4-75 27-15 „ „ ,, Bingkuhl, Hirschberg. 60.83 4-36 24.64 „ ,, „ Habichtswald . 57.26 4.52 26.10 ,, lustrous coal, Eingkuhl 66.11 4.82 18.51 Kilhnert ,, allied to pitch coal, Habichtswald 54.18 4.20 26.98 „ lowest Tcin, at Eingkuhl . 52.98 4.09 21.91 ,, middle ,, ,, ... 54.96 4.01 22.31 ,, Stillberger 50.78 4.62 21.38 Helmstiidt, Prince William mine 68.57 4.84 19.87 ,, ,, another mine , , Schoningen, Treue mine . 67.88 63.71 6.85 S-07 17.46 22.79 Varrentrapp „ „ another pit 64.80 4-54 23.12 Lignite, from Eingkuhl . 51.70 5-25 30-37 Kiihnert ,, Greece 60.36 5.00 25.62 ) ,, Cologne . 63.42 4-98 27.11 \ Regnault „ Usnach . SS-27 5.70 36.84 ) ,, Laubach . 57.28 603 36.10 Liebig Earthy brown coal, from Wigan 80.21 6. -^o 8.54 J. A. Phillips ' ,, ,, ,, Conception Bay 7033 5-84 16.34 ] Admiralty Lignite from Sandy Bay, Patagonia 62 19 5.08 19.44 Coal „ Talcabuano Bay 70.71 6.44 16.93 Investigation The actual organic portion of brown coal in its different modifications according to the analyses of Eegnault is therefore as follows : — Locality. Character. Carbon. Hydro- gen. Oxygen & Nitrogen. Lignite, fossil wood, or fibrous " brown coal Greace Cologne . Usnach Laminated, black, with indi- cations of organic structure Ligneous texture, friable, brownish-red in powder Fossil wood, woody texture, very hard .... 66.36 66.04 56.50 S-49 5.27 5-83 28.15 28.69 37-67 COMPOSITION OF BROWN COAL. 27 Analyses of B.egiaaa]t^contin«ed. Locality. Character. Carbon. Hydro- gen. Oxygen i Nitrogen. Earthy brown Dax . Fine black, irregular fracture, no ligneous texture . 7^.18 5.88 21.14 Bouchesdu Rhone Slaty, black and brilliant, no coal, 01' perfects ligneous texture 72. 78 S.2q 21.93 lignite Mont Meissner . Brilliant, concboidal fracture 72.00 4-<3^ 23.07 \ Basses-Alpes Black, fatty lustre 71.20 5-36 23-44 Pitch coal, con- \ choidal brown Ellnbogen Compact, homogeneous, frac- coal or lignile [ ture conchoidal 76.58 7.8s 15-57 passing into Cuba. Black, like velvet, fatty lustre 77.88 7-55 H-57 bitumen The mean of these experiments, after deducting the ash, would lead to the following general composition for the organic portion of the varieties of brown coal : — Carbon. Hydrogen, Oxygen and Nitrogen. Fibrous brown coal Earthy „ Pitch „ . . 63 72 77 5 5 7-5 32 23 The whole of the oxygen being supposed combined with hydrogen to form water, the composition would then be nearly as follows : — Carbon. Hydrogen. Water. Fibrous brown coal Earthy „ Pitch „ . . 63 72 77 I 2 5-5 3^ 26 17-5 The weight of air-dried brown coal varies within narrow limits ; the specific gravity of the specimens of lignite examined by Regnault varied from 1. 100 to 1.85 ; that of the earthy coal, from 1.254 to 1.276. Kiihnert found the latter to vary from 1.310 to 1.436, whilst lignite had a specific gravity of 1.279, ^^^ *h6 lignites examined by the ofiicers of the Admiralty Coal Inves- tigation varied from 1.291 to T.321. A cubic foot of brown coal will there- fore weigh on an average 80 lbs., but the absence of uniformity in the nature of the substance hardly admits of applying to a larger quantity the weights obtained from experiments on a small scale. The numbers found clearly show that the variations are independent of the amount of ash.* TJse of Iilgnite. — From a paper by M. Sylvain Periss6, in the Memoires et Compte-rendus des travaux de la Societe des Ingenieurs Civils of Paris (No. 28, 1874, p. 768), it appears that at the date of his communication the use of lignite in metallurgical operations connected with iron manufac- ture was carried out on an extensive scale in Tuscany. The lignites used contained from 40 to 50 per cent, of moisture and 15 per cent, of ash. They were air-dried, and used in the gas-producers connected with Ponsard furnaces for reheating and puddling iron and for firing boilers. With a turn- out of 6,800 to 7,000 kilos, per furnace per twenty-four hours, the consump- * In the grand-duchy of Hesse brown coal has been found at the following places : — i. In Upper Hesse, near Lauterbach or Zell, at Laubacb (Hessenbriicken), Salzhausen, Friedberg (Dorheim, Bauemheim), Eberstadt, Obererlenbach, Griinberg (Zeche Buderus). 2. In the pio- vince Starkenbui-g, near Seligenstadt. 28 PIT COAL. tion of lignite was 585 kilos, per ,ton of iron charged or 638 kilos, per ton of finished iron. On railways in Italy, it was ascertained that when the lignite did not contain more than 1 5 per cent, of moisture, two tons of it were equivalent to one ton of coal briquettes. Prof. Tunner, of Leoben, Austria, discussed the use of lignite in the blast-furnace before the Iron and Steel Institute in 1882 ("Jour." vol. i. 1882, p. 96), but from the experience gained in Austria in that application of this fuel he recommended the use of a mixture of brown coal and ordinary coke or coke made from the small of brown coal mixed with some good coking-coal.* At the steel works at Teplitz, in Bohemia, it appears, from a paper by K. "Wittgenstein and A. Kurzwernhart (in " Jour. Iron and Steel Inst.," No. ii. 1882, p. 451), that for the daily manufacture of twenty charges of six to six and a-half tons each of steel, by the Bessemer process, about 1,320 cubic metres of brown coal were used and 1.6 cubic metres of coke. The brown coal was used for melting the charges of iron- in Siemens' regenerative furnaces, for heating the converters, and for raising steam ; grates of the shelf and step-grate form being successfully used. When wood is not available, lignite is often used in Austria in the salt- works for evaporating the brine. The heat required for this purpose is not intense, so that the ash is not apt to form clinkers in the furnaces. The plan of compressing lignite into blocks, with subsequent drying of the blocks, is recommended for Prussian lignites by R. A. Schultz (see Zeit. fiXr Berg- Hutteii- unci Salinenwesen, vol. xxiv. p. 234 ; also " Proc. Inst. C. E.," vol. xlviii. p. 349). Several plans are proposed, and the author gives statistics of cost of the process and plant and of the value of the pro- ducts. The following table sums up the general properties of the different classes of this fuel : — ■ Wet Coal as Hand-moulded W£t-pressed Dry-pressed raised. Blocks. Blocks. 1.26 — 1.32 Blocks. Specific gravity 1.22 — 1.29 1.24— 1.31 1.20— 1.22 Proportion of water ppv cent. 42.30—47.00 32.10—35.40 26.60 — 30.00 17.20—21.50 Proportionof asliper cent. 6.00—9.30 7.70—13.80 8.60—10.50 10.00—14.20 Heating power 183 — 209 179—223 231-287 254—315 Cohesive power — 0.17 — 0.22 0.38—0.45 0.68 — 0.74 Cimdensation in volume per cent. . — .S64 50.1 56.6 Value per i hectoli re of coal in pence n-2h 3-34 4i-6i 61-74 MIBTEEAL OE PIT COAL. Coal in a Geological point of view. — Geologically speaking, coal is a stratified rock, always found in beds interstratified with other stratified rocks, clays, sandstones, and limestones. The only difference between coal and clays, sandstones and limestones, is, that whilst they are formed prin- cipally of mineral matter merely enclosing organic remains, coal is formed principally or entirely of organic remains. In some few instances, the organic remains may have formed parts of animals, but in the greater number of cases (so great as to be nearly * .4n important paper on this subject by F. Frederic! in Oest. ZeitMhr. f. Berg. u. Hutt, 1882, Nos. I to 5, is noticed in "Jour. Iron and Pteel Inst." No. i 1882. p. 286. FORMATION OF COAL. 29 universal) the remains are those of plants. These vegetable remains, having been deposited in thick beds or layers, each layer extending over an area . sometimes of many square miles, were covered up by other beds of sand or mud, and subsequently converted into coal. How this conversion took place is a question for the chemist to decide. Pressure no doubt aided it, and some degree of heat, but -perhaps not a greater degree than would arise from the decomposition of the plants themselves. The thickness of the beds varies from a mere film or layer of a ^ inch in thickness up to 3 or 4 feet. No single bed of coal, probably, is ever thicker than 3 or 4 feet, and rarely exceeds half that. Where a seam of coal reaches 8 or 10 feet, and a fortiori where it reaches 30 or 40, it is composed of two or three or more beds resting directly one on the other, or separated by thin layers of clay or earthy matter, which are commonly called "partings." These thin layers of earthy matter — fine mud originally — are so frequent as to be almost universal in all beds of coal whenever they are traced over any distance — and they sometimes, even when not more than an inch or two in thickness, extend over -areas of many square miles. They are the result of tranquil deposition of sediment in water, and prove the coal to have been under water at the time of the formation of the " parting." Beds of coal, which in one locality come together, resting one on another directly or with only the intervention of a " parting," are in other places separated by many feet, or sometimes even many yards (30 or 40, for instance), of interposed beds of sandstone and clay. The same would be found to occur in all sedimentary stratified rocks, if any one or two beds of them were traced accurately over wide areas in the same way as beds of coal are by mining opera- tions. There is, in short, no peculiarity or mode of occurrence in beds of coal which is not common to other beds of regularly stratified sedimentary rock. We should, therefore, be at once inclined to decide that the materials of coal had been deposited under water, having been drifted into their present position, become water-logged and sunk, just as the materials forming sand- stones and clays have been drifted and sunk to the bottom, were it not for some other circumstances which make it probable that coal W!is often the result of the deposition of the remains of plants on the spot where they grew, and that that spot was dry land. Every bed of coal, for instance, has under it a bed of clay — usually fire-clay, but sometimes arenaceovis, or even sandstone itself — crowded with the remains of plants that are now known to be roots, and the roots of stems that are so frequently found associated with coal that they evidently contributed largely to its formation. Botanists tell us that these stems were not those of aquatic, but of land plants. Upright stems, moreover, of trees have been found under such circumstances as almost to prove them to be in the position of grawth, and in some beds of coal that have been worked by "open work" (quarrying, that is to say), stools of trees have been found in abundance close together in the substance of the coal, and in ranks one above another in its different layers. It is supposed, therefore, that many beds of coal were formed, not by drifted plants, but by plants that fell and died on the spot where they grew, that spot being afterwards depressed beneath the level of water from which the sedimentary masses of sandstone and clay were deposited upon them. It is probable that coal was the result sometimes of one, sometimes of the other method of accumulation. The varieties of coal may depend on the varied nature of the plants that coraposed it, the various circumstances attending their deposition, or the varied conditions under which the beds have subsequently been placed. If coal were formed under water, mud or earth may have been deposited along with it ; if it grew above the level of the water, occasional floods may have brought in earthy matter over and among it. This we see in our peat-bogs 30 MINEEALOGICAL CHAEACTEES OF COAL. at the present day. Many of the clays or shales in the " coal measures " contain a greater or lesser amount of carbonaceous matter intimately mixed up with them, and this occasionally to such an amount that they will for a time support combustion and give off gas. This may be observed often in our parlour fires, in what are called " slates," but which ought to be called " shales," and which in Staffordshire and other coal fields are called " batts " or " basses." Some coals, moreover, have such an amount of earthy matter mingled with them that they support combustion but indifferently when compared with other coals. It hence arises that there is every possible gradation, arising from the mixture in various proportions of mineral and organic matter, from a mere clay up to the purest coal ; and it would be quite impracticable to draw any line of distinction between a " carbonaceous (or bituminous) shale " and an " earthy coal." The same person would give the different names to the same substance according to the subject or object he had in view. Moreover, the same bed of coal which is earthy, impure, or " batty ' in one place, will in another be a pure and excellent bituminous coal. By bituminous we must in all cases understand, not containing bitumen, but containing little else but the constituents of bitumen — namely, carbon and hydrogen. All kinds and varieties of coal, therefore, — cannel, caking, stone, and anthracite, — graduate insensibly into each other, not only by different beds having different qualities, but sometimes by the same bed changing gradually in its different portions. Coal, therefore, although it may be said to be organic matter mineralized, cannot be called a " simple mineral," but is a " rock," or mechanical mixture of substances in various proportions and degrees, those substances having become indurated and compacted to- gether, — partly by mere pressure, partly by the chemical action of the constituents, — just as many sedimentary rocks, containing a variety of substances — calcareous sandstones, magnesian limestones, and ferruginous shales — have become changed, or " mineralized," so to speak, not only by pressure, but by the chemical reaction on each other of their several consti- tuents. Their origin having been mechanical aggregation, their subsequent consolidation has been the result of the mechanical and chemical conditions under which they have been placed. Coal is in Britain principally confined to a certain set of rocks, called the carboniferous, occupying a posterior place in the series of stratified rocks. Wherever that set of rocks has been found in other parts of the world, it has been also found to have beds of coal. Coal, however, is by no means confined to that set of rocks, but is found in different parts of the globe in different parts of the series, from the Devonian doiyn to the most recent tertiary rocks. In all periods of the earth's geological history, wherever an accumulation of plants took place, and that accumulation was subsequently buried under beds of sand and mud, coal was the natural and apparently the inevitable result. Mineralogical characters of Coal. — The mineralogical characters of coal are very various. Anthracite appears to be almost amorphous and un- crystalline, whilst most other varieties break up into cubical or rhomboidal fragments. The fracture is either conchoidal, uneven, fibrous, or slaty ; in some cases, as in Boghead, it is conchoidal perpendicular to the plane of stratification, bvit slaty when parallel. The colour runs through all the shades, from light brown in the case of some of the Scotch cannels, to the velvet black of the caking coal of New- castle, whilst the streak following the colour passes into a brownish yellow in some specimens. Some varieties can scarcely be said to have any lustre, — as the Wemyss, Methil, and other cannels, — from which there is a gradual transition to the SPECIFIC GRAVITY OF COAL — CAEBON IN COAL. 31 shining resinous caking coals, terminating with the splendent semi-metallic and beautifully iridescent anthracites ; and every possible variety between these extremes. With reference to hardness, the anthracite variety, possessing a hardness of 2.0 to 2.5, perhaps stands at the head of the list, from which we descend through the difficultly-frangible splint of Glasgow, the sectile cannels and jet, down to the brittle, soft soiling coals of the north of England. The following table gives the range of the specific gravities of the different varieties : — America — Rhode Island anthracite . 1.7500 Ditto Pennsylvania ,, . 1.5500 Ireland — Kilkenny „ . 1.4354 ' Wales „ . 1.3750 Fiance — Canton of Lanton, near Prendle, anthracite 1.0720 England — Hetton caking 1.2740 Ditto Garesfield ,, r.2800 Nova Scotia — Picton „ 1.3250 France — Megeooste „ 1.4900 America — Madison Town caking Scotland— Glasgow splint Ameiica — Johnson's Run ditto Turkey — Silivria 1.346 to Rodosto Scotland — Wemyss cannel Ditto Boghead „ England — Incehall ,, Scotland — Rocksoles „ America — Blosshurg „ 1.5600 1.2900 1.4930 1.5300 1-1831 1.1990 1.2550 1.4480 1.7500 Coal in a Chemical point of view. — The chemical composition of coal varies even more than the mineralogical characters, but, in one respect, substances acknowledged by one party or another to be coal, differ in not yielding bitumen to any of the numerous reagents which have been employed for this purpose. Dr. Fyfe obtained the following results by acting on different coals with naphtha : — Newcastle caking Cannel coal. No. i Ditto No. 2 Ditto No. 3 . Halbeith cannel coal . Capeldrae ditto Torbane ditto fblack) Ditto ditto (brown) Per Cent, of Matter soluble in Naphtha. f4-2 5-8 [9.8 2, • 3- 4- i-S 0.0 1.2 . 1.4 The carbon varies — Erom 70.12 per cent, in anthracite from Meissner to 94.10 per cent, in that from Pembrokeshire. From 56.77 per cent, in cannel from Capeldrae to 83.75 per cent, in that from Incehall. From 74.82 per cent, in splint from Wylam to 82.92 per cent, in that from Glasgow. But the same extremes do not exist in all bituminous coals. The hydrogen varies to a much greater extent among coals generally, but not so much in coals of the same description. Thus we have 1.49 per cent, in the anthracite of the Isere deposit, and 8.86 per cent, in the cannel of Boghead. • The same remarks apply to the oxygen, no oxygen being present in some of the French anthracites, and as much as 15.51 in coal from the Dalkeith jewel seam. The most striking relation of these two elements exists in the Boghead cannel, where, with 8.86 per cent, hydrogen, there is only 3.62 per cent, oxygen ; to which circumstance Mr. Lewis Thompson very properly attributes much of the peculiar valuable properties of this coal. There is nothing very noticeable in the proportions in which the sulphur, 32 COMPOSITION OF THE ASH OF COAL. nitrogen, &c., are present, especially as the former may exist either as sulphide of iron, sulphate of lime, or in combination with the organic elements. The quantity of ash varies much more than any of the other ingredients, which is quite consistent with the origin of coal : thus in — Semi-bituminous coals we have from 2.80 to 23.69 per cent, aslie.s Bituminous do. do. 1,70 to 33.88 do. Anthracites, American do. 1.28 to 68.00 do. British coals do. 1.20 to 26.50 do. which generally consist of the same ingredients, derived from the associated stratification, as the following analyses by Kremers and Tayler, and those previously quoted by Phillips, prove : — Constituents. I 2 3 4 5 6 7 8 9 ID II Silica Alnminu Ferric Oxide . Ferrous Oxide . Lime Magnesia Potash Soda Sulphate of Lime 15.48 5.28 74.02 - 1:6 0.26 0.53 2.17 101.53 45.13 22.47 25-83 2.80 0.52 0.60 0.2B 2.37 60.23 '^% 1.08 0.35 0. [I 0.24 31.30 831 54 47 r^ 007 029 0.52 1.70 2.12 60.79 19.22 5.03 0.35 0.08 10.71 3.12 29.50 32.78 20.56 2.16 0.99 1.72 9.17 62.44 31.22 2.26 0.75 0.8s 2.48 59-56 12. ig 15.96 9-99 1. 13 1. 17 64:21 28.7B 2.27 1.34 1. 12 2.28 56.51 31.89 7.04 1 6g 0.85 1.38 0.61 58.90 26.19 5.14 5.11 0.67 1.54 2.34 100.60 98.37 98 95 '■ 'i9-i° 100.00 100.00 100.00 100.00 99-97 99.98 9- 10. II. Glance coal from Oberndorf, near Zwickau. Zwickau compact glance coal. Zwickau light soft coal. Waldenburg coal. From the coal formation at the Inde. Brown coal from Arlern. Newcastle fire-clay from between the coal seam«. Newcastle coal, after deducting 8.2 per cent, sulphuric acid. Inferior ditto, after deducting sulphui-ic acid. Shale, after deducting 39.35 per cent, organic matter. Shale, after deducting 1 1 per cent. clay. The following is the relation of silica and alumina (including ottier substances in small quantity) in the Scotch cannel coals : — Silica Alumina, &o. . 69 31 Lesmahago. 48 52 Capeldrae. S3 47 100 ' When submitted to distillation, all vai-ieties of coal, with few exceptions, yield the same solid, liquid, and gaseous products, consisting of coke, tar, ammoniacal liquor, benzene, toluene, w' Toprecxjii paqe S7. MICKOSCOPICAL CHARACTER OF COAL. 3/ tion to the antiseptic nature of the products of their decomposition. Their remains are often found forming the mineral charcoal, the mother coal or Faserkohlen of the Germans. Hatchett has noticed the same fact, and found that resin, next to woody fibre, most powerfully resisted all changes. II. Goal. — When sections of the varieties of this substance are made and reduced to a uniform degree of thinness, so that if. transparent they may be examined with transmitted light, with powers magnifying from 70 to 300 diameters, thej' will be found to present certain fixed and general features characteristic of some one of the particular class already named. The great bulk of the house' old coals, including all the coking varieties, the anthracite and steam coals, are quite opaque throughout their substance, and can only be observed by reflected light. The gas coals, such as the Pelton, the Nova Scotia, with the cannels, brown coals, jet and lignites, are all more or less transparent, and hence microscopically there are only two varieties of coaly substance — viz., the opaque and partially transparent. A transparent microscopic section of coal is seen to be composed of three very obviously distinct materials, differing in appearance and properties. (See Figs. 6, 7,8, Plate A ; and Figs, on Plate B.) These materials are — 1 . An opaque black substance. 2. A yellow or reddish substance. 3. An earthy matter sometimes more or less coloured. The relative proportions in which these substances are associated evidently influence the various products derived from them. This is very obvious when the microscopic appearance is contrasted with the chemical constitution, and more especially with the gaseous and liquid products of their distillation, and which would appear to be peculiarly dependent upon the yellow or reddish coloured substances. The black substance corresponds microscopically in appearance, and in reaction, with carbon as it is known to exist in the granular or amorphous state in various mineral substances in nature. It is insoluble in sulphuric and hydrochloric acids, and in dilute nitric acid, in caustic ammonia and potash, and chlorine is without any action on the colour. The third body named, the earthy matter, is more or less soluble in water, to which it sometimes communicates a colour, and consists chiefly of the substance known as umber. The nature of the second substance is not so easily ascertained. Its colour varies from a light yellow to a bright red or amber-coloured resinous- looking matter. It is volatilized by heat, and insoluble in oil of tar, naphtha, hydrochloric acid, and nitric acid. When free, bitumen'is present ; it colours the naphtha. It may be generally stated that the black matter forms the chief and almost exclusive constituent of household and anthracite coals, whilst the yellow matter, on the contrary, enters most abundantly into the structure of gas coal. It is also worthy of observation that the external blackness of the coal is no criterion of the presence or absence of the yellow matter, as shown by the investigation of the nature and properties of the Pelton, Nova Scotia, Boghea,d, Wigan, Eoohsoles, and similar gas coals. All the varieties of coal may therefore be classed into — I. Coal substances whose sections are for the most part opaque, and abounding in black matter of the purest kind, including the steam, coking, household, and anthracite coals. (Compare Plate B.) The coals from the low and high main seams of Newcastle Carr's steam coal, and Cowen's coking coal, may be particularly noticed as of the purest "black description, and perfectly opaque in the thinnest slices. The coal of the Button Seam, a sample from Mr. Clark, of Walker Colliery, the Ebbvale 38 VEGETABLE EEMAINS IN COAL. steam coal, the coking and anthracite coal of Pyle, Glamorganshire, and the household coal of Ehymney, belong to the same microscopic class. II. Coals more or less transparent, comprehending — 1. Gas coals with a clear shining lustre, brittle and crystalline, as Nova Scotia, Pel ton, &c. 2. Oannelsj as Peace's Wigan, Oowen's cannel, Lesmahago, &c. 3. Coal variously stratified with earthy and black opaque coaly matter, such as splint. III. Brown coals, or lignites, Bovey-coal, jet, &c. Perhaps there is no fact more strongly brought out by recent investiga- tions than the impossibility of comparing specimens of coal from the above classes with each other. Thus, for example, the common domestic coals are so black and opaque that it is impossible to make out any structure to which a reference could be made as characteristic of the class ; in Cowen's Gares- field coal no yellow matter can be distinguished, while in that from Marley Hill the texture is a homogeneous mixture of yellow and black particles ; but no transparent section can be made, and the above observation results from an examination of the powder and edge of the specimen. The only specimen of this class which presented any evidence of vegetable remains was Cowen's coking coal already mentioned. The structure seemed to present transverse sections of woody fibre. It was characterized by clear white regular spaces, with very dark bounding walls imbedded in a very dark molecular matrix, perfectly opaque. The arrangement of the presei'ved tissue was in a direc- tion oblique to the stratification of the coaly substance. The general conclu- sion is that coal, according to the class examined, has a structure peculiar to itself, but that ■ coal from the same class does not always present a uniform appearance in the mass, to the naked eye, as remains of fibres or forms of plants are sometimes found enclosed in its substance. Among the early investigators of coal, no one has paid more attention to this part of the subject than Goepert, who regards coal with a well- preserved structure as imperfectly mineralized, or not perfectly transformed into coal : a conclusion supported in some measure by Witham, and confirm- ing our remarks. This view is also adopted by Binney, who states that he has only once seen the vascular system perfectly preserved with iron pyrites in a specimen of the King coal of Wigan. The wood-like tissue seen in the coal-seams exactly resembles charcoal : it is termed " mother- " or " father-coal " by the Germans. If the coal is highly bituminous, it is so rapidly consumed that all appearance of texture is destroyed ; but specimens may be prepared for examination by the micro- scope in the following manner, as proposed by Schulz and Ehrenberg : — ■ " A piece of coal about 2 inches square is to be taken and broken into about twelve pieces of nearly the same size, and treated with nitric acid in a platinum crucible. The nitric acid is to be evaporated at a moderate heat, and the residue ignited till no further empyreumatic vapours are given ofi' : treat the residue again with nitric acid, and repeat the ignition. " Thus prepared, let the coal be placed in a platinum crucible, with a lid perforated in the centre, and blow air from a gasometer through the aperture in the lid, while the crucible is kept at a red heat over a spirit-lamp. " The object of this is that the combustion of the coal may be as slow as possible. The ash obtained ought not to cake, but should form a brownish powder. Some white splinters occur among this ash, which appear, on microscopic examination, to be aggregated siliceous cells, arranged in regular succession, and of the structure of the prosenchymatous cells of wood." As regards the ashes of the coaly substance, the observations of Lyell, Bailey, Hooker, Goepert, and others show how difficult it is to see remains VEGETABLE REMAINS IN COAL. 39 of vegetable structure in them, even when carefully prepared, and selected pieces are taken and decarbonized by the aid of nitric acid and heat. Sir C. Lyell has noticed organic structure in the coal of Eastern Virginia, which he considers to have been derived from the vegetation of the ancifent carboniferous period. Hooker examined some charcoal-like portions of this coal, and found a total absence of cellular and soalariform tissue, and thought that the structure was not referable to ferns. He found a fibrous texture, but the prominent glands were much more minute than those of coniferous wood, while the large perforated tubes were foreign to that order. The tissues consisted of parallel fibres or elongated cells, among which were very large tubes whose walls were pierced with circular or longitudinally or transversely elongated holes, either scattered or placed closely together. The microscopic tissues found preserved in the substance of coal consist of portions of vascular tissue, such as woody fibres or scalariform tissue, with cellular tissue of various kinds, — portions of the organs of reproduction, such as seeds of plants of a microscopic size, like the spores or minute seeds of ferns. Dr. Aitken was the first to detect the spores of ferns in the substance of coal, and has found them in clusters in Boghead, Capeldrae, and other coal. In Class II. the Nova Scotia and Pelton coals are both amorphous or homogeneous in their thinnest sections, but the granular black matter exists in a greater proportion in the latter. The yellow matter of the Nova Scotia coal is soluble in ether, and slightly so in turpentine and nitric acid. The solution proceeds very gradually, and leaves the black matter unchanged. The same action takes place in the Pelton coal, but much more rapidly, and a portion of its yellow matter is ^soluble in water. These features are, how- ever, more strongly developed in the cannel coals, and were first noticed by Hutton, who described them to the London Geological Society in 1832-33. The cells or spaces which he noticed and attributed to the distension produced by gas confined in a somewhat yielding material, are generally of a yellow resinous-like aspect, and may be described as areolar, while the black matter forms as it were the skeleton or network of the coal. These areolar spaces hold a definite relation to the stratification of the coal, and agree generally with what we know of stratified rocks. This is so charac- teristic of cannel and splint coals, that they may be described microscopi- cally as " stratified coals." Geological occurrence of Coal. — The greater number of coal-beds exhibit cleavages which take place in two constant directions, — one being parallel, or nearly so, to the plane of stratification, and the other perpendi- cular, thus forming an acute angle : hence the coals work or break in masses of a cubicular rhomboidal form. The distortion and flattening of the vege- table remains, and the facility with which the cleavage takes place, has generally some relation to the direction of greatest pressure. The enclosure of the yellow matter in areolar spaces bears, as might be expected, a definite arrangement in the direction of the cleavage. The spaces are flatter and broader as they lie upon the plane of horizontal cleavage, or in the direction of the line of stratification, while they are more elongated in section when examined along the edges of that plane, or along the dip of the cleavage. They vary most in sections taken " across the bed'." Messrs. Quekett and Witham describe certain appearances of coal which have led them to regard a section of cannel coal as similar to a section of wood ; but Dr. Aitken considers that these are connected with the phenomena of stratification and cleavage. The stratified appearance seen in cannel and other coals has evidently been produced subsequently to the deposit of the material from which the coal has been produced. Cracks and seams pass in definite directions through the beds of coals. When the stem of an entire tree, such as a sigillaria, is found erect, the 40 GEOLOGICAL OOCUERENCE OF COAL. Fig. I. Sandstone Shalo., Coal stratified arrangement, as seen in the bed of coal, passes continuously- through the substance of the tree when it is coalified, penetrating the stem across the position of its longitudinal fibres. This fact is of great importance in reference to the structure of coal compared with wood, for such an appearance has no similarity to a parallel arrangement of the bundles of woody fibre. Perhaps the most remarkable instance of this kind is that described by Mr. Dawson in the coal measures of Nova Scotia. In a thick bed of bituminous limestone, and in the midst of Moriday shale, is a very curious collection of upright plants. A tree, converted into coal, springs from the surface of the shale, and passes through 14 feet of sand- stone and shale. On the surface of a bed of clay, 8 feet above the main coal, stands another upright tre6, which is converted into hard shining coal, and passes through beds of sandstone and arenaceous shale to a height of 1 5 feet. Its roots, which are in a state of coal, spread in an irregular manner through the clay. He found very indistinct traces of cellular tissue in the mass, which consisted of compact coal divided by transverse joints, and an immense number of minute vertical cracks, with a few larger fissures which seemed to have a concentric arrangement. The lignites, &c., in Class III., as shown in the Bovey coal (see Figs. 2, 3, 4, and 5, Plate B), exhibit a series of gradations from the most perfect ligneous texture to a substance possessing all the characters of cannel coal ; the reverse of this is sometimes seen in splint coal, where instances of transi- tion from perfectly preserved wood to ordinary coaly structure occur. The general and microscopic appearances seen in the lignites, when compared with the cannel coals, and the whole viewed, as it were, in a series, show the actual transition of woody tissue into the coaly substance. In the three hundred specimens of bituminized woods in the German brown coal- fields, Goepert found chiefly coniferse. The preservation of this species has been explained by supposing that the deciduous-leaved trees had lost their organic connection sooner than the highly resinous wood of the coniferse, and thus become disintegrated. The changes through which the vegetable matter has passed in its conversion into coal have evidently been suspended and only imperfectly carried on in the cases of German brown coal, Bovey coal, &c. We have seen that characteristic microscopic appearances are associated with the predominance of the chemical properties peculiar to the black or carbonaceous, and the yellow, red, or volatile matter; and in the parts where tissue is preserved, as well as more particularly in the lignites, we can see that the tubes or cells have been distended unequally, and even broken up by the increase of yellow or red volatile matter, as is beautifully shown in one of Mr. Quekett's drawings. The whole range of bitumens, — pure or unmixed, mineral tars," and asphaltum, — have no structure under the microscope, being homogeneous, and clear or brown-coloured. Geologically, the brown coals or lignites are said to be of more recent formation, and in their varieties, when microscopically examined, the process of transformation is not found to have advanced so far as in cannel coal ; but no verv definite relation can be traced between the extent of the process of conversion and the geological antiquity of the species of coal. COAL BASINS. 4I In the drawings of the lignites (Plate B), the yellow material invariably occupies the spaces or cavities of cells or vessels, so that their texture becomes expanded, crushed, and broken up wherever it is found to exist. The general conclusion confirms the first statement, that coal is the product of decomposed or otherwise altered vegetable matter, associated with a variable amount of earthy substance, and capable of being used as fuel* The use of fossil fuel, which has had such a powerful influence on the history of modern times, is, even in England, a result of the scarcity of wood, and by no means very ancient. The ninth century is named by some authors as the period of the dis- covery of coal in England. In 1239 King Henry III. granted to the good men of Newcastle the privilege of digging coals, but it is not more than two hundred and fifty years since coal came into general use as a fuel in London, and at that period two ships were sufficient for carrying on the whole trade. A proclamation in the reign of Edward I., and another in the time of Elizabeth, prohibited the use of stone coal in London during the sitting of Parliament, lest the health of the knights of the shire should suffer during their residence in the metropolis; and shortly before 1649, the citizens of London are stated to have petitioned Parliament against two nuisances or offensive commodities which were likely to come into great use and esteem, and these were, " Newcastle coals, on account of their stench, &c., and hops, in regard they would spoyle the taste of drinck, and endanger the people." Newcastle coal was first introduced in Paris in 1 5 2 o. In the west of Scot- land, the privilege of digging coal was granted to a religious house in 1291, but as early as a.d. 1200 collieries were' being worked on the south shore of the Firth of Forth.f In Belgium, the earliest reference to mineral coal was in 1 198 or 1 200 in the county of Liege, where tradition ascribes its application as a fuel to a blacksmith.J According to Marco Polo, the Chinese were acquainted with coal as a fuel at a very early period. § Coal is very much more abundant in the carboniferous and secondary, than in the tertiary formations ; the deposits in the two former being, indi- vidually, much more extensive. It occurs in beds, or seams, sometimes called veins, interstratified with numerous other minerals, filling up what appear to have been hollows, or valleys, at the time of its deposition, and have frequently received the appellation of coal basins. The separate layers of coal and other minerals generally come to the surface, or crop out at the sides of these basins, defining thus the entire outward area of the formation. Fig. 2. The accompanying cut, Fig. 2, represents one of the basins belonging to the * For further information upon the microscopic structure of coal, we mny refer to the works and monographs of Deoandolle, Brongniart, Ijindley, Button, Hooker, Binney, Karsten, Nicol, Witham, Goepert, Oorda, Teschmacher, Bennett, Quekett, Eedfem, Greville, Balfour, and Fleming. t See " Records of Early Mining in Scotland," by E. W. Cochran-Patrick, LL.D. (Edinburgh, 1878) ; and also " History of Coal Mining," by E. L. Galloway (London : Macmillan). t "History of Fossil Fuel." § " In the Mountains of Cataja,'' as this distinguished traveller relates, " a kind of black stone is dug up, which laid upon the fire bums like wood, and when once ignited continues to bum for a long time, so that, if placed upon the fire in the evening, it will burn during the whole night. The stone when first ignited produces a small flame, like charcoal ; it then continues to glow and gives off much heat." 42 FAULTS IN COAL BEDS. Somersetshire and South Gloucestershire coal-fields. The elevations at A and B represent the old red sandstone formations of the Mendip Hills and Wick Rocks, the strong black lines the coal measures, and the others the rock with which they alternate — the lowest being mountain limestone ; the next, millstone grit ; whilst the dotted portion is Pennant grit rock, through which runs the river Avon, as indicated by the indentation at 0. Above the higher beds of coal, the first horizontal stratum E consists of new red sandstone, upon which repose beds of lias F ; the middle portion here, underlying the bifurcate section of Dundry Hill B, consisting of oolite; both these last-named are species of limestone, containing vast quantities of marine shells. The Valfe of Clyde, in the county of Lanark, the most valuable Scotch coal-field, is a vast basin, or trough, the strata composing which crop out at the surface, at variable distances, on both sides of the river. The South Wales coal-field, comprising an area of upwards of 900 miles, was supposed at one time to form a perfect basin, in the shape of a long-necked fiask ; but it has since been shown to be rather what is termed an inverted basin, the section, Fig. 3, presenting a rising of the measures on each side of the anticlinal axis A. The basin-shape appears to have been the original one in all the coal- fields ; but, in many instances, this has been subsequently modified by FiG. 3. powerful subterranean disturbances, producing slips, dykes, and dislocations. Thesefatdts, as they are sometimes called, consist of fissures, varying from a fraction of an inch to several yards in width, extending often for several miles, and to an undefined depth ; on either side of them the strata have altered their relative positions, the rock having not only been rent asunder, but raised on the one side of the. fissure, and depressed on the- other, although it is impossible to ascertain on which side the elevation, depression, or rather the absolute motion, has occurred. The subjoined section, Fig. 4, Fig. 4. illustrates the manner in which the strata of the coal measures are dis- located, by faults in the neighbourhood of Jarrow, near Newcastle. Thus the same strata are found at different levels on opposite sides of these faults ; the difference of level varying from a few inches to 500 feet, and in some in- stances to even 1,200 feet. The fissures are usually filled with clay, containing FAULTS IN COAL BEDS. 43 fragments of the contiguous strata. Sometimes, however, basalt and other volcanic rocks appear to have entered them in a melted state from below, changing the nature of all the strata on which they impinge, and, of course, converting the coal, more or less, into coke. Fio. 5. The diagram. Fig. 5, exhibits a section of the great slip of the North- umberland and Durham coal-field, known as the great, or ninety- fathom dyke (A A), in consequence of the beds on the northern side being 90 fathoms lower than those on the southern side of it. The section is from a portion of a coal-field near Newcastle. This dyke is in some places 22 yards wide, and is filled with hard and soft sandstone. It is intersected by several other dykes, one of which is 70 yards wide, and by the whin dyke B BB, the central portion of which consists of basalt, 16 feet in thickness, and extends in an undulating course, underground, to a distance of about 11 miles. C C shows the high main coal ; D D, the low main coal ; E E, the Beaumont seam ; F F F, level of the river Tyne; H, Benwell colliery; K, Newcastle town Moor. A coal-basin always comprises a series of deposits of coal varying from two to sixty in number, and from a fraction of an inch to several feet in thickness ; these are separated from each other by numerous strata, consisting chiefly of different varieties of sandstone, clay, and shale. Thus, in sinking a shaft at the Gosforth Colliery, about two miles north of Newcastle, the number of strata sunk through \vas as many as 142, the total depth being upwards of 188 fathoms. Forty-three seams of coal were pierced ; many of them, however, were very thin, and incapable of being worked with profit. Much coal is worked about Newcastle at a depth of 400 feet, and it is generally oKserved that the thickness of the seam increases with the depth from the surface. The sandstone rock which covers the coal in the above locality is so massive that in some cases wooden supports are unnecessary in the workings. In the South Stafibrdshire coal-field, the main coal is about 6og fathoms below the surface in the neighbourhood of Dudley, and is 10 yards in thickness; below it is another bed, 5 yards thick. At Gittersee, in the Valley of Plauen, near Dresden, there are seven beds, between which six thin layers of soft clay intervene. Although it does not come within the province of this work to enter into details concerning the distribution or statistics of coal, yet the following general summary, taken from Mr. R. C. Taylor's " Statistics of Coal," may not be found uninteresting. The geographical distribution of coal in Europe and America is very unequal in the different countries. The follow- ing table shows the relative magnitude (1855) of the principal coal-producing countries, and respective areas of coal land, together with the proportions which they severally bear to each other. Those of France and Spain are considerably less than the actual amount ; and Prussia, which is not included in the table, produces nearl}' as much coal as France. 44 AREA OF COAL BEDS. Proportion 01 coal Relative Entire area Area of amounts of Countries. of each coal land. land to the coal area country. whole area. per 1,000. S(]uare miles, Square English. miles. Great Britain ar.d Ireland 120,290 11.859 I — 10 64 Spain (Asturias region) .... 177,781 3.408 1-52 18 France (area of fixed concessious) in 1845 . 203,736 1.719 I— 118 9 Belgium, conceded lands .... 11.372 ' 518 I — 22 3 Pennsylvania, United States . _ . 43.960 15.437 1—3 84 British Provinces : New Brunswick, Nova Scotia, Cape Breton, and Newfoundland . 81,113 18,000 1-44 98 United States of America .... 2,280,000 — I— 17 The twelve principal coal-producing States 565,283 133.132 1—4 724 184,073 1,000 Great Britain and Ireland, therefore, abound most in coal amongst European countries, whilst Belgium, as regards territorial proportion, comes second, although in relative coal area she is the least of the four. Pennsylvania possesses more coal land in proportion to its extent than any other country, although it is exceeded in actual quantity by the British provinces of North America. The area of coal in the United States is nearly three-fourths of the whole amount in the table. The following diagram, perhaps, conveys at once a more accurate im- pression of the I'elative coal areas of the principal coal-producing countries, than the foregoing table ; it is also borrowed from Mr. Taylor's work. These Fig. 5a. diagram of the superficial coal areas of various countries. tales or America JSituminous Coal^rea 133jl33 sq.Tniles. ?2! p art of the whole , 124,735 sq. miles east of the Mississippi river, 8,397 sq. miles west of the Missouri river. Anthracite Pennsylvania, i5»437 si- miles, i/srd. Eritish America hituminous cua!, 18,000 sq. miles, 2/gths. France, Great Britain and i,7ip Ireland, 3,720 sq, sq. miles, miles, anthracite i/ii8th. and culm. Spain, 3.408 sq, miles. i/52nd. Belgium, sq. miles, i/22nd. i/ioth of whole area. tables, showing ihe relative areas of the coal districts in different countries, can- not be taken exactly as an index to the quantities of coal capable of being raised in the. respective localities ; as the number of seams of coal, their thickness, the ease with which they can be worked, their proximity to economical means of transport, and numerous other circum.stances, must all influence, more or less, the productiveness of the mines, and the relative values of the produce. The following table exhibits the relative annual production, value of the coal, anthracite and lignite, in the six great coal-producing ANNUAL PEODUCTION OF COAL. 45 countries of the globe, in the year 1845, from which time up to the present a regular increase has been simultaneously going on in all : — Square miles Tons of fuel Relative Officia: estimated Countries. of coal raised in parts of value at the places formation. 1845. 1.000. of production. Great Britain .... 11,859 31,500,000 642 9,450,000 Belgium 518 4,960,077 lOI 1,660,000 United States 133.132 4,400,000 89 1,373,963 France ... 1. 719 4,141,617 84 1,603,106 Prussian States Not defined 3,500,000 70 856,370 Austrian States Total .... ,, 659,340 49,161,034 14 165,290 1,000 15,108,729 The total quantities of coal raised in Great Britain in the years subsequent to 1840 were as follows : — 124,937,925 tons 131,867,916 ,, • 133.470,478 „ 134,610,763 „ . 146,818,122 ,, 154,184,300 „ 156,499,977 „ '63,737,000 „ 160,757,000 „ 159,333,000 „ The number of miners employed was, in 1881, 501,000 ; and the value of the fuel raised, about ;^5o,ooo,ooo. The total annual produce of the world is certainly not less than 300,000,000 tons. According to Pechar, about 1 1 per cent, of the total British production is exported, the general distribution of the coal being somewhat as follows : — 1840 34,026,108 tons 1874 1845 . 31,500,000' „ 1875 1850 44,612,271 „ 1876 1855 64,453,079 „ 1877 i860 80,042,698 „ 1880 1865 98,150,587 „ 1881 1870 109,035,284 „ 1882 I87I 117,352.028 „ 1883 1872 123,492,050 „ 1884 1873 • 127,016,747 „ 1885 Destination. Iron manufacture Factories Dwelling-houses . Gas and water works Mining Steamers Railways Copper works Sundries Export Per cent. 32.40 21.87 16.36 6.46 6.38 6.46 1.76 0.72 0.64 10.54 The numerous varieties of mineral coal have given rise to distinc- tions which are based partly on age, partly on appearance, and partly on quality. In most kinds of coal, the structure of the wood from which they have been formed is entirely obliterated ; partial impressions of single parts of the plants alone indicate their origin. They form a compact deep-brown or perfectly black mass, sometimes dull, but generally having a fatty or vitreous lustre, and often exhibiting a play of colours ; they present a finely granular fracture, not at all fibrous, and are much heavier than wood, bulk for bulk; they occur more or less stratified, and are nearly always fissured at right angles to the plane of stratification, in a manner similar to that which is observed when a doughy mass becomes dry. These fissures are often narrow, and first appear distinctly when the coals are broken up ; but not unfrequently they are found open or filled with mineral substances, as iron 46 VARIETIES OF COAL. pyrites, calcareous spar, galena, dolomite, heavy spar, gypsum, clay, the soda- salts, and by a double carbonate of lime and iron. Independently of the want of connection in the coal mass, the causes of which have been referred to, the hardness and solidity of the coal are not very great. The fracture of the shining kinds of coal is- conchoidal ; of the other kinds it is even or hackly. Common coal, particularly that from more recent formations, is frequently aocompaaied by a small quantity of a kind of coal which can at once be distinguished from the great bulk by its colour and structure, and still more perceptibly by the difficulty with which it burns ; it often appears in thin layers parallel with the plane of stratification, or is disseminated throughout the whole mass of the vein. This variety is often cal\ed fibrous or fibre-coal ; it is richer in carbon, and consists of coal somewhat more advanced in the process of alteration than the other and larger portion, affording a striking exemplification of the change which is going on in all coal. The entire substance of coal, particularly that of the younger de- posits, is observed to be made up of portions rich in carbon, along with others which are comparatively poor ; it is a mixture, therefore, of coal in two stages of decomposition, of which the one is black, of a pitchy lustre and conchoidal fracture, the other dull, brown, and even. It might be thought, perhaps, that an unequal facility of decomposition in the different parts of the plants from which the coal is derived is the cause of this ; but such a supposition is dis- countenanced by both stages occurring stratified, and in all manner of relations towards each other, from thin veins frequently alternating, to veins of several inches in thickness, fragments of these appearing to be homogeneous. The varieties of pit coal, excluding the anthracites, are so very numerous, and pass so imperceptibly the one into the other, that many specimens can with difficulty be classified under any general denomination, or sub-species. The most marked physical varieties are those generally known in this country as caking coal; splint, or hard coal; cherry, or soft coal; and cannel, or parrot coal. Caking Coal is velvet-black, or greyish-black, of a shining resinous lustre, and a small-grained or uneven fracture ; when heated, it fuses together into a pasty cake, from which the bubbles of volatile matter escape as from a dough, leaving a coke of a totally different shape to the original coal. It soils the fingers, and breaks up into more or less cubical fragments ; when ignited, it burns with a lively yellow flame, but requires frequent stirring in consequence of its caking property. It is inapplicable in many furnace operations in consequence of this peculiarity, and requires, when used for such purposes, to be previously converted into coke. Its composition will be seen from the tables in the following pages. The principal beds in the Newcastle coal-field are composed of this variety, as is also the sixth bed — reckoning from the surface — in the Glasgow coal-field; it is also abundant in other localities. Splint, or Hard Coal, is black, with a shade of brown; it has a glistening resinous lustre, inferior to that of the cherry coal ; the principal fracture is imperfect, curve slaty ; the cross fracture is fine-grained, uneven, and splintery ; it is not easily broken, hence one of its denominations. It is kindled with greater difficulty than either caking or cherry coal; but affords a lasting and clear fire, giving out much heat. This coal is very abundant amongst the Glasgow beds, and is the most highly prized. Cherry, or Soft Coal. — This most abundant and beautiful variety is velvet-black in colour, with a slight intermixture of grey; it has a re- splendent, or shining resinous lustre, whence it has derived its name of cherry from the miners. It does not cake when heated. The principal fracture is straight, slaty ; different slates varying much in lustre. It is ANALYSES OF CANNEL COAL. 47 very easily broken, and there is consequently mucli waste in mining it. It readily catches fire, but burns away much faster than other varieties. The greater part of the uppermost bed of the Glasgow coal-field and the Staffordshire coal belong to this species. Cannel, or Parrot Coal. — Called cannel from its property of burning with a clear flame, like a candle, and parrot (in Scotland) from its property of flying off with a loud crackling sound when flat fragments are placed upon the top of a fire. This coal has a dark greyish-black or brownish colour, the lustre is glistening resinous, it takes a good polish, and can be made into inkstands, snuff-boxes, beads, and other ornaments; the fracture is flat conchoidal, frequently slaty. It does not soil the fingers, and does not break easily. It abounds at Lesmahagow near Glasgow, Wigan in Lanca- shire, and near Coventry in this country. Jet is only a variety of cannel coal. The following tables give the composition of nearly all the varieties of cannel coal known in Great Britain, and of some other varieties which are used in the manufacture of gas : — Sulphur in Name of Coal. Specific Gravity. Volatile Matter. Coke. Ash. Coke. Per Cent. Coal. Coke. Volatile i Matter. Lochgelly Cannel 1.320 33-5 66.5 13.1 29-7 0.75 0.25 °-5 New' Brunswick Cannel (&s- phaltum) J.098 66.3 33-7 0.6 1.78 0.7 — 0.7 Pelton Main - 1.270 28.4 71.6 1.41 1.96 i.i 0.62 0.48 „ Cannel . 1.320 31-5 68.5 9-4 13-7 0.95 0.49 0.46 Leverson's WaUsend . 1.278 34-9 65.1 4.9 7-52 1.3 0.65 0.65 ,, „ Cannel 1.320 30.8 69.2 9- 35 1.3.67 1.0 O.S 0.5 Washington 1.260 31-25 68.75 2.2 3.2 1-3 0.67 0.63 ,, Cannel 1.326 27.4 72.6 9-37 12.9 1.1 0.56 o.SS Eelaw Main . 1.271 30.3 69-7 2.60 3-7 1.2 0.7 0.5 Uipeth 1.271 28.7 71-3 '•35 1.89 1.0 0.6 0.4 New Pelton 1.265 30.2 69.8 1.71 2.5 1.1 0.56 0.54 Dean's Primrose 1.261 29.25 70.75 2.4 3-4 1.4 0.71 0.69 StaTeley (Derbyshire) 1.27s 40.9 59.1 2.7 4-57 1.2 0.8 0.4 Elseear Low Pit (Vorkshire) 1.258 37-0 63.0 1.1 1-74 1.2 0.63 O.S7 Griglcston Cliff, soft „ 1.25s 35-6 64.4 1.6 2.48 1-4 0.75 0.65 Silkstone, No. i „ 1.26 34-1 65.9 2.78 4-2 1.3 0.8 0.5 No. 2 1.259 38-0 62.0 2-55 4.1 1.1 0.6 0.5 No. 3 1.262 35-2 64.8 2-8 4.3 1.45 0.75 0.7 Arley (Lancashire) . 1.270 33-7 66.3 3-6 4.8 ■ 1.2 0.6 0.6 Heathem (Staffordshire) . 1.280 42.9 57-1 '•75 3-0 1-5 0.7 0.8 Coalpit Heath (Gloncestershire) 1.370 30.1 69.9 5-8 8.3 4.1 2.2 1.9 Radstock (Somersetshire) . 1.275 38.25 61.7s 3-5 5-6 3.1 1.8 1-3 Ehondda (^. Wales) . 1.278 22.8 77.2 2.7 3-5 2.3 1.2 1.1 Denain (Valenciennes. France) . 1.265 23.9 70.1 6.0 3-5 2-4 1.3 1.1 West Hartley . 1.269 35-8 64.2 4.7 7-3 1.1 0.6 o-S Hastings Hartley 1.278 36.5 63.4 2.0 3-1 0.95 0.5 0.45 Gosforth . 1.260 35.0 65.0 I.O 1-5 i.i 0.5 0.6 South Peareth . 1.266 27.8 . 72.2 1.8 2-5 1.2 0.6 0.6 Garesfield (Bute's) . 1.290 28.3 71.7 3.2 4.4 0.9 0.4 0.5 „ (Cowan's) 1.259 29.4 70.0 0-95 1.3 0.85 0.4 0.45 South Tjne 1-339 36.3 63-7 3-9 6.1 2.1 1.1 1.0 Blcnkinsopp 1.298 38.0 62.0 S-i 8.2 1.6 0.8 0.8 Woodthorpe (S. Yorkshire) 1-347 3.3.1 66.9 10.5 16.6 1.2 0.7 0.5 Soap House Ht „ 1.258 35-0 65.0 0.8 1.2 0.7s 0.4 0.35 Mortomly „ 1.220 37-0 63.0 1.6 2.5 I.I 0.6 0.5 Cumberland, No. z 1.294 2S-5 74-5 2.1 2.8 1-3 0.7 0.6 No. 2 . 1.275 25.6 74-4 1.4 J-9 1.1 0.6 o-S No. 3 . 1.290 30.9 69.1 4.0 5.8 '•7 0.8 0.9 Bnabon, Nant Seam (N. Wales) . 1.269 37-9 62.1 1.4 2.2 1.1 0.7 0.4 „ Top Yard Seam „ 1.269 37-5 62.5 2-5 4.0 1-4 0.8 0.6 „ Main Coal „ . 1.284 41-5 58.5 1.0 1-7 0.85 0.45 0.4 Yard Seam „ 1.271 34-0 66.0 1-4 2.1 1.1 0.6 0.5 Bhondda Low Main (S. Wales) . 1.280 23-1 76.9 2.1 2-7 2.2 I.I 1.1 Nailsea (Somersetshire) . 1.312 34-9 65.1 3-0 4-6 2.8s 1.5 1-35 Silverdale. lo feet (N. Stafford). Woodshutts, 7 feet, Banbury (N. 1.301 34- 66.0 1.95 2.92 1-3 0.7 0.6 Stafford) .... Apedale (N. Stafford) 1.291 40.2 59-8 1.22 2.03 0.9 °-S4 0.36 1.307 38.5 61.S 1-9 3-1 1-5 0.82 0.68 „ 4 feet „ 1.267 40.0 60.0 0.75 1. 25 0.80 0.38 0.42 Harecastle (Cheshire) 1.230 31-5 68.S 5.0 7-3 2.1 1.1 I'.o St. Helens (S. Lancashire) 1.285 37-2 62.8 1.2 1.91 1.1 0.54 0.56 Staffordshire Cannel . 1.220 50.0 50.0 2.9 5.8 1.3 0.52 0.78 Whitecrolt, near Lydney (Glou- cestershire) . 1,401 34.3 65.7 11. 1 16.8 31 1-9 1.2 48 ANALYSES OF CANNEL COAL. Cannel or Parrot Coals. Coal. Coke; Specific Volatile Matters. Fixed Carbon. Per Cent. Ash. Per Sul- phur. Per Cent. Watsr. Per Total Amount of Coke Carbon in Coke. Ash in Coke. Per Cent. Per Cent. Cent. Cent. in Coal. Per Cent. Per Cent. Roehsoles . 1.448 53-7 4.9 38.8 1.6 I. 42.3 11-58 88.42 Hirdie's 1.420 34. 4. 58.4 ^ 3-5 62.4 6-44 93.56 Boghead, Brown . 1. 160 71.06 7.10 26.2 .24 •4 28.3 ^5-°9 74.91 Black . 1.2185 62.7 9.25 26., •35 1.2 35.7s 25-88 74.12 Torbanehlll . I. 1892 67.11 10.52 21. ■32 i.os 31.52 33-38 66.62 Boshead 1. 1550 7I.3 11.3 16.8 •34 .6 28.1 40.22 59-78 Bathville . 1. 201 64.3s 12.6 22.2 .25 .60 34.80 36.21 tl^'H Stan (Ayrshire) . 1.4647 52.08 14.77 32. 1.15 46.77 31.52 68.48 Metliill 1.3002 49.23 17.57 29.7 — 3.50 47.27 37.17 62.83 Capeldrae . 1.3603 45.73 19.97 31.5 — 2.80 51-47 38.80 61.20 Wemyas 1.1831 58.52 25.28 14.25 — 1-95 39.53 63.9s 36. 05 Balhardie 1.420 38.96 29.66 28. .38 3-° 57.66 48.56 51.44 Hillhead (Kilmar- ) nock) . t 1.602 1 36.65 32.34 27.4 .61 3- 59.74 54.14 45.86 Brymbo 32.10 36.4 29.4 — 2.1 65.80 S5.32 44.68 Lesmahagow (&uchin- heath) 1. 1990 56.23 36.7 4.3 .55 3.15 41. 89.50 10.50 Bartoushill . 1.280 48. 39.6 10. 2. 2.4 49.6 79.84 20.16 „ ... 1.350 38. 37.9 18.7 2.2 3.2 56.6 66.96 33.04 Stevenston (Ayrshire) . 1.385 40.21 40.14 19.35 ■3 59.49 67.64 32.36 Lesmahagow (South- field) . 1.228 49.34 40.97 6.34 1.35 2. 47.31 86.60 13.40 Enightswood 1.234 44.77 4' 13 11.05 3.05 52.18 78.83 21.17 Gaimbroe 1.247 42.83 42.67 8.50 51.17 83.39 26.61 Skaterigg . 1.252 49.32 44.83 3.50 3.35 47.33 94.42 5.58 Cowdenhill . 1.299 40.0 45. 5. .50 3.50 50. 90. 10. Bredisholme 1-335 39- 48.5 8.1 .4 4. 56.6 85.69 14.31 Eiiehill 1.223 45.73 49.27 2.5 2.5 51-77 95.17 4-83 Kelvinside . 1.231 40.17 53.42 1.9 .21 4.3 55-32 96.57 3-43 TABLE SHOWING NATURE OF THiE ASH OF CANNEL COALS AND SHALES. Locality. Specific . Gravity. Volatile Matter. Fixed Carbon. Ash. Composition of Ash. Kirkness . 1.208 60. 40. 13.5 Silicate of alumina and oxide of Old Wemysa 1.325 52.5 47.S 15 I Ditto. Enightswood 48.5 51-S 2.4 Oxide of iron and silicate of lime with alumina. Armiston . 1. 196 45.5 54-5 4.18 Ditto. Wigan . ... 1. 271 37-0 63.0 3-° Oxide of iron and silicate of alu- mina. Ramsey's Newcastle . 1.290 36.8 63.2 6.6 Oxide of iron and silicate of lime . with alumina. Boghead Coal (Mean of 3 ex- 1 pcrlments) . . . f 1.209 69.70 7.73 22-57 f Silica 69 °/o. Alumina, oxide of 1 iron,lime,magnesia,&o., 31% Lesmahagow Parrot Coal, Mean 1.230 51.44 39.57 898 Silica 48 °/o. Alumina, &c., 52 %. Capeldrae 1.321 50.00 33.90 16.10 „ 53% „ 47%. Balhardie 1-443 52.05 21.28 26.67 „ 70 7o ,. 3°%- MethUl 1.147 69.43 21.84 8.72 fiochsoles „ „ . . 1.161 70.59 13.14 16.27 Fife „ „ No. 1 1.430 45.50 32.5s 21.9s „ No. 2 1.327 46.56 39-55 13.89 Cherry Coal from Torbanehill Parrot — 42.16 40.90 16.94 Silica 65 7o. Alnmina 35 "/„■ Porbanehill, top of House Coal . 1.327 32.27 64.80 2.92 „ bottom „ 1.401 28.11 42.22 27.28 Silica 78 %. Alumina 22 7o. Shale from Stirlingshire Coal- field .... 2.344 16.53 — 83.47 Silica 78 7o. Alumina 22 %. Birtledean Shale, Lancashire . 2.390 16.84 — 83.16 „ 82 7o. „ 18 %• Pendleton ,, ,, 2.642 22.52 — 77.47 Fife " Rums " . . . . 1.694 26.74 20.51 52.75 The foregoing analyses show that cannel coals yield, on distillation, a very much larger amount of volatile matter, less coke, a larger quantity of ash, and generally more sulphur than the so-called bituminous class. ASH IN COAL. 49 Anthracite is not compared in these tables on account of its yielding little or no volatile matter. The ash of the cannels will be found to consist chiefly of silicate of alumina, and has been observed to bear a remarkable analogy to decomposed felspar from which a portion of silicate of potash has been washed out. This, when considered in connection with the large relative amount of ash in cannels, has suggested the inference that these varieties have been formed by the decomposition of an accumulation of the lower order of vegetables, such as mosses, lichens, sea-weed, &c., deposited with the debris of the oldei' rocks, whilst the occurrence of ammonic chloride, and occasionally of compounds of iodine as observed by M. Bussy in the coal and products of distillation, points to a marine origin of the vegetable remains, or to a submergence below the waters of the sea. The ash of bituminous coal, on the other hand, consists generally of calcic siheate and sulphate with oxide of iron and some argillaceous matter, the greater portion of which may have formed the natural ash of the large trees to which the formation owes its origin, and which are known to belong to a class [Equisetacece) yielding a silicious ash. Sulphur is, with some marked exceptions, generally found in larger quantity in the cannels than in the bituminous coals, and a larger portion passes off with the volatile ingredients on distillation, partly in the form of sulphuretted hydrogen, but more as bisulphide of carbon. This fact has led to the conclusion that the sulphur in cannel coal is not derived exclusively from iron pyrites, as in bituminous coal, but exists in some other form of combination, from which it is evolved at a lower temperature, and is thus enabled to enter more readily into combination with carbon. Bituminous coal is never entirely free from iron pyrites or ferrous sulphide, and this, in presence of water and a high temperature, is decomposed, forming, with the elements of water, ferric oxide and sulphuretted hydrogen. Calcic carbonate frequently accompanies the layers of coal, forming thin bands between the seams ; and at a high temperature, in a retort, this is decomposed, the carbonic acid being driven off and the calcium entering into combination with the sulphur, which it fixes so that a less quantity of sulphur escapes in the form of gas. Cannel coal is superior to all other kinds in the propor- tion of volatile matter which it yields. In the trade, a great variety of appellations for coal are current, derived chiefly from the names of the pits where they are mined. These may afford some clue to the values of the coals amongst dealers and persons conversant with the trade, but are of no service to purchasers without some previous knowledge of the characters as deduced from experiment. Compact masses of common coal of a pitchy lustre are called by some mineralogists pitch coal; more distinctly stratified kinds, splitting in a horizontal direction, slate coal ; such, as falls into very thin layers, leaf coal ; and that which is dull and more massive, coarse coal, &c. The classification of coal according to the properties it exhibits when submitted to dry distil- lation will be noticed in describing the process of coking. The specific gravity of bituminous coal varies from 1.2 to 1.5. Coal fresh from the pit, when exposed to the air, loses a portion of moisture without parting with the whole, retaining, according to its nature, from i to 12 per cent. ; artificially dried coal re-absorbs hygroscopic moisture from the atmosphere. Ash in Coal. — On an average, coal leaves less ash* than brown coal or turf, but, in consequence of the substances contained in its fissures, more than wood. On this point and the specific gravity of coal, the necessary information is contained in the fbllowing table ; — * See " Trans. Newcastle Chem. Soc," vol. Iv. pp. 135 and 140. E 5° SPECIFIC GRAVITY OF COAL AND ASH IN GOAL. Description and Locality cf Coal, Splint Cannel Cherry Caking f Wylam Banks, Newcastle 1 GluBgow coal-field . j Wigan, in lyancashire t Parrot coal, Edinburgh . I Jarrow, Newcastle . 1 Chief mass of coal from Glasgow j Garesfield, Newcastle t Sonth Hetton, Durham . Alaisi Eochebelie . f fat and hard Rive deGier (P. Henry) \ coal Flenii from Mons Coal Second- ary for- mation Cimetiere, Eive de Gier Couzon „ fat coal, \ producing a long flame Epinac Commentry Blanzy . . (dry coal, long flame) Rive de Gier, Grand Croix ( fat and ) .. , t^hard I Anthracite, Lamure, Dep. de I'lsere ,, Macot .... Common coal, Obemkirchen, Lippe-Sch, Cdral, Dep. Aveyron Noroy, Vogesen St. Girons .... Belestet Czeniitz, Upper Silesia . Gnatle Gottes, Lower Silesia . Glilcklralf ,, Sulzbacb, Duttweiler, Saarbriicken Wettin, Saalkreis . Salzer and Neuack, Westphalia Pottschappel, Saxony Konigin Louise, Upper Silesia Konigsgrube, . „ Merchweiler, Saarbriicken Frischauf, Lower Silesia Hundsnaker, Westphalia Beata, Upper Silesia Brazils .... Coarse coal, mixed with Pitch coal Slate coal, „ „ „ with Fibre coal Anthracite .... Slate coal, with a little Fibre coal Hard Slate coal, with layers of Pitch coal Slate coal, with predominating layers of Anthracite and Fibre coal . Specific Gravity. 1.302 1-307 J-3I9 1.318 1.266 1.286 1.280 1.274 1.322 i-3'S 1.276 1.292 1.288 1.294 1.298 1. 3" 1.284 ••353 1-319 1.362 1.298 1.302 1.362 1.919 1.279 1.294 1. 410 1.316 1-305 1-362 1.285 1.276 1.258 1.466 1.288 1-454 1.280 1.285 1.282 1.518 1-338 1-383 1.483 1.48 1.24 1.20 1-37 1-25 1.42 '-35 Ash in 100 parts. Observers. 13-912 1.128 2-545 14.566 1.676 1. 421 1-393 1-519 1.41 2.96 2.10 3-68 3-57 2-99 2.72 5-32 5-13 2-53 0.24 2.28 1.78 1-44 4-57 26.47 1.0 11.86 19.20 4.08 0.89 5.80 4-65 0.8 0.15 24.4 0.7 27.7 1.2 0.6 0.9 23-4 0.6 11.9 28.4 20.9 22.7 26.3 22.5 20.2 24.0 23-4 Richardson / RegnauU ) Karsten \ Lampadius The mean specific gravity, therefore, of a coal with 8.73 per cent, of ash would appear to be = 1.33. If, however, those varieties containing an excessive amount between 19.20 and 28.4 per cent, of ash are not included in the calculation, a mean specific gravity of 1.30 will be obtained for coal containing on an average 5 per cent, of ash. ' From the foregoing table, no direct connection between the specific gravity and the amount of ash contained in any speciinen of coal can be deduced, although Professor Johnson believed that such was the case with coal from the same field, and considered the specific gravity as an index of the purity of coal. In analysing anthracites' from Beaver Creek, Luzerne Co., he found in four varieties the following relative quantities of ash : — ASH IN COAL. 51 Sp. gr. Ashes per cent. 1. 1.560 . 1.28 2. 1-594 . . 4.00 3. I.613 . ... 5.01 4. 1630 . . . . 5.063 In the coal from the basin of Maryland bordering on Pennsylvania, a similar result was observed : — Me&n specific gravity Mean percentage cf earthy matters of two specimens. in the two specimens. 132 ■■3| 1-365 1.385 1.485 7-52 9.58 IO-3S "•75 14.41 From these results, it would seem that the specific gravity does increase in some cases with the amount of ash ; but, as will be seen by the tables in subsequent pages, it is by no means a general fact. The quantity of ash aiforded by coal in a laboratory experiment frequently varies very considerably from that obtained from furnaces in actual work. Thus, it was found, by the experiments undertaken for the Admiralty Coal Investigation,* that the average amount of ash yielded in the laboratory from thirty specimens was ...... 5.76 per cent. while the average afforded from the residues of the furnace was only ......... 4.62 „ leaving a difference, therefore, of . . . . . 1.14 „ or a less quantity by ^ than by the laboratory operations. The explanation of this difference is due to the greater heat of the furnace leading to the volatilisation of alkali in the draught, and probably also to the dissipation of some of the ash by the strong current passing through the furnace. In a few instances in this series of experiments, the reverse was observed to be the case ; and in a large series of experiments undertaken by Johnson on American coal the reverse was also observed. Here the average amount of ash obtained by laboratory manipulation was . . 7.76 per cent, that obtained from the residues of the furnace . . 9.10 „ showing a difference of ....... 1.34 „ in excess, or 17.27 per cent, more ash in the furnace than in the laboratory. It is obvious here that some of the carbon must have received a silicate glaze owing to a too rapid elevation of temperature in the furnace ; in this way it would count as ash. The greater proportion of ash contained in the American coal as compared with the British is probably due, in great measure, to the care which was taken to select the latter free from slaty matters, it having been usually mined expressly for the investigation ; and these substances will find their way into commercial coals, when special care is not taken to prevent it. The amount of ash in several varieties of British coal will be found in the following tables showing the composition of coal. The physical character of the ash of coal generally resembles that of brown coal ; but its chemical composition depends much on local circum- stances. In many varieties of coal-ash, silica and alumina predominate ; in others, gypsum and oxide of iron due to pyrites, the latter being a highly injurious ingredient for most applications of the coal ; besides these, the ashes contain oxide of iron, oxide of manganese, lime and magnesia in combination with carbonic acid, sometimes traces of lead and copper, phosphoric and * Vide Tables at pages 53-56. E 2 52 ASH IN COAL. sulphuric acids, with small quantities of chlorine and iodine, although, rather strange to say, no alkali. The ashes of seven varieties of bituminous coal have been analysed by Mr. J. A. Phillips, for the Admiralty Coal Investigation, with the following results : — Alumina Mair- Sul- Phos- Total Percentage Percentage Name of Coal. Silica. and Oxide Lime. phuric phoric per- of Ab>h in of Coke in of Iron. Acid. Acid. centage. Coal. Coal. Pontjpool 40.00 44.78 12.00 trace 2.22 0.75 99-75 5-52 64.8 A Bedwas . 26.87 56.95 S-io 1.19 7.23 0.74 98.08 6-94 71.7 « ■ Porthmawr 34-21 52.00 6.199 0.659 4.12 6.633 97.S21 2.91 63.1 ^ EbbwVale 53.00 35.01 3-94 2.20 4.8Q 0.88 99.92 14.72 77-5 Coleshill . 59=7 29.09 6.02 1-35 3.84 0.40 99-97 10.70 — ■s Fordell Splint 37.60 52.00 3-73 1. 10 4.14 0.88 99-45 1.50 52.03 o Wallsend CO Elgin 61.6S 24.42 2.62 1-73 8.38 1.18 99.99 4.0 58-45 The following partial analyses of the ash of some coals and anthracites have been published : — Matters in- Matter soluble in Water. soluble Matter Total Name of Coal. in Water, soluble in insoluble in Acid and Amount of Ash in Coal Experi- menters. Hydro- Water. per cent. chloric Acid Newcastle 7.0 36-5 56.5 2.04 -, Wigan Cannel* 3-° 31-25 63-75 2.673 St. Helen's II. 25.0 64.0 S.oo K Stafford 14.0 41.0 45.0 0.912 I. 2.76 ]i. fl Oregon 2.0 lo.S 87. s 33-5 Anthracite 5-7 25-7 68.6 1-583 / Mean of 5 specimens from Clay Cross, ] Staffordsnire ... J 12.462 49.946 37-592 2.807 /Ron- ■ aids Sulphur in Coal. — A mechanical admixture of iron pyrites is remark- able in all kinds of coal, and is exceedingly objectionable for many of its applications. In some kinds it may be seen in distinct crystals ; in others it is so finely disseminated as only to be detected by chemical reagents. Sulphur also occurs organically combined in coal. The volatile or organic portion of coal is composed of the same elements as wood, peat, and brown coal; their relative proportions, however, are different. Nitrogen in Coal.f — Lunge ("Distillation of Coal Tar") gives the following statement of the average amount of nitrogen found by Dr. C. Meymott Tidy in various specimens of coal : — Coal from Nitrogen — per cent. Wales ._ Lancashire Newcastle Scotland 0.91 I-2S J-32 1-44 The greater part, if not all, of this nitrogen is recoverable as ammonia under certain circumstances, and, in view of the enormous quantities of coal consumed in this country, the importance of this source of ammonia is being rapidly recognized. * It was in the ash of these coals and those helow that Mr. Vaiix discovered traces of lead and copper. t Refer also to W. Foster, ' ' Jour, of Gas Lighting," 1882, vol. xl p. 1081, and " Jour. Ohem. Soc." vol. xliii. Trans. 1883, 105, and "Min.Proc. Inst. O.E."vol. Ixxvii. part iii. ; Watson Smith, " -Tour. Chem. Soc." vol. xlv. Trans. 1884, p. 144; Eamsay and Sidney Young, "Jour. Chem. Soc. Trans." 1884, p. 88 ; G. Beilby, "Chemical News," vol. xlvii. p. 221. COMPOSITION OF GOAL. 53 The following tables, showing the elementary composition of bituminr ous coal and some anthracites, are compiled from the results of recent experi- ments ; in the first, the names of the observers are added, whilst the others are derived from the Admiralty Coal Investigation : * — Description and Locality of Coal. Carbon. Hydro- gen. Oxygen. Nitrogen. Observers. Splint coal Cannel Wylani Banks, Newcastle i 74-823 6.180 5.085 Glasgow cool-field Wigan, Lancashire 82.924 6.491 10457 83-753 5.660 8.039 coal Cherry coal Caking J Parrot coal, Edinburgh Jarrow, Newcastle 67-597 5-405 12.432 Eichard- son 84.846 5.048 8.430 Chief coal from Glasgow Garesfield, Newcastle, Deep Bank 81.208 5-452 5239 11.923 87-952 5.416 coal South Hetton, Durham 83-274 5.171 3.036 Alais, Eochebelle 88.05 4.85 5-69 ^ Corbeyre, Eive de Gier 86.65 4-99 Rive de Gier, Grand Croix, marechal . 86.25 5.14 6.83 „ „ raffaud 86.59 4.86 7.II Flenu from Mons i . . . 83-51 5-29 9.10 Transi- 82.72 5.42 8.18 tion / Kive de Gier, Cimetiere, bourrue 80.92 5-27 10.24 forma- „ ,, batarde 83-67 5-61 7-73 tion ,, Couzon, ,, 81.45 5-59 10.24 gr. masse . 80.59 4 99 9.10 Decazeville, Dep. Avejron, Lavaysse . 81.00 5-27 8.60 I Epinac ..... 80.01 5.10 12.36 )Regnault Commentry, Dep. I'AUier . 81.59 5-29 12.88 >,Blanzy 75-43 5-23 17.06 Anthracite, Lamure, Dep. de I'lsere 88.54 1.67 5.22 Secon- dary orma Anthracite, from Macot 70.50 0.92 2.10 Obernkirchen, Lippe-Schaumburg 88.27 4-83 ■ 5-90 Ceral, Dep. Aveyron . 74-35 4-74 10.05 Noroy ... 62.41 4-35 14.04 Saint-Girons . , Belestat jJ®' 71-94 5 45 18.53 74-38 73-88 5-79 18.94 . Karsten Leopoldinengrube, Upper Silesia . Konigsgrube, from „ „ . Wellesweiler, Saarbriicken . 2-765 2.475 78.39 3.21 17.77 81.32 3.21 14-47 Salzer and Neuack, Westphalia 88.68 3.21 8. II Eschweiler 89.18 0.44 2.94 Hundsnak, Westphalia 96.02 3.207 6.45 MEAN COMPOSITION OP AVERAGE SAMPLES OP WELSH COALS. Locality, or Name of Coal. Specific Gravity of Coals. Carbon. Hydro- gen. Nitro- gen. Sul- phur. Oxy- gen. Ash. Pcrceni- agoof Cokeleft by each Coal. Aberaman Merthyr Ebbw Vale Thomas's Merthyr . A. 1-305 1.275 1.30 B. 89.78 90.12 C. 4.28 5-15 4-33 D. 1. 21 2.16 1. 00 E. 1.18 1.02 0.8s F. 0-94 0-39 2.02 G. 1-45 1.50 1.68 H. 85.0 77-5 86.53 * With refprence to the specimens for examination, Kichardson classified his according to the plan adopted in England (Thomson) into Splint, Oannel, Cherry, and Caking coal ; Ee'.nault arranged Ids according to their geological age ; and Karsten followed an arrangement of which we shall again speak pr«!seutly. The transverse lines in the columns of numbers correspond ■with the respeotiVB divisions in a like order. 54 COMPOSITION Of COAL. WELSH COALB- 1 Percent- Locality, or Name of Coal. Speeifio Gravity of Coals. Carbon. Hydro- gen. Nitro- Sul- gen. 1 phor. ! Oiy- gen. Ash. aire of Cokeieft by each Coal. A. B. C. D. 1 E. F. G. H. Duffiyn 1.326 88.26 4.66 1.4s 1-77 0.60 3-26 84-3 Nixon's Merthyr I-3I 90.27 4.12 063 1.20 2-53 1.25 W- Binea 1.304 88.66 463 1-43 I 33 1.03 396 88.10 Bedwas 1.32 80.61 6 01 1-44 ! 3-50 1.50 6.94 71.7 Hill's Plymouth Work 1-35 88.49 4.00 0.46 : 0.84 3-S2 2-39 ^?5 Aberdare Co.'s Merthyr . '•3' 88.28 4- 24 1.66 091 1.6s 3.26 85.83 Gadly's Niue-feet Seam . 1-33 86.18 4-3' 1.09 0.87 2.21 5-34 86.i;4 Resolven 1.32 79-33 4-75 1-38 S.07 in- cluded in ash 9.41 83-9 Mynydd Newydd I-3I 84.71 5-76 1.56 1.21 3-52 3.24 li^ Abercam 1-334 81.26 6.31 .77 1 1.S6 9-76 2.04 68.4 Anthracite, Jonea & Co. . I -375 91.44 3-46 21 0.79 2.58 1.52 92-9 Ward's Fiery Vein . 1-344 87-87 3.93 ,2.02 j 0.83 i in- cluded inasb 7.04 — Neath Abbey . . . . I-3I 89.04 5.05 1.07 1.60 3-55 61.42 Graigola • . . . 1.30 84.87 384 0.41 ! 0.45 7.19 3-24 l|-5 Gadly's Four-feet Seam . 1.32 88.56 4-79 088 1 1. 21 — 4.88 88.23 Machen Rock Vein . 1.297 71.08 4.88 .95 ^ 1-37 17.87 3.85 65.2 Birch Grove, Graigola 1.360 8 1.25 4.1S .73; .86 5-58 4-43 85-1 Llynvi . . .' 1.28 1 87.18 5.06 0.86 1 1.33 2.53 3-04 72-94 Cadoxton .... 1.378 87.71 4-34 1.05 1 1.7s 1.58 3-57 82.0 Oldcastle Fiery Vein 1.289 8768 4.89 1.31 1 0.09 3-39 2.64 79.8 Vivian & Sons' Merthyr . 1.299 82.75 5.31 1.04 ! .95 4.64 5-31 67.1 Llangennech . 1.312 85.46 4.20 1.07 1 0.29 2.44 6-54 83-69 Three-quarter Eook Vein 1-34 75-iS 4.93 1.07 2.85 5.04 10.96 62.5 Pentrepoth .... I-31 88.72 4.50 0.18 3.24 3-36 82.5 Cwm Frood Rook Vein '-2S5 82.25 5.84 I. II 1.22 3.58 6.00 68.8 Cwm Nant y Gros . 1.28 78.36 5.59 1.86 3.0I 5.58 5.60 65.6 Brymbo Main . 1.300 77-87 5.09 .57 2.73 9.52 4.22 ^l-^ Vivian & Sons' Rock Vawr 1.301 79.09 5.20 .66 2.41 8.34 4.30 58.6 Coleshill 1.29 73-84 S.14 1.47 2.34 8.29 8.92 56.0 Brymbo Two-yard . 1.283 78-13 S.S3 ■54. 1.88 8.02 5.90 562 Eook Vawr .... 1.29 77-98 4.39 0.57 0.96 8.55 7-55 62.50 Porthmawr .... 1-39 74.70 4.79 1.28 0.91 3.60 14.72 63.1 Pontypnol 1.32 80.70 5.66 I-3S 2.39 4-38 5-52 64.8 Pentrefelin 1-358 85.52 3.72 trace 0.12 4 55 6.09 85.0 MEAN COMPOSITION OF AVEHAGE SAMPLES OF NEWCASTLE COALS. Specific Percent? ase of Cokeieft by < ach Coal. Locality, or Name of Coal. Gravity of Coals. Carbon. Hydro- gen. Nitro- gen. Sul- phur. Ojy- gen. Ash. A. B. C. D. E. F. G. Willington .... — 86.81 4.96 1.05 0.88 5.22 1.08 7.2. 19 Andrews House, TanfielJ 1.26 85.58 5.31 1.26 1.32 4-39 2.14 65-13 Bowden Close — 84.92 4.53 096 0.65 6.66 2.28 69.69 Haswell Wallsend . 1.286 8347 6.68 1.42 .06 8.17 0.20 62.70 Newcastle Hartley 1.29 81.81 5.50 1.28 1.69 2.58 7.14 64.61 Hedley's Hartley •31 80.26 5.28 1. 16 1.78 2.40 9.12 72.31 Bates' West Hartley ■■25 8061 S.26 1.52 1.85 6.51 4.25 West Hartley Main . 1.264 81.85 5.29 1.69 1-13 7-53 2.51 59-20 Buddie's West Hartley 1.23 80.7s 5.04 1.46 1,04 7.86 3-85 Hastiaps' Hartley . 1.25 82.24 5.42 161 I ..35 6-44 2.94 35-6° Carr's Harlliy 125 79-83 5.11 1. 17 0.82 7.86 5-21 60.63 Davison's West Hartley . 1.25 83.26 5-31 \.ii 1.38 2.50 5-84 59-49 North Percy Hartley 1. 25 80.03 508 0.98 0.78 9.91 3-22 57.18 Haswell Ctial Co.'s Steamboat Wallsend . . . . 1.27 83.71 5.30 1.06 1.21 2.79 5-93 61.38 COMPOSITION OF COAL. 55 NEWOABTLE COALS — {continued). tooality, or Name of Coal. SpeciSc Gravity of Carbon- Hydro, gen. Nitro- gen. Sul- phur. oxy- gen. Ash. Percent- age of Coleleft by each Coal. Derwentwater Hartley Broooihill .... Original Hartley Cowpen & Sidney's Hartley A. 1.26 1. 25 I.2S 1.26 B. 78.01 81.70 81.18 82.20 C. 5-56 5.10 D. 1.84 1.84 0.72 1.69 E. 1-37 2.8S 1.44 0.71 F. JO.31 4-37 8.03 7-97 G. 3-73 3- 07 3.07 2.33 H. 54.83 59.20 58.22 58.59 MEAN COMPOSITION OF AVERAGE SAMPLES OF DERBYSHIRE COALS Locality, or Name of Coal. Specific Gravity of Coals. Carbon. Hydro- gen. Nitro- gen. Sul- phur. Oiy gen. Ash. Percent- age of Cokeleft by each Coal. A. B. C. D. E. F. G. H. Earl Fitzwilliam's Elsecar 1.296 81.93 4.85 1.27 .91 8.58 2.46 61 6 Holyland & Oo.'s Elsecar . 1-317 80.05 4.93 1.24 1.06 8.99 ,V73 62.5 Earl Fitzwilliam's Park Gate . 1.3" 80.07 4.92 2.15 1. 11 9.95 1.80 61.7 Butterley Co.'s Portland . 1. 301 8041 4.65 1-59 .86 11.26 1.23 60.9 Butterley Co.'s Langley . 1.264 77-97 5-58 .80 1. 14 9.86 4.65 54-9 Stavely 1.27 79.85 4-84 1.23 0.72 10.96 2.40 57.86 Loscoe Soft .... 1.285 77-49 4.86 1.64 1.30 12.41 - 2.30 52.8 MFAN COMPOSITION OP AVERAGE SAMPLES OF LANCASHIRE COALS Locality, or Name of Coal. Specific Gravity of Coals. Carbon. Hydro- gen. Nitro- gen. Sul- phur. 1 Oxy- gen. Ash. Percent- Coke kft by each Coal. A. B. c. D. E. F. G. H. Ince Hall Co.'s Arley 1.272 82.61 5.86 1.76 .80 7.44 I. S3 64.0 Haydock Little Delf 1.257 79.71 5.I6 .S4 .52 10.65 ,3-42 58.1 Balcarres Arley 1.26 83-.S4 .'i-24 .98 1.05 5.87 ,3- .32 62.89 Blackley Hurst 1.26 82.01 S-S'! 1.68 1.43 5.28 4.05 57.84 Ince Hall Pemberton Yard 1-348 80.78 6-23 1.30 1.82 7.53 2.34 60.6 Haydiick Kushy Park 1.323 77.65 s-ss ..SO 1.73 10.91 3.68 59.4 Moss Hall Pemberton Four-feet 1.258 7':-';3 4.82 2.05 3.04 7.98 6.58 55.7 Haydock Higher Florida . I.2I8 77.33 ,1.S6 I.OI 1.03 12.02 3.05 51.1 Ince Hall Pemberton Four-feet . 1.276 77.01 3-93 1.40 1.05 5.52 1.09 57. 1 Blackbrook Little Delf . 1.26 82.70 s-ss 1.48 1.07 4.89 4.31 58.48 King ..... Rushy Park Mine 1.300 73.66 7^.76 5.30 1.68 1.58 9.06 8.72 62.4 1.28 ';-23 1.32 1.01 8.99 56.66 Blackbrook Kushy Park . 1.27 81.16 5.99 I-3S 1.62 7.20 2.68 58.10 Johnson & Wirthington's Kushy Park . . . . 1.28 79.50 .ws I 21 271 9.24 2.19 57.52 Laffak Eustiy Park 1-35 80.47 ,'i-72 1.27 !..« 8.33 2.82 56.26 Balcarres Hai(;h Yard 1.28 82.26 S-47 1.25 1.48 5. 64 3.90 66.09 Haydock Florida Main 1.267 77-49 .S-.SO 1.27 .88 12.84 2.02 54-4 Wigan Four-feet 1.209 78-86 ";-29 .86 1.19 9.57 4.23 60.0 Ince Hall Pemberton Five-feet . 1.269 68.72 4.76 2.20 1.3s 18.63 14.34 56.5 Cannel (Wigan) 1.23 7923 608 1. 18 1.43 7.24 4.84 60.33 Ince Hall Co.'s Furnace Vein . 1.314 74-74 ■;.7i I. '53 .96 13.52 4.04 58.4 Balcarres Lindsay . 1.26 83.90 5.66 1.40 1.51 5.53 2.00 57.84 Caldwell & Thompson's Kushy Park 1.271 76.17 .';.46 1.09 .91 14.87 1.50 58.7 Balcarres Five-feet . 1.26 74.21 503 .77 2.oq 8.69 9.21 55.90 Moss Hall Pemberton Five-feet 1.283 7616 5.35 1.29 1.05 10.13 6.02 56.1 Moss Hall Co.'s New Mine 1.278 77.50 5.84 .98 1.36 12.16 3.16 57.7 Caldwell & Thompson's Higher Delf 1.274 7540 4-*i3 1.41 2.43 19.98 5-95 54.2 Johnson & Wirthington's Sir John . '■3' 7286 4.98 1.07 1.54 8.15 11.40 56.15 56 COMPOSITION OF COAL. MEAN COMPOSITION OF AVERAGE SAMPLES OF SCOTCH AND VARIOUS OTHER COALS. ■ Locality, or Name of Coal. Specific Gravity of CoalB. Carbon. Hydro- gen. Nitro- gen. Sul- phur. Oxy- gen. Ash. Coke left bveacta Coal. A. B. C. D E. f. G. H. Wallsend Elgin . I 20 76.09 5-22 1.41 1-5.3 .5-05 10.70 5«-45 .3 Wellwooil .... 1.27 ' 81.36 6.28 1-53 1-57 6-37 2.89 59-15 g. Dalkeith Coronation Seam . 1. 316 76.94 S.20 trace 0.38 14- .37 3.10 5.3-5 ^ Kilmamook Skerrington 1. 241 79.82 5.82 -94 .86 11.31 1-25 49-3 -fe Fordel Splint 123 79. S8 5-50 I-I.S 1.46 »-3.3 4.00 52-03 o Grangemouth 1.29 79-85 ,.28 1.15 1.42 8.58 .3.52 56.6 xa Eglinfon 1.25 8008 6.50 1-55 1.38 8.0s 2.44 54-94 Dalkeith Jewel Seam 1.277 74-55 5-14 O.IO 0.3.3 15-51 4- .37 498 § rColeshill Co.'s Bagillt Main 1.269 88.48 S.62 2.02 1.36 0.86 1.62 55-« •2 Ewlowe I 275 80.97 4.96 1. 10 1.40 8.20 .3-37 545 ^ (ibstock 1. 291 74-97 4-«3 .88 I.4S 11.88 5-99 50.8 AVERAGE COMPOSITION OF COALS PROM DIFFERENT LOCALITIES. Locality. . Specific Gravity of Coal. A. Carbou. Hydro- gen. Nitro- gen. Sul- phur. Oxy- gen. Ash. Percent- age of Cole left byeacb Coal. H. verage .of: B. C. D. E. F. 36 samples from AVales . I-315 83.78 4-79 0.98 1-43 4.15 4.91 72.60 18 , , Newcastle 1.256 82.12 5-31 1-35 1.24 .5-69 .3-77 60.67 28 , , Lancashire 1.273 77.90 5-.32 1.30 1.44 9.53 4.88 60.22 8 „ Scotland 1.259 78-53 5.6. 1. 00 1. 11 9.69 403 54.22 7 „ Derbyshire 1.292 79 68 4 94 1.41 I.OI 10.28 2 65 5932 AVERAGE COMPOSITION OF FOREIGN COALS. Locality. Specific CSavity of Coal. Carbon. Hydro- gen. Nitro- gen. Sul- phur. Oxygen. Ash. A. B. ■ c. D. E. F. G. South Cape . — » 63.40 2.89 1.27 0.98 I.OI 30-45 Mount Nicholas Break 0' Day — 57-37 3-91 1. 15 0.90 9.10 27-55 Van 'I'ingal — 57-21 ,3-38 1.20 1.32 7.80 29.09 Die- Jerusalem — 68.18 3-99 1.62 1. 12 5-89 19.20 men's Dquglas River, East Coast — 70.44 4.20 I.U 0.70 9-27 14-38 Land Tasman's Peninsula — 65-54 3-36 191 1.03 175 26.41 Coals Sclionten Island . — 64.01 3 5.5 0.94 0.85 3-38 27.17 Whale's Head, South Cape — 65.86 3.18 1. 12 1. 14 7.20 21.50 Adventure Bay — 80.22 305 1.36 1.90 4.80 8.67 Sydney, New South Wales — 82.^9 5-32 1.23 0.70 8.32 2.04 Borneo fLahman kind) . „ Three-fegt Seam 1.28 64.52 4 74 0.80 1.45 20.75 7-74 1-37 54-31 503 098 1. 14 24.22 14.32 „ Eleven-feet Seam 1. 2 1 70.33 S.41 067 1. 17 19.19 3-23 Formosa Island . 1.24 78.26 570 0.64 0.49 10.95 3-96 Tancouver s „ — 66.93 5-32 1.02 2.20 8.70 15-83 Lignite, Trinidad . — 65.20 4-25 1-33 0.69 21.69 6.84 f Conception Bay 1.29 70.5s 5.76 0-95 1.98 13-24 752 Port Famine . — 64.18 5.33 050 1.03 22.75 6.21 Chili Chirique — 38.98 4.01 0.58 6.14 13-38 3691 Coals Laredo Bay . — 58.67 5-52 0.71 1. 14 '7-33 16.63 Talcahnano Bay — 70.71 6-44 1.08 094 '3-95 6.92 Pata- V gonia Coals Colcurra Bay — . 78.30 5-So 1.09 1.06 8.37 5.68 Sandy Bay, No. i — . 62.25 5-05 0.63 I-I3 17-54 13-40 „ „ No. 2 — 59-63 5.68 064 0.96 17-45 15.64 COMPOSITION OF ANTHRACITE. 57 Some few elementary analyses of American coals have been furnished by Professor Johnson, which will be found in a table below, in connection with the relative value of fuel. Although nitrogen is found in all kinds of coal (as shown in the last tables), yet no such intimate relation has been traced between it and the qualities of the coal, as is the case with the three other elementary con- stituents. The sulphur in coal is partly organic, partly in the form of calcic sulphate, and partly as pyrites. With the increase of carbon, the colour of the coal becomes of a darker brown until it is quite black, the lustre gradually rising from that of pitch to a vitreous hue. On the contrary, coal is harder when the amount of carbon is diminished, as in some varieties of cannel coal. The hardness has been said to depend on the relative proportions of hydrogen and oxygen, and to be augmented by an increase of the latter. Anthracite. — The oldest of all kinds of fossil fuel, anthracite, belongs to the transition formation, and must be regarded as the last product of the mouldering process. Notwithstanding its similarity in outward appearance to other species of coal, it distinctly differs from them, both in composition, and by the manner in which it burns. The relation of anthracite to common coal is the same as that of the latter to brown coal. Certain kinds of coal, as those of Lamure and Macot in the table, are classed with the anthracites, on account of the similarity of their properties; these,. however, are not the result of an advanced stage of the process of decay, but of the agency of heat accompanying the later elevations of primary rocks. Anthracite is eminently homogeneous and without impressions of plants ; it is black, has a decidedly vitreous lustre, an iridescent play of colours, and a conchoidal, sharp-edged fracture. Its structure is massive. The amount of ash, com- position, and specific gravity of specimens of this kind of coal are given in the next table. Regnault found 0.37, Jacquelin 0.58 to 2.85 nitrogen. The ash consists of silica, alumina, and oxide of iron ; and, according to more recent observa- tions, it also contains chlorides, which, volatilizing during combustion, damage the metalHc portions of the stove or grate in which such coal is used. Locality of Anthracite. Specific Gravity. Carbon. Hydro- gen. Oxygen. Nitrogen. Sulplmr. Ash. Name of Observers. Pennsylvania, America Wales, Swansea Mayenne, town and Dep. Mire Baoonniere .... Rolduc, near Aix-la-Chapelle Swansea SM4, Dep. de la Sarthe Vizille, Dep. de I'Isfere tere ... Wales, Jones & Co. . Slievardagh, Ireland 1.462 1.348 1-343 1-367 1.270 1.750 1-730 1.650 I-37S 1-59 89.21 91.29 90.20 90.72 90.58 87.22 94.09 94.00 91-44 80.03 2-43 2-33 4.18 3-92 3-60 2.49 1.85 1.49 3-46 2-30 3-69 4.80 3-37 4.42 4.10 3-39 2.85 3-5« 3-58 N. 1 S. 4.67 1.58 2.25 0.94 1.72 6.90 1.90 4.00 1.52 (Includ- ing 0.) 10.80 ■ Eegnault ■ Jacqueliu ) Admiralty r Coal Inves- ) tigation 0.23 1 6.79 Professor Johnson gives the following composition for the ash of some American anthracites : — 58 COMPOSITION OF AMERICAN ANTHRACITES. .0 t t 11 84.87 3-84 7.19 0.41 Aberamau ji 90-94 4.28 0.94 I.2I Anthracite — 9144 3-46 0.79 0.21 »> Slievardagh, Ireland 31 80.03 2.30 0.23 )> Vizille Jacqiielin 94.09 i.8s — it Swansea Eegnault 91.29 2.33 1 0.82 0.45 In fact, all three ingredients have disappeared in certain proportions, whilst the carbon, which is always the preponderating element, is least affected. rire-damp. — The evolution of inflammable gases at the surface of the earth has long been known to exist near the Caspian Sea, where they accompany the naphtha springs, and on the Schagday, at a height of 7,834 feet. The Holy Fires of Baku are fed by a gaseous mixture containing fire-damp or marsh gas, with 6 per cent, of nitrogen, and from i to 5 per cent, of carbonic acid. Marsh gas or methane is also found at Pietramala in Tuscany, at Klein-Saros in Siebenburgen, and in several other localities. It enters also into the composition of the gases which escape from various celebrated springs ; as, for example, in the — Hot spring of Aachen, to the extent of Sulphur spring of Neiindorf Mineral spring of Niederlangenau Hercules baths of Orsova . Mineral waters of Harrogate .26 — 1.82 per cent. .17—1.46 „ 8.02 .38—0.88 „ „ (cub. inches •15— 5-»4 1 per gallon On the hill-side near Kangea, North-western India, Mrs. Colin McKen- zie, in her work on " Life in the Mission," &c., says many streams of gas have been ignited, the principal of which are enclosed in a temple by the Hindoos, who look on them with great veneration. The same ga-s is frequently met"~with in salt-mines, where it was iirst noticed by Guettard and Marcel de Serres.* Bremer also describes an inflam- mable gas which escaped from a fissure in the bed of marl in the salt-mine at Szlatina in Hungary, and which was employed to light the mine. A similar gas escapes from an old shaft at the salt-mine, Gottesgabe, and it has been noticed at Fredonia and other points near Lake Erie, and more recently " Mr. T. Hugh Bell mentions (" Jour. Iron and Steel Inst.," vol. i. 1885, pp. 1S0-182) that gas of the composition, marsh gas 76.9 per cent., ethylene 6.3 per cent, nitrogen 16.8 per cent. by volume, was observed issuing from a bore hole put down by his firm to the salt beds underlying Middlesbrough. go FIRE-DAMP. at other places in N. America, especially in the neighbourhood of Pittsburg, Pennsylvania, where it is largely used for industrial purposes (see Natural Gas). It constantly accompanies the salt springs at Marietta in Ohio, and is very common in the salt district of, Tseu-lieou-tsing in China, where it is used for the purpose of illumination, and for evaporating the liquor of the salt pans. This gas is also the chief constituent of the gaseous mixture which escapes from the remarkable decrepitating salt of Wieliczka, when it is dissolved in water, first noticed by Dumas, and which, of course, must exist in a very condensed state. Bunsen found it to contain — Marsh gaa 84.60 Carbonic acid . 2.58 Oxygen . 2.00 Nitrogen . 10.35 9953 Bischof found the gas which was discharged from a bore-hole sunk for an artesian well in the Princedom of Schaumberg in Germany, to contain, after the separation of the carbonic acid — Marst gas . . 79- 10 Olefiant gas 16.11 Nitrogen . . . . 4.79 100.00 Marsh gas is, however, chiefly found in coal-mines, although its exist- ence in brown coal workings has not yet been satisfactorily proved. The explosions which sometimes occur in coal-mines, and which are generally attended with such fatal consequences, are caused by the introduction of a naked ilame, employed for illumination, or produced by gunpowder or other explosive substances used in blasting operations in the mine, or a vivid spark of red-hot metal in a mixture of marsh gas with other gases and common air. It would seem, however, that an explosion only follows the introduction of a vivid spark of red-hot metal when olefiant gas is present, as Mr. Clarke mentions having seen the picks of the workmen strike fire in an inflammable mixture without causing an explosion. This circumstance speaks for the correctness of the analyses of the gases from the English mines which are given in the table on p. 61, and which show no olefiant gas. J. Mey^ * li*is recently instituted a series of experiments to determine the circumstances under which fire-damp may be ignited by sparks produced either by the steel tools used in working in hard rock, or by the friction of pieces of rock against one another. Two to four sharp-edged pieces of steel were pressed, with a pressure of 9 lbs. to 13 lbs., against the periphery of a grindstone of carboniferous sandstone 15.75 inches diameter, and 3.15 inches thick, running at a rate of 250 to 300 revolutions per minute. A continu- ous stream of sparks of varying intensity was produced, but an explosion was produced only when some of the sparks had an intensity equal to or exceeding the igniting point of the gas. To produce such ignition it was necessary either to force a current of gas against the sparks, or to produce the sparks in the midst of the explosive mixture. Both ordinary illumi- nating gas and natural gas from a " blower " were, used, the latter showing on analysis : Marsh gas, 96.00, carbonic anhydride, 1. 10, oxygen, o.io, other gases, 2.80. No heavy hydrocarbons or free hydrogen could be detected. The illuminating gas was readily ignited after a few seconds, but it was much more difiicult to ignite the specimen of fire-damp which was used. » Oust. Zeit. fib- 13. u. fi;, vol. xxxiv. pp. 379-82, and 398-401 ; "Jour. Iron and Steel Inst.," ii. 1886. p 881. ANALYSES OP FIKE-DAMP. 6i When the grindstone was moistened with water, the danger of ignition was consideriably lessened. When pieces of rock were held against the grindstone with a pressure of about 2 2 lbs. , ignition was more readily obtained with both gases, but it was necessary for the rock to be sandstone. A revglving stone of shale with pieces of shale pressed against it produced no sparks. With reference to the temperatures necessary for the ignition of different gases, the French Commission on fire-damp give the following: — Heavy oaiburetted hydrogen Hydrogen . Carbonic oxide Marsh gas . Degrees Centigrade. 55° S8o 650 780 Experiments made by the German Commission, however, show that the temperature at which fire-damp ignites is higher than would be indicated by its composition, as they were able to fuse wires of silver and copper in the explosive mixture without igniting it. The mixture of gases evolved from coal, known in England under the term Fire-damp, and in France called Grisou, has been repeatedly analysed. The gas from different localities exhibits a general uniformity in composition, consisting principally of marsh gas, with varying quantities of carbonic acid, nitrogen, hydrogen, atmospheric air, and sometimes olefiant gas and sul- phuretted hydrogen. The following analyses have been published by different chemists: — TABLE OP ANALYSES OF FIRE-DAMP. Colliery or Pit. Seam or Source of Gas. Specifio Gravity. 1 s 1 '3 < '3 1 1 Authority or Analyst. 1 § 1 3 •5991 .6410 .6079 •5901 .6236 •8325 ■7724 .7677 .9662 Wallsend . Hebburn Jarrow Borraton . Eillingworth . Hetton Pensher Townley Well-Gate Gateshead Cwm-Twrcli . Wellesweiler . Gerhardt . Bensham . Pipe above ground . 24 feet below Bensham . Ditto (a month after) Bensham . Five-quarter . Low Main Ditto, II fathoms lower . Yard Coal High Main Low Main Main, 100 fathoms HuttoD, 175 ditto . Hutton Waste, 125 ditto . Three-quarter Seam Five-quarter ,6024 .6327 .6381 .6209 .6000 .6196 .8226 .6306 .7800 •747° .9660 .5802 91.00 77.50 92.80 91.80 92.70 86.50 81.50 83.10 93.40 79.70 89.00 91.00 85.00 37.00 82.50 66.30 50.00 50.00 7.00 56.17 98.20 94.20 19.30 87-43 79.84 9.00 18.50 11.00 9.00 8.00 46.50 ■23-35 23.00 6.00 82.00 33-15 21.10 6.90 6.70 6.40 11.90 14.20 4.90 12.30 7.00 16.50 16.50 6.32 27.00 44.00 11.00 4.68 1.30 4-50 63.80 2.22 14.36 0.60 0.90 0.60 0.40 3.00 1. 00 1.30 15-50 1.30 0.30 0.70 0.90 1.60 2.10 1.70 4°3 6 00 0.50 0.80 4.3° 3-9° 3.00 6.05 1.90 Turner Playfair Graham Turner Playfair Turner Graham Kichardson Turner Biehardson Playfair Graham Playfair Bischof The presence of oxygen in some of these mixtures has evidently arisen from the difiiculty of collecting the gas in a state of purity. The proportion of nitrogen in many of the samples exceeds that existing in atmospheric air, and supports the opinion of Mr. T. J. Taylor and others that fire-damp is not now spontaneously generated by or in the coal; this is confirmed by 62 OCCUEEENCE OF FIEE-DAMP. the extremely variable proportions in which the gas issues locally. Mr. Clarke has also noticed, that as the depth increases, and the pressure of the superincumbent strata becomes greater, the gas is more free from carbonic acid, and more inflammable, while the quantity of water given off diminishes and in some oases disappears, but when present, generally contains a quantity of salt in solution. Bischof indirectly confirms this conclusion, as the result of modern investigations shows that the nitrogen is the product of the decomposition of organic matter under circumstances which do not exist in coal-mines. The constituents of these gaseous mixtures, when compared with the known composition of wood and coal, enable us to form a veiy probable conjecture respecting the mode of their formation. It is admitted that coal is the product of the gradual decomposition of wood by a kind of moulder- ing process under pressure, in the presence of water, and with a very limited supply of air. These agencies have all had a share in the transformation, but we are unable to trace the influence which each may have separately exerted towards the ultimate result, although it is probable that, in the formation of coal from wood, marsh gas and carbonic acid are amongst the products eliminated ; carbonic acid, in fact, frequently abounds in the old workings, and being absorbed by water gives rise to the acidulous springs so abundant in the coal measures. The small proportion of nitrogen contained in fire- damp is derived from the nitrogenous substances naturally existing in wood. The occurrence of defiant and hydrogen gases which are sometimes found must be explained in some other manner, but in reference to the former, it has been remarked that the coking coal from Garesfield, near New- castle, contains the elements of Cannel coal, minus the constituents of olefiant gas. Henry explains the formation of fire-damp by the action of water on carbon in the following manner : — 2C + 2H,0 = C0,+ CH,. This, however, is extremely improbable, and is moreover inconsistent with the composition of fire-damp ; a high temperature during the formation of coal would probably have given rise to carbonic oxide, a gas which has not been detected in any of the samples analysed j whilst the fact that a similar mixture of gases is observed to rise from the mud of stagnant pools where organic matter is in a state of eremacausis, speaks strongly in favour of the mouldering process. The large volume of gas which issues from coal in some localities with immense force, in the form of blowers, shows that the gas must be retained under enormous pressure. Naphtha, which consists principally of liquid hydrocarbons, is known to exude in considerable quantities from some of the coal formations, a spring of this description being only comparatively recently exhausted at Riddirigs, in Derbyshire. The natural petroleum springs in America, the Caucasus, France, on the Rhine, and in other places, appear to owe their origin to the same source. Some coal, according to Reichenbach, is impregnated with hydrocarbons, which may be separated from it by distillation with water. A heat greatly below redness is sufficient to separate carbon and hydrogen, not only in the form of gas, but as liquid petroleum, as in Young's processes. Most varieties of coal yield this product, but those possessing the character of Boghead have long been employed for the artificial production of illuminating and lubricating oils. Mr. Clarke considers that these blowers depend on the locality; for instance, in "fiery seams," where /aitZfts are found running in the direction of the "facings," or the cleavage of the coal-bed — thus forming, as it were, a natural barrier against the exit of the gas — many of the greatest dis- charges of fire-damp recorded in the north o*' England have occurred. He OCCDEEENCE OF EIEE-DAMP. 63 has also found, in driving across the facings or cleavage of the coal, that more gas is liberated, as it were draining the seam on each side, in the same way as if the seam were loaded with water. The gases are evolved from all the minute fissures of the coal, generally in a slow and imperceptible manner, but at oiher times with a distinct hiss- ing sound, as of a confined gas escaping through small apertures from a vessel in which it has been enclosed. This is more frequently noticed when the newly exposed surface of the coal is moistened with water. The gas sometimes exists in such abundance, and of such great tension, more especially in the neighbourhood of faults or dislocations of ithe strata, that it will dislodge masses of coal, several tons in weight, with great violence, and, mixing with the air, fill the passages of the mine for a considerable distance with an explosive mixture. It is the occurrence of- these bags or reservoirs of gas in the workings, which renders mining operations in the deeper coal-beds so dangerous. They are seldom met with in working the upper strata, as the gases find more easy vent through the pores of the superincumbent rocks, and often make their way to the surface through natural channels. Discharges of gas of this kind have been observed in many localities, often at considerable distances from the coal measures. One was described by 'Thomson as occurring at Bedlay, near Glasgow, which consisted of 87.5 parts of "fire-damp" and 12.5 parts air, and continued to burn for five weeks after it was ignited. At Wallsend Colliery, near New- castle, as much as 95 cubic feet of gas per minute was evolved from the workings, which, being conveyed in pipes, was used for years in lighting the village, and for a short period at the neighbouring railway station. In all these cases, the gases have a similar origin, but being confined in the deep coal-seams without any natural outlet, they accumulate to such an extent as to acquire very great tension. The manner in which these dangerous accumulations of gas sometimes occur is well illustrated and explained by the following letter, comprising drawings and descriptions, by Mr. Clarke, forme ^-ly newer of Wallsend Colliery : — " Walker Colliery, near Newoastle-on-Tyne, "December 13, 1846. " The ' high main coal-seam ' is here found at the depth of 100 fathoms from the surface, nearly all of which has been wrought out by difl'erent shafts, and the 'low main coal-seam ' (which is very partially worked) at 160 Fig. 6. n Jane Pit. o Ann Pit. P Furnace, y High Main Coal Seam, o Low Main Coal Seam. 64 OCCUERENCE OF FIRE-DAMP. fathoms, or 60 fathoms below the previous seam. It is about six feet iri height, with two thin bands or layers of ' flue metal ' running through it. " The air descends by the Jane Pit shaft into both seams, and the Ann Pit shaft is the upcast from both. There is a furnace constantly burning in the high main seam at this shaft, by which the ventilation in that seam is carried on; the heated column of air in the same shaft also causes a sufficient draught to ventilate the low main seam, as shown in Fig. 6. " I shall now give some particulars of two very considerable discharges or eruptions of gas which have taken place in the low main seam near the Jane Pit shaft. " The first was encountered on November 13th last, when approaching a ' slip-dyke ' or fault, marked a in Figs. 7 and 8, from the ' back or sUp ' of which it displaced a mass of coal about 8 feet long on one side, 4 feet on the other, and nearly 6 feet high, weighing, with the disintegrated or ' danty ' coal which had wasted from the shp of the dyke, about 1 1 tons. Fio. 7. Fig. 8. Jane Pit shaft. Upcast to west of 10 feet. This line in centre of the drift represents the wood brattice to carry the currents into the face of each place. Fio. q. g Jane Pit. li. Whin Dvke. ii Coal partially coked. Is, Whin Stone. I Upnast south of 14 feet. tu Low Main Coal Seam. V Block of coal displaced, together with w "Danty" Coal. X Upcast to west of 10 feet. N'.B.- -The arrows in all cases show the direction of the currents of air. " On the displacement of this block, and the discharge of fire-damp which succeeded, being observed by the two men working in the drift, they imme- diately secured their lamps, one of which had been partially covered with OCCUKRENCE OF FIRE-DAMP. 65 the fall of coal, but continued to burn, while the other nearest the current of gas had been put out. They then drew down the wick of the remaining Ughted lamp, and hastened to apprise the other men in the pit, extinguishing all the lamps as they proceeded, after which they retired to the shaft, according to the printed regulations. "From observations made at the different places where men were working, the area of drifts or passages fouled at the same moment amounted to 41,681 cubic feet. The point marked b was the most distant place north in the return air channel, where there was any person at work in the mine although it is extremely probable that the drift would be fouled beyond this spot. After the lapse of from fifteen to twenty minutes, there were no traces of fire-damp. "The quantity of air circulating in this part of the mine was 10,483 cubic feet per minute, the current passing at the rate of 6.24 feet per second, or 4^ miles per hour. The area of that portion of the drift in which this current was confined was about 28 feet." "The second violent discharge of gas took place on December loth. Before proceeding further, I may notice the precautionary measures that were taken in again approaching this slip-dyke. A bore-hole was kept constantly in the coal in advance of the face of the board (a) to prevent the recurrence of such a discharge, and when the last bore-hole had reached the ' slip ' of the dyke and the face of the working, within three yards of it, another bore-hole was put in to touch the seam on the rise or west side of the dyke where it penetrated the coal. No discharge of gas issued from it, and the dyke was fearlessly approached, the coal on the east side being taken away to the slip, and a portion hewn out on the rise, or opposite side of the dyke. The position of the seam being thus ascertained, a portion of the roof was removed to carry up the tramways. While this was being done, the ' danty ' or disintegrated coal in the slip of the dyke, above the point where the bore-hole has passed through it, was violently forced out with a noise resembhng the exhausting of an immense high-pressure steam- engine, which continued some time, and a discharge of gas followed which filled the workings or passages to a distance of 641 yards in length, or an area of about 86,306 cubic feet. At a distance of about 400 yards from the pbint of discharge, one of the deputies, who had been with some of the workmen conveying materials from the Ann Pit shaft, met the foulness, and on discovering his lamp to be filled with flame, he drew down the wick. The gas continued to burn in the inside of the gauze for about ten minutes, by which time it was red hot, when the current of air having ceased to be explosive, the flame was extinguished. This lamp shows indications of having been exposed to strong heat, the particles of coal-dust attached to the outside being burnt red. At a distance of 641 yards, the foulness was met by four men, who, on discovering their lamps to be on fire, immersed them in a suTnp or pool of water near at hand. It will be seen from the sketch, Fig. 7, that the same dyke had been nearly reached at the spot marked c when this eruption took place. " The velocity of the air, and the time that the gas continued to discharge, render it highly probable that the drift in the direction of the Ann Pit would be foul for a considerable distance beyond the point observed. The quantity of air circulating in the passages at the time was about 16,000 cubic feet, with a velocity in the principal channels of 3.55 miles per hour, and in some of the others considerably quicker. In from twelve to fifteen minutes from its first issue, all traces of the fire-damp had disappeared, excepting to within a yard of the point of discharge, where it mixed witn the air, and was carried off. At the blower, the temperature was con- 66 ATMOSPHERIC PRESSURE AND FIRE-DAMP. siderably higher than in the other parts of the mine, which ranged a day or two before at 6i°, while at the surface it was 32". " It need only be stated that happily no unprotected light had been allowed to be used in the workings of this seam from the commencement. " These facts prove that in the best state of our present known mode of ventilation, the working of the fiery seam is not safe without the use of protected lights, and assists in explaining how some of the many great explosions in this and other neighbourhoods may have been occasioned, when they could not be attributed to a deficient supply of aix-. " On both of these occasions the barometer stood at 30.5." The pressure of the atmosphere was at one time thought to exert con- siderable influence on the rapidity with which the gases exude from the fissures of the coal, and accidents were supposed to occur immediately after a sudden fall in the barometer. Mr. Clarke, who made a series of observa- tions, extending over some months, on the evolution of gas in mines connected with the indication of the barometer, arrived at the conclusion, however, that the barometer did not invariably indicate the discharge of fire-damp. In some pits, where candles were generally employed, safety-lamps were lighted when the barometer fell to 29.5 inches, and the candles were ex- tinguished. In others, the men retired when the mercury was observed to be as low as 295 inches. When the barometer falls to 29 inches, the gas hisses in some localities in escaping from the fissures of the coal, while, upon a sudden rise to 30 inches, a similar sound is supposed to be occasioned by a return of the air through the pores and crevices. It is now generally admitted that the variations of atmospheric pressure have little eSect on the rate of the escape of fire-damp from the working faces in coal mines, but that where a large reservoir of gas, such as a " goaf " or unventilated space, exists, a large quantity of gas may be liberated from it on the occasion of a fall in the barometer.- In this case, however, the gas being much more sensitive to atmospheric change than the mercury, the escape of gas takes place before the barometric indications are sufficiently declared. It has been suggested * that sudden outbursts of gas are connected with the motions to which the earth's crust is subject, and that the observation of earth-tremors or seismic movements might be made use of in order to foretell such outbursts. In 1876, Mr. Hall, one of H.M. Inspectors of Mines, made some experi- ments to show how greatly the escape of gas is increased by the exhaustion of air from a surface of coal.t "An iron tube (4 inches diameter and 4 feet long) was tamped into a bore-hole 18 inches deep, and a pressure gauge was attached to it by a side tube close to the face of the coal. In the tube was an air-tight piston initially at the bottom of the borerhole. When this piston was withdrawn, there would be a considerably diminished pressure on the 12 or 13 square inches of coal exposed at the end of the hole, and if gas only entered the tube at its normal rate of escape the gauge would indi- cate the formation of a partial vacuum as soon as the piston passed the junction of the branch-pipe with the main-pipe. In one experiment, in the Bastian seam, a sUght diminution of pressure was thus produced, but almost instantly the pressure due to the gas, or to air which had been drawn into the coal and become highly charged with gas, was sufficient to balance the atmospheric pressure. When the piston was forced back into the tube the g9,s was driven back into the coal and escaped from points, probably small crevices, spread over an area of the face to a distance of 4 to 5 feet from the • See M. Walton Krown in " Proc. N. of E. IdsI. M.E.," vol. xxxiii. pp. 179-1S3, 165-178. f See "Final Report Royal Commission on Accidents in Mines," 1886, p. 21. ATMOSPHERIC PEESSUEE AND FIEE-DAMP. 6/ bore-hole, and wlien lighted these jets of gas appeared as small flames distributed over the face. " Similar experiments were tried in the Wigan 9 feet, a very fiery seam, and th'e Pemberton 4 feet, a seam considered to make very little gas, but in neither case did the gauge show any diminished pressure in the tube, the gas at atmospheric pressure followed up the piston as fast as it could be withdrawn. " The effect on the escape of gas from coal due to a diminution of the pressure in the air of a mine has lately been put to the test of direct experiment on a large scale in a pit belonging to the Archduke Albert, at Karwin, in Austrian Silesia." These researches are still in progress, but in 1886 a preliminary report was issued, which showed some remarkable results. " In addition to a continuous registration of the height of the baro- m.etric column in the pit, and frequent chemical analyses of the air passing up the fan-drift, the effect of partially exhausting the whole pit has been tried. The down-cast shaft having been closed as air-tight as possible by a wooden platform covered with clay, the fan was maintained in action at its usual speed — eighty revolutions per minute, giving a difference of level of 60 mm. (2.36 inches) in a water-gauge in the fan-drift, and the quantity of gas leaving the pit was calculated from the velocity of the current in the fan-drift and the composition of the air. In consequence apparently of a leakage from another set of workings having a distinct system of ventilation the height of the barometer in the mine was only reduced 2.5 mm. (about 0.1 inch) below that which it would have had if the down-cast shaft had been open, but the quantity of gas passing out of the mine was increased by about 83 per cent. The existence of old workings, the action of which under diminished pressure is well known, complicated the results obtained by an experiment on an entire mine. A similar experiment was therefore tried in a district (the Karl-Flotz) not connected with any goaf, and which consisted only of an incline 190 metres (20& yards) long, with an accom- panying travelling road. In this district, an artificial reduction of pressure to the extent mentioned above caused an increase of 40 per cent, in the output of gas. In other experiments, the shaft from which the leakage occurred was also closed, and a diminution in the height of the barometer of 4 mm. was artificially produced, with the result that in the Karl-Flotz district the output of gas was apparently increased in the ratio of 235 to 100. Numerical determinations in this last experiment were rendered uncertain by the circumstance that, after the exhaustion had continued for seven hours, the current was found not sufficiently strong to move the anemometer, and the fan seemed to have ceased to extract air from the pit, although the difference of level in the water-gauge in the fan- drift remained as before — viz., 60 mm. " If the indications of the anemometer used in these experiments can be trusted, when running at a low speed, it is very difficult, with the information at present available, to reconcile the large increase of gas observed in these experiments with the fact that no equivalent increase was found when the height of the barometer fell, from natural causes, to the extent which had been artificially produced." Another cause which probably affects the quantity of gas escaping from the face of coal has been pointed out by Mr. Hall, who regards the possibility of an increased escape of gas from a face of coal on which the pressure is reduced as a matter of importance in considering the effect of a blown-out shot. " The rush of products of explosion from such a shot must cause a lateral diminution of pressure in the air, and under certain circumstances this- may affect the gas in the coal. Pro- F 2 68 SUDDEN OUTBURSTS OF FIEE-DAMP. bably the conditions most favourable to this action are attained when a shot is fired in the end of a comparatively narrow heading and blows out along the heading. The pressure on the wal forming the sides will then almost certainly be more or less reduced, and an extra amount of gas may be thus suddenly thrown into the air. If a second shot be fired very soon after the first shot, in the end of the same heading, and it also blows out, or emits flame, it is highly probable that the ga^ just placed in its course will be ignited and produce a blast ot a formidable character." The British Royal Commissioners appointed to report on accidents in mines report that eruptions of fire-damp, which have been termed " sudden outbursts " and " instantaneous discharges," have been much more frequently observed during the last thirty-five years, and that they appear to become more numerous with the augmentation of depth in our own collieries and in those of Belgium. Accounts of these are to be found in the " Transactions of the Midland Institute of Engineers " and other engineering societies, in the Reports of H.M. Inspectors of Mines, and in that of the Royal Commission on Accidents in Mines. There is great variety in the extent of these outbursts and in the force of the escaping gas. Cases are on record in which a mass of 1 1 tons of coal has been violently projected into the workings by the escape of the gas, and in which considerably more than a million cubic feet of gas have been given off, whilst it is also recorded that the blower at Garswood HaU Colliery has furnished a supply of gas for over nine years, and that the gas being led to the surface by pipes and there ignited has given sufficient light for the carrying on of the colliery work at night. The American gas wells (referred to further on under " Natural Gas ") are probably due to similar collections of fire-damp, although on a much larger scale. The maximum tension of the gas confined by water in a limited space of mine, was estimated by one of the leading engineers of the north, Mr. T. J. Taylor, in an experiment made in the Bensham seam, at Percy Main, at 4^ atmospheres ; but it required some time to attain this elastic force. A pressure of 4^ atmospheres would fully account for the forcible disruptions which accumulations of gas sometimes produce ; but the difficulty still remains of conceiving in what condition the gas can be distributed through the entire coal formation. The pressure at which gas exists in coal, or at which it escapes, has been frequently observed, and of recent years measure- ments have been made of the pressures developed in cavities bored in different seams of coal in England and South Wales. The pressures of escaping gas at Pelton Colliery were in 1 844 * esti- mated at 67.5 lbs. per square inch and 912 lbs. per square inch, or sixty-two atmospheres ; t and in the measurements carried out by the Royal Commis- sion on Accidents in Mines J pressures of 200 lbs., 461 lbs., 430 lbs., and 318 lbs. per square inch have been observed. Holes were bored in different seams of coal at depths varying from 750 feet to over 2,000 feet below the surface, and the accumulated pressure of gas was observed every hour by gauges. The rate of outflow of the gas was also observed, but it was noticed that the indicated volume of escaping gas bore no relation to the pressure, whilst the pressure appeared to be extremely variable, even in the same seam. The specific gravities of the various gases entering into the mixture called fire-damp, are as follows : — * "Trans. N. of E. Inst. M.E.," vol. iii. p. 38. t Ihid,, vol. xxx. J " Final Eeport Eoy. Oom. on Aoc. in Mines," pp. 20, 21. COMPOSITION OF FIKE-DAMP. 69 Air 1. 0000 Marsh gas or methane . , . 0.5596 Hydrogen 0.0692 Olefiant gas or ethylene . . 0.9784 Sulphuretted hydrogen . . . 1.1912 Carbonic acid . . . 1.5290 Nitrogen 0.97 1 3 Oxygen . 1.1056 In the mines, the law of diffusion does not in all cases come into practical operation, and the lighter gases are found occupying the upper portion of the galleries and workings, while the carbonic acid may be noticed creeping along the surface as the gases leave the goaf of some pits. Of these gases, the hydrogen is the most inflammable ; when mixed with two or three times its volume of air, it ignites at a temperature just below visible redness, and the flame thus produced will at once ignite the less inflammable gases when mixed in certain proportions with air. It has, however, been rarely detected in fire-damp. Olefiant gas, discovered by Bischof in the mines of Belgium, is also very infiammable, being ignited at a low red heat. It requires 15 volumes of air for complete combustion, and produces twice its own volume of carbonic acid, leaving 12 volumes of nitrogen to mix with the after- or choke-damp. This gas has not been generally found in the mines of this country. Sulphuretted hydrogen is also very inflammable, and is itself a poisonous gas : it seldom occurs in appreciable quantities in the mines of Great Britain, although the pyrites from which it is derived abounds in some districts of the coal fields. Marsh gas, which constitutes by far the largest ingredient of fire-damp, is not nearly so inflammable as the other combustible gases. It requires about 10 times its volume of air for complete combustion, and produces its own -volume of carbonic acid, leaving 8 volumes of nitrogen from the air. Ignition is only produced in this mixture by a white heat, but is instanta- neous in contact with flame. The former fact, in connection with the cooling effect of wire gauze, led Davy to the discovery of the lamp which bears his name, and is the parent of the many existing varieties of miner's safety lamp. These gases, particularly the last, ever issuing from the fissures of the > innammable. I ,, 16 ,, gave a voluminous, waving, spindle-shaped pale blue cap, 3I inches high. I ,, 18 ,, a similar cap 2 inches high, which burned rather more steadily. I „ 20 ,, a cap of i^j; inch high, cap perfectly steady and more distinct than any of the others, a conical cap ^ inch to | inch high, a conical cap f inch high, a conical cap y\ to J inch high, an exceedingly faint cap ^ inch high, the top having the appearance of having been broken off. I ,, 60 ,, it was hardly possible to distinguish anything above the small oil flame. The experiments of Kreischer and Winkler have the effect of throwing some doubt on the accuracy of Galloway's numerical results, but they also show that the height of the cap varies considerably, for the same mixture of air and marsh gas, with the form of the lamp and with the nature of the illuminant used. They employed five different safety lamps, I 3) 25 I 30 I ,, 40 I ,, 5° 72 PIELER'S INDICATOR. Fio. II. two burning benzene, two burning rape oil and one burning a mixture of rape oil and petroleum. The British Eoyal Commissioners say of these experiments that " they show that, if the air contains i per cent, of gas the reduced flame ex- hibits only the faintest traces of a cap when the iUuminant is benzene or a mixture of rape oil and petroleum, while with rape oil alone even these traces disappear. When 2 per cent, of gas is present in the air, the cap may be distinctly seen on the flame of a benzene lamp, almost as distinctly on the flame produced by mixed rape oil and petroleum, but less distinctly on the flame of rape oU." The safety lamp which is ordinarily used in Britain in searching for fire-damp is proved to be not only inferior to other forms of safety lamps as an indicatdr of gas, but also unable to give any indication of an atmospheric condition which, ii combined with the presence of coal-dust, is one of considerable danger. This fact, as well as the possible introduction of electric miner's lamps, which cannot give any indication of gas, has given increased importance to other methods which have been devised for de- tecting fire-damp in smaller quantities than have usually been searched for. Of these the lamp of Herr Pieler is regarded with some favour in Germany. It is shown in the illustration. Fig. 11, which is (with Figs. 12-16) copied by permission of the Council from the " Transactions of the Mining Institute of Scotland " (vol. viii. part 3). It is a lamp of the Davy pattern, but constructed to burn alcohol with an argand burner, the tube supplying air to the inner surface of the flame passing vertically through the vessel containing the spirit and being protected by discs of gauze. A small conical chim- ney about an inch high surrounds the flame, which is regulated by a screw, so that in pure air no flame appears above the chimney. All the cap that is seen above the cone is therefore due to gas. This is said to be a very sensitive gas detector, as small a quantity as 5 per cent, showing a cap 1 3 inch high, while i per cent, gives a sharply defined cap of 3 inches long. In order to protect this lamp in the currents of well-ventilated mines, and to prevent it com- municating flame to the outside of the gauze, it requires, as the British Commission pointed out, to be enclosed in a case. An excellent description of the various methods which have been proposed is contained in the Final Eeport* of the Boyal Commission on Accidents in Mines, and it is unnecessary to enumerate them. The most iBi — '' 1 — m ,L 3 »ii...T.iaiiii» |g * Eeferalsoto "Trans. Manchester Geol. Soc," vol. xvii. ; "Mining Inst. Scot.," vols. i. ii. and viii.; "N. of Bug. Inst. M.E.," vols. xv. xx^x.; "Chesterfield and Midland Inst. Eng.," vol. xiv. ; "S. Wales Inst, of Eng."; Annates des Mines, 2nd scr. tome xix. pp. 186-211; Archives des Sciences Physiques et Naiurelles, Geneva, 3rd ser. vol. v. (1881) ; Bull, de la Soc, de Vlndus. Min,, 2nd ser. vol. vi. ; " Jour. Iron and yteel Inst." FIRE-DAMP INDICATOES. 73 notable of them are founded either on chemical or on physical reactions — those making use of chemical reactions operating by causing the combustion of a small quantity of fire-damp in a closed vessel and measuring the resulting contraction of volume. The reaction is as follows : CH, -t- 20^ = zH^O -t- CO^ in volumes 2442 If the water formed is wholly condensed, the contraction is equal to double the volume of the fire-damp consumed ; where the carbonic acid is also absorbed by potash to treble its volume. Fig. 1 2 shows diagramatically the principal elements of such instruments. " The receiver is fitted with a rubber cork through which passes, air-tight, a glass tube of small diameter and two conductors or electrodes, connected at the top by a spiral of platinum. When we connect the conductors to the accumulator, the current Fig. 13. Fig. 12 passing is sufficient to raise the platinum coil to a white heat. This in- creases the temperature of the air in the receiver, and would force some of it out, but there is a rubber cork in the foot of the glass tube to prevent this. If we wait till the temperature falls and take out the cork, it will be seen that the' water does not rise in the tube. If we now take ofi" the receiver and introduce into it the sUghtest quantity of coal gas-;— not too much, or we will have an explosion — then pass the current for a second or two, so as to raise the coil to incandescence, allow the receiver to cool, and take out the rubber cork from the foot of the tube, we shall find that the coloured water rises a considerable distance up the stem."* The instruments of Coquillon and of Maurice are founded upon this action, that of Maurice being shown in section in Fig. 13. The reservoir is if inch diameter and 7 inches high, and the diminution of pressure due to the contraction after combustion is measured by the expansion of air contained in the bulb within the receiver. Graham's law of the diffusion of gases, according to which it has been found that " gases diffuse or intermingle with one another at velocities in- versely proportional to the square roots of their densities," has been made use " Mr. J. Gemmell in " Trans. Min. Inst, of Scot," vol. viii. 74 EIRE-DAMP rNDICATOES. Fio. 15. Fio, of in Ansell's indicator, and in a more recent one by Emmott and AckrQjrd. Fig. T4 explains the principle on which they are founded. One end of the tube rests in a vessel containing coloured water, and the other end is closed by a stopper of stucco or some other porous substance. If the tube be filled . with coal gas, and the stopper inserted, the coal gas will diffuse through the stucco faster than air enters the tube, and conse- quently there will be a diminution of pressure in the tube which may be registered or otherwise made use of. In Ansell's indicator (Fig. 15), this diminution of pressure is recorded by means of an index of the kind used in aneroid barometers. In Emmott and Ackroyd's* indicator, two incandescent electric lamps are used — one having clear glass and the other a red- coloured bulb — and the circuit is so ar- ranged that in an ordinary atmosphere the colourless lamp alone shines, whilst in fire- damp this one goes out and the red one is illuminated. This action is produced by the movement of a mercury contact occupy- ing the lower portion of a curved tube, one end of which is open and the other connected with a porous pot of unglazed porcelain, the motion of the mercury being due to the increased pressure in the porous pot occasioned by diffusion. One of the most important of these indicators is that of Liveing, which utilizes the increased brilliancy of the light given off by a heated platinum wire in contact with fire-damp. This brilliancy is due to combustion of the fire-damp taking place at the surface of the wire and imparting heat to it, and it is compared with the light emitted from a platinum wire heated in pure air. Fig. 16 roughly illustrates the action of this instrument. In a box are fitted two spirals of platinum, one being sealed in a glass tube containing pure air and the other being exposed to the air of the mine (in the illustration to a source of coal gas). A movable screen between them, such as is used in photometric observations, enables the difference of light to be measured by a scale showing the position of the screen. This instrument .has been combined with a portable electric miner's lamp by Mr. J. W. Swan,t who has also adapted an indicator on Maurice's plan to his lamp. The effect of the presence of carbon dioxide on the phenomena exhibited by fire-damp indicators is not yet clearly understood. M. CastelJ has investigated the action of Coquillon's " Grisoumfetre," and has given formulae for calculating the amount of contraction with different mixtures of gases and different temperatures in the palladium or platinum wire. Messrs. Fig, Trans. Phys. Soc," vol. viii. pp. 60-71. t See^' Trans. N.of Englaod Inst. M.E.," vol. xxxi. p. " Irans. Phil, Soc. Glasgow," vol. xvii. p. 151 117, XXXV. p. 51, and xxxvi. p. 3, t Annates des Mines, 1881, p. Kpg. COAL-DUST AND EXPLOSIONS IN MINES. 75 Mallard and Le Chatelier have also acquired indirectly some information bearing on this point, in the course of their experiments on the tempera- ture of ignition of gaseous mixtures.* They used a closed chamber, heated externally, and introduced various mixtures of gases after the chamber had previously been exhausted. The gases investigated consisted of explosive mixtures of hydrogen and oxygen, carbon monoxide and oxygen, and fire- damp and oxygen ; and the ignition temperatures obtained for these mixT tures were respectively 555° 0. (1031° F.), 655° 0. (1211° F.), and 650° C. (1202° F.). These results were found to be independent both of the presence of an inert gas such as nitrogen, or of the proportions in which the explosive gases were mixed. It was noticed, however, as an exception, that the addition of a large quantity of CO^ elevated the ignition temperature of a mixture of CO. and O from 655° 0. to 700" 0. (1292° F.). For mixtures of H and CO with 0, combustion ensued immediately on exposure to the temperature of ignition. In the case of fire-damp and oxygen, however, it was remarkable that ignition did not occur often till ten seconds after the mixture had been raised to or above the temperature of Ignition. t This retardation of ignition may be the result of indirect combination. Coal Dust. — The credit of being the first to direct attention to the dangerous nature of coal-dust seems to be divided between Robert Bald,J " the acknowledged father of mining engineering in Scotland," and J. Buddle,§ the famous North-country viewer, " who was the chief of the Newcastle coal-miners for nearly the first half of this century." Bald pointed out, in " Jameson's Journal"for 1828, the possibility of the ignition, by the flame of fire-damp, of the dust which was to be found in or near the working places of a co&,l-pit ; while Buddie recorded the efiects of dust in an explosion which occurred in September 1803, in theWallsend Colliery. Some notice of coal-dust accompanying and aggravating an explosion of •fire-damp at Felling Collieries |( in 18 12 was also published, but the subject remained in practical obscurity until Faraday and Lyell^f published, in 1845, their report to the Home Secretary on the explosion which took place at Haswell Collieries in September 1844. This report is notable from its throwing the first clear and unmistakable light on the subject, and demon- strating the method in which action proceeds in a dusty mine when an explosion of fire-damp occurs. The following is quoted by the JRoyal Com- missioners from it : — " In considering the extent of the fire from the moment of the explosion, it is not to be supposed that fire-damp was its only fuel. The coal-dust swept by the rush of wind and flame from the floor, roof, and walls of the works would instantly take fire and burn if there were oxygen enough present in the air to support its combustion ; and we found the dust adhering to the faces of the' pillars, props, and walls in the direction of, and on the side towards, the explosion, increasing gradually to a certain distance as we neared the place of ignition. This deposit was in some parts half an inch, in others almost an inch, thick ; it adhered together in a friable, coked state. When examined with the glass, it pre- sented the fused round form of burnt coal-dust, and when examined chemi- CiiUy and compared with the coal itself, reduced to powder, was fotmd » Annates dm Mines, yol. iv. 1883, pp. 274, 379-559. t See also Berthelot and Vieille, Compt. liemins, xct. pp. 151- 157 ; " Trans. N. of Eng. Inst. M.E.," vols. xxxi. p. 8, xxxii. pp. 12, 13. J J. Gemmell, in "Trans. Min. Inst. Scot.," vol. viii. p. 99. 5 "Eeport Koy. Com. on Accid. in Mines," 1886. |i "Trans. Chesterfield and Derbyshire Inst. M.E.," vol. x,; "Fossil Fuel, Collieries and the Coal Tr.ade." H "Koy. Com. Report ;" " Trans. Ohes. and Derb. Inst.," vol. jt. ; " Phil. Mag.," 1S45. 76 COAL-DUST AND EXPLOSIONS IN MINES. deprived of the greater portion of the hitumen, and in some instances entirely destitute of it. There is every reason to i)elieve that much coal gas was made from this dust in the very air itself of the mine by the flame of the fire-damp which raised it and swept it along, and that much of the carbon of this dust remained unburnt only from want of air. At first we were greatly embarrassed by the circumstance of the large number of deaths from choke-damp, and in the evidence that tliat had been present in very considerable quantities compared with the small proportion of fire- damp, which, in the opinion of those in and about the works just before, must have occasioned the explosion. But on consideration of the character of the goaves as reservoirs for gaseous fuel, and tlie effect of dust in the mine, we are satisfied that these circumstances fully account for the apparent discrepancy." The fact that the deposit of " dust " accumulated towards the explosion above referred to can by no means be wholly explained by the supposition that it was purely coal dust. A mixture of marsh gas or fresh fire-damp with gas already exploded, or after-damp, might very well locally occur, and in certain proportions would give rise to a deposition of carbon : — It should be observed that a fine sooty deposit — much more resembling synthetic carbon than coal-dust — has in several cases been observed after explosions in mines. Faraday also lectured at the Royal Institution on this subject in January 1845, and by this means gave greater publicity to it, but never- theless little attention seems to have been directed to it until recently. The Reports of H.M. Inspectors of Mines mention the eifects of coal-dust in connection with the explosions at Ince Hall in 1853, Wynnstay in 1873, Silverdale in 1876, Blantyre in 1877 and 1879, and Penygraig and Lycettin 1880; whilst in the "Transactions" of the Royal Society, the Manchester Geological Society, the North of England, the North Stafford- shire and the Chesterfield and Derbyshire Institutes of Engineers the real investigation of the matter belongs to the last ten years.* In France, the subject appears,, according to the British Roj'al Commis- sioners, to have " remained long unknown, for in 1855 M. du Souich, Chief Government Mining Engineer of the St. Etienne Arrondissement, when referring to an explosion which had occurred at Firminy, advanced as new the view that the deposition of crusts of a light coke upon the props was due to dust which had been swept up and transported to a distance by the violent current produced by the explosion, and which, becoming in part inflamed, had extended and prolonged the destructive effects originated by the flre-damp. On the occasion of two explosions in 1861, M. du Souich again dwelt on his views regarding the part played by coal dust in increasing the disastrous effects of fire-damp explosions." In 1864 M. Verpilleux published t his ideas on the subject, and in 1864-67 he carried out some experiments which substantiated the view that coal-dust plays an important part in coal-mine explosions. Several other French mining engineers carefully investigated the matter, and the records of their work and discussions thereon will be found in the Annates des Mines and in the Bulletin de la 8ociete de V Industrie Minerale-X ^^ particular, M. Vital carried out experiments in 1875 in connection with " an inquiry into an explosion which had occurred the year before in a part * See also " Explosions in Coal Mines," by W. N. and J. B. Atkinson (London : Longmans, t Bulletin de la Soc. de VIndm. Miiiirale de St. Etienne, tome ix. p. 468 : also ibid. vol. for 1875; "Iron," vol. for 1878. r t , % See also Report by M. Haton de la Goupillifere on this subject, 1878. COAL-DUST AND EXPLOSIONS IN MINES. •]•] of the Campagnac Colliery where the existence of fire-damp had never been demonstrated. After examining the nature of the dust collected in the mine and instituting some special experiments, though on a very small scale, for the purpose of ascertaining whether, and to what extent, the flame from a small charge of powder was lengthened when projected, like the flame from a blown-out shot, into air containing coal-dust in suspension, M. Vital concluded that very fine coal dust, rich in inflammable constituents, will take fire when raised by an explosion, and that portions are successively decomposed yielding explosive mixtures with air, whereby the fire is carried along, the intensity or violence of the burning being much influenced by the physical characters of the dust." In Britain, the subject has been investigated with great care and in a thorough mariner by means of experiments on a much larger scale than those mentioned, principally by Messrs. W. Galloway* and Hall and Clarkf in. 1876, Marreco and MorrisonJ in 1878, Sir F. Abel and the Royal Commissioners in 1880— 1886, and the Committee of the Chesterfield and Derbyshire Institute of Engineers in 1880— 1882. There have been also, in recent years, Commissions appointed in France, Belgium and Prussia for the investigation of this subject and that of fire-damp, and the experiments carried out by the last-nam.ed were of a very complete and important character. The first conclusion arrived at by Vital and Marreco was that fiame could be propagated with explosive eifects by coal-dust alone in the absence of fire-damp. This accords with the fact that coal-dust has been used as a rapid combustible and also as fuel for furnaces. As to the former, a work by Borgnais published § in 1818 gives, according to a report to the Institute of IVance by BerthoUet and Carnot, a description of an engine worked by the rapid combustion of fine dust, in a manner somewhat similar to that of the gas engine. The dust used at first was composed of lycopodium, but the engine was found to work equally well with coal-dust mixed, according to need, with a little resin. In furnaces, coal-dust has been used successfully by Whelpley and Storer in America, and Crampton, Ferret and others in Britain, the fine powder being simply blown into a combustion chamber by air, where it is ignited and burns. The combustible nature of other fine dusts has been frequently proved, as, for instance, by explosions in flour mills, several of these having occurred in America, and one notable one at Tradeston Mills, in Glasgow, which was investigated and reported upon by Professors Macquorn Rankine and Macadam. The general impression amongst H.M. Inspectors of Mines, however, as witnessed to by the evidence they gave before the Royal Commission, was that coal-dust might aggravate explosions which were caused initially by fire-damp, but that explosions could not be originated or propagated by coal-dust alone. Even Mr. W. Galloway seems to have inclined to that belief at one time, and Messrs. Mallard and Le Chatelier, in France, an- nounced it as the only rational one. It has, however, been conclusively proved to be short of the truth, and the later experiments of Mr. W. Galloway, Sir F. Abel, and the Prussian Commission have set the matter at rest. Mr. Hall's experiment, which was the first practical experiment with • "Proc. Eoy. Soc," 1876-84; "Brit. Assoc. Eeports," 18B1. \ " Trans. N. of Eng. Inst. M. Engineers," vols. xxv. p. 239, xxvi. p. 101. t Ibid. vol. xxviii. pp. 85, 156 ; " Trans. Chesterfield and Derbyshire Inst. M.E, ," vol. v, p. 267, vi. pp. 49, 244, 290, vol. X. § " Traite oomplet de mfecanique appliqufe aux arts ; composition des machines, p. 197. 78 COAL-DUST AND EXPLOSIONS IN MINES. coal-dust known to have been carried out, did not give conclusive proof, as it was not certain that fire-damp was absent. It was made in a brick- arched mine 45 yards long and 30 feet area driven from the surface. When a 2^ -lb. shot stemmed with small stones was fired, the flame extended only to 1 5 feet ; but when coal-dust was scattered on deals (the pavement being wet) over the whole length of the adit, and a similar shot stemmed with small coal was fired, the flame extended along the whole length of the mine and issued from the mouth in a large volume, and with a fierce blast which would have been fatal to any one exposed to it. The investigations of the British Royal Commission dealt with a great variety of conditions. " Experiments were made in the first instance with a view of ascertaining the smallest proportion of fire-damp which, when mixed with £ta air current, would furnish an atmosphere capable of firing at a naked flame of a par- ticular size placed in the experimental gallery. It was next ascertained- what quantity of gas below that proportion was needed to impart to the mixture of air with a large quantity of each particular coal-dust experi- mented with, the property of exploding throughout the gallery. By these experiments, the samples of coal-dust were classed in the order of their sensitiveness to explosion, and it was found that, while those which were very rich in pure coal, and which contained the highest proportion of very fine dust, required the lowest proportion of fire-damp in air to bring them to explode readily when suspended in a dense cloud, the order of sensitive- ness of samples containing higher proportions of non-combustible matter did not necessarily harmonize with their comparative richness in pure coal nor with their comparative fineness. This was strikingly illustrated by two samples of dust from Seaham Colliery ; one of these, taken from the roads, contained more than half its weight of non-combustible matter, yet ranked third in order of sensitiveness ; another, which contained considerably more coal and a somewhat larger proportion of the finer dust, ranked only fifth. " Another point clearly established, and confirming by more accurate data the observations of earlier experimenters, was that the proportion of fire- damp required in a mine to bring dust readily into operation as an explosive material when thickly suspended in the air, borders on, and is even some- times below, the smallest amount which can be detected in the atmosphere of a mine by the most practised observer with the use of a Davy lamp. Explosions were produced by dust suspended in air travelling at a velocity of 600 feet per minute when fire-damp was present in proportions of 2 to 2.75 per cent.; in currents of low velocity, the same result was produced with a sensitive dust in the presence of only 1.5 per cent, of fire-damp; ignitions which approached explosions in their nature and extended to considerable distances were, moreover, obtained with this dust in air containing still smaller proportions of gas. " Mixtures of fire-damp and air bordering on those which would ignite on the approach of flame were found to be instantaneously fired by a lamp if they contained only a few particles of dust in suspension, and in connection with this fact the interesting o'bservation was made that such dust particles need not be inflammable or combustible to produce the result named. Mixtures of air and gas which passed a naked flame without any symptom of ignition, were inflamed when particles of a fine, very light powder, such as calcined magnesia, were suspended in them. The action of certain of the pit dusts which contained comparatively little coal, in determining the ignition of mixtures of air and small proportions of fire-damp, was possibly of the same character as that of the calcined magnesia. The power of favouring the ignition of mixtures of fire-damp and air was not exhibited by some other powders similar in fineness to the latter, but differing in COAL-DUST AND EXPLOSIONS IN MINES. 79 structure and density from this and one or two other non-combustible dusts which may be called active ; even different samples of magriesia differing somewhat in lightness from each other, appeared to possess the activity in different degrees. These facts seem to favour the view that a dust which possesses peculiar physical characteristics exerts a contact or catalytic action on gas mixtures, similar to that known to be possessed by platinum and some other substances under particular conditions. Thus, when finely divided platinum, or even a clean, recently heated surface of the compact metal, is brought into contact with mixtures of hydrogen or of hydrocarbon gas or vapour, with oxygen or air, oxidation of the hydrogen or the hydro- carbon is at once established, and proceeds at a rapidly accelerating rate, as the chemical activity is promoted by the accumulating heat, so that the metal is speedily raised to a temperature sufficiently high to bring the sur- rounding gas mixture to the exploding point. " In many of the experiments with calcined magnesia, it was distinctly noticed that a dark space intervened between the gas flame used as the source of heat and the flare produced by the ignition of the gas mixture through the influence of the dust-cloud suspended in it ; this would seem to indicate that the dust particles, immediately after passing through the flame, establish some amount of oxidation of the fire-damp, which proceeds with increased rapidity as the dust becomes more highly heated through the chemical action developed, so that, within a short distance from the point where the heating commences, the dust becomes incandescent and the ignition of the gas mixture follows. There appears little doubt that this action of non-combustible dust in promoting the ignition of gas mixtures which, in the absence of diist, are not susceptible of ignition by the volume of flame or highly heated matter projected by a blown-out shot, constitutes one element in the dangers arising from the presence of dust in the air of a mine which contains a small proportion of fire-damp, and in which a large body of flame is accidentally produced, either by a powerful blown-out shot, or by a fire-damp explosion of local character." The power of coal-dust in air, but in the complete absence 0/ fire-damp, to convey or to propagate flame, has been carefully inquired into by several experimenters, who have tried several sources of flame. A naked gas flame and shots from pistols and from small cannon were used in the ex- periments of Marreco and Morrison and of the Chesterfield Institute. Cannon were also used in the experiments of the British and Prussian Commissions, and, in the former, freely exposed heaps of gun-cotton and of slow and quick-burning gunpowder were also exploded in the dust-laden air. The general result of these experiments is, that with air-currents having a velocity of 200 and 300 feet per minute the volume of flame was decidedly increased when the dust-cloud was passing, but when the velocity of the current carrying the dust-cloud wa^ increased to 1,000 feet per minute the increase of volume of flame was more marked, although usually only a flare, and not an explosion, was produced. The tendency of the coal-dust flame seemed to be to travel in the direction of the current and not so much against it as was the case with flame produced when dust was absent. The British Commissioners say that the most decisive of their results were not of a nature to warrant the conclusion that flame could be carried along to very great distances by coal-dust in the complete absence of fire-damp. Investigation of the effect of blown-out shots in igniting dust, and of the distance to which any burning effect from a blown-out charge of gun- powder would extend in a mine working in the absence of coal-dust, showed that " cannon when fired into air currents of 100 to 200 feet velocity con- taining 2 J per cent, of fire-damp, and i"nto a current of 300 feet velocity 80 COAL-DUST AND EXPLOSIONS IN MINES. containing 3I per cent, of fire-damp, produced no effect. "When discharged into a current containing only if per cent, of gas at a velocity of 100 feet per minute, with coal-dust thickly suspended in it, the portion of the gallery in front of the flash was filled with flame ; and with 2 to 2 J per cent, of fire-damp the gas and coal-dust mixture fired with explosive effect." It was proved also that while the flame from charges of i^ lb. to 2 lbs. of gunpowder, tamped and untamped, extended to from 20 to 35 feet when dust was absent, in the presence of dust the flame extended to from 37 to 83 feet, according to the velocity of the current and the dryness of the air. In a countermine gallery 81 feet long, open at both ends, and inter- ' sected at right angles by another gallery at a distance of 70 feet from the cannon or shot-hole, charges of 3 lbs. of powder untamped were fired, and coal-dust was blown into the air about 50 feet in the rear of the gun, a current of 70 feet per minute passing from the main into the left branch of the cross gallery. The following results were obtained : — Length of Flame in Feet. Main Gallery. Left Gallery. Right Gallery. With slight quantity of dust . „ greater „ „ . „ still greater quantity of dust n )j J) )j 50 70 81 81 6 12 18 3 The Prussian Commission,* while confirming in several respects the results obtained by other investigators, and especially corroborating the conclusions of the British experimenters as to the influence of coal-dust on non-explosive mixtures of fire-damp and air, have added the following re- sults : — EXPERIMENTS MADE TO ASCERTAIN THE ADDITIONAL LENGTH GIVEN BY COAL DUST TAMPING TO THE FLAME FROM A BLOWN-OUT SHOT. Powder Charge. Ounces. Length of Flame. With Clay Tamping. With Tamping of Coal-dust of Medium Inflammability. 7-4 18. 9 ft. 10 ins. to 13 ft. 13 ft. 29 ft. 6 ins. to 52 ft. 6 ins. 62 ft. Experiments t made on the power of blown-out shots to raise and in- flame dust, I lb. of dust per running foot was laid on the floor of the gallery for 33 feet from the shots. Charge 7.4 oz. of powder fired from cannon near floor Length of Flame. With very fine dusts . . 69 to 102 feet ,1 fine dusts . . . 43 „ 69 ., ,, medium dusts . . . . 39 n 49 n „ coarse dusts ... . 20 „ 39 „ „ anthracite dust (dust tamping) . 26 „ 30 „ With inflammable dusts, clay and coal-dust tamping gave the same results. With less inflammable dusts, however, the flame was considerably extended by coal-dust tamping. While, with coarse dusts of low inflammability, the flame could not be got to reach beyond 39 feet, however far in advance the dust might be ' See translation of Report, by T. W. Bnnning, in " Trans. N. of E. Inst. M.E.," vol. xxxiv. f J. Gemmell in " Trans. Miu. Inst. Scotland," vol. viii. p. 106. PRUSSIAN EXPERIMENTS ON COAL-DUST. 8 1 strewn, with two very fine and highly inflammable dusts, the flame continu- ally increased as the strewing was extended, until, with 130 feet of the floor laid with them, the flame was projected 16 feet outside the mouth of the gallery — that is, it had a total length of 183 feet. Violent explosions resulted with either of these dusts when they were strewed in excess of 66 feet, and columns of flame from 3 to 6 feet in height, followed by dense black smoke, escaped from the vent-holes of the gallery. Mr. W. Galloway in his remarks on these results, in a discussion* on them in this country, said that it should be strongly insisted on that Pluto dust (which was one of the two inflammable dusts referred to in the foregoing) created a true explosion. The Eeport of the Prussian experi- ments made by Mr. Hilt of Aachen, stated that the effect of all the experi- ments with Pluto dust was to show that, however long the gallery might be, supposing the dust to be strewn equally far along it, the flame would pass along its whole length. Mr. W. T. Lewis (one of the British Commis- sioners) and Mr. Galloway witnessed some of the experiments in Germany, and wishing to see the utmost that dust could do, the experimenters strewed a greater length than usual in the gallery to show them, the distance strewn being from 131 to 164 feet. When the shot was fired, there was a practically instantaneous explosion, such as would be produced by gas. " There was a very loud noise, like the firing of a great cannon, the flame came out of the mouths of the safety valves and flew high into the air, and the after-damp filled the whole space over the pit-heap. A waggon, loaded so as to weigh 14 cwt., was driven 52 feet along the rail- way, rising at an angle of 4 degrees ; it then left the rails and ran a further distance of 6 feet on the ground. The end of the waggon, next the ex- plosion, was broken, the boards being actually staved in. There was a small baulk, about 4 inches square, placed across the rails and bolted to keep the waggon from running into the gallery ; this baulk was torn away from the bolts and thrown to a great distance over the pit-heap. The brattice, about i J inch thick, which was placed at the end of the branch gallery, was completely torn out and broken up." The German experi- menters found that Pluto and Neu-Iserlohn dust were equally capable of causing an explosion, but they concluded from their trials, although some- what hastily, in Mr. Galloway's opinion, that other dusts were compara- tively harmless. Mr. Galloway points out that when a colliery explosion has been started, by whatever means, there is a blast of air produced through the mine which raises the dust — coarse and fine together — in a whirlwind. The flame passing along can ignite the fine dust, and if there is a large proportion of coarse particles in the cloud the flame does not travel so fast as when only fine dust is there, but it passes through and ignites the dust in one case as in the other, only delayed a little by coarse particles. The Prussian experiments were carried out in an elliptical main gallery 167 feet long, 5 feet 7 inches high, and 3 feet 11 inches wide, closed by brickwork at the £ring end, but open at the other. At 93 feet from the closed end, a branch gallery 33 feet long left the main gallery at right angles, and was closed by a door having safety valves in it. Seven cast-iron cannon were built into the brickwork, the centre one being 1.57 inch diameter and 37 inches long, and the others 1.38 inch diameter and 31^ inches long, and all pointed to a spot in the axis of the gallery which was 16 feet 5 inches in front of the face of the brickwork. At the opening of the gallery, and in line with it, an ordinary mine railway was laid to some distance on an incline of 4 degrees, or about i in 14, * " Trans. N. of E. Inst. M.E.," vol. xxxiv. p. 253. 82 CASES OCCLUDED IN GOAL. and on this a truck loaded with iron was placed, its propulsion frdm the mouth of the gallery furnishing a rough indication of the force developed by the explosion in the gallery. The following table shows the results of experiments made on the elonga- tion of a flame from a blown-out shot produced by coal-dust stemming when fired into gas mixtures : — Dust from the Konig Pit. Dust from Neu-Iserlohn. Percentage of Gas; Length of Flame. Feet. Distance Truck blown along Railway. Feet. Speed of Flame. Length of Flame. Feet. Distance Truck blown along Railwar. Feet. o I 2 3 4 1 45-9 49.2 52- S 65.6 82.0 1 14. 8 134-5 2.29 2-95 3.28 4.10 7.60 10.80 45-90 One yard J per second Like lightning Explosion 49.2 62.3 78.7 95-1 101.7 1 18. 1 154.2 2.60 3-93 4.92 7.21 8.52 II. 10 23 to 32.8 Tub much damaged. It is also held to have been proved by the German experiments that a fire-damp mixture some distance from a blown-out shot can be fired by the flame transmitted by coal-dust ; that a mixture containing 7 per cent, of gas with air in the main gallery, exploded by a blown-out shot, exploded coal- dust in the branch gallery, although there was an intervening space of 56 feet altogether free from gas and coal-dust; and that flame produced by the ignition of coal-dust in the main gallery produced an explosion of coal- dust in the branch gallery, although there was an intervening space of 26 feet clear of coal-dust. The prevention of accidents and disasters from these causes is a matter of the greatest importance in the working of coal, and the fuel industry must be considerably affected in future by the means adopted to secure safety. These would seem to be limited either to the removal of dust, or its being rendered innocuous in presence of flame, or to the discovery of means for the prevention of blown-out shots in blasting, or to the modification of explosives or methods of using them so that escaping fiame or sparks will be prevented, or to methods of working free from the dangers attending the use of explosives. Gases Occluded in Coal. — In almost all coal, there is a quantity of gas which is held mechanically suspended throughout the mass. It is difiused through the pores of the mineral, and may be collected in larger quantities in crevices or cavities, from which as previously mentioned it frequently escapes during mining operations with some violence, thus show- ing that it has been retained under considerable pressure. Explosions of " fire-damp " and fires in coal-mines are, in many instances, due to this cause, and even after coal has been mined, the continued escape of this " occluded " gas is a source of danger, and is accompanied by deterioration of the quality of the coal. The disastrous explosions which have occurred in vessels carrying coal cargoes, and in the coal-bunkers of steamers, have been traced to this action, and the presence of the gas, even where there is not a sufficient quantity to cause an explosion, greatly adds to the dangers of spontaneous ignition in such circumstances. Many examinations of the composition of the occluded gas have been made bv E. v. Meyer, and his results are collected in the tables given on pp. 84, 85, "which were published by Dr. Percy ("Metallurgy"), SPONTANEOUS IGNITION OP COAL. 83 These tables reveal the inflammable nature of the gas which is given off from freshly mined coal, and they also throw light on the action of the air on coal which is exposed to it for any length of time. This action is termed "weathering," and consists mainly in the combination of the carbon and hydrogen of the coal with the oxygen of the air, carbonic acid and water being formed, while the proportion of disposable hydrogen is reduced. When pyrites is present, it is also oxidized, especially in presence of moisture, and moderate elevation of temperature accelerates the action. The oxidation of pyrites when present in considerable quantity causes the disintegration of the coal, sometimes to such an extent as to render it nearly worthless. It will be understood from this that the calorific power of the coal — that is, its practical value as fuel — is seriously impaired by exposure to air, and this may take place so rapidly that in some places coal is known to lose 50 per cent, of its heating value in six months. These actions may take place without the generation of any sensible heat ; but when coal is collected in heaps or in consideiable quantities in the holds or bunkers of vessels, oxidation may proceed so energetically as to cause a considerable elevation of the temperature of a part of the mass. This may also take place in the coal-pits, if any quantity of dust or fine slack is allowed to accumulate there, and the point of ignition is frequently reached, so that, in pits, coal cargoes, and in heaps, many serious fires have been known to break out. These dangers of the spontaneous ignition of coal have caused a large amount of attention to be turned to the investigation of the subject, in order that measures might be devised which would lessen the probability of disaster. It has been ascertained that the absorption of oxygen by fine coal, dust, or gum, without the presence of iron pyrites, may generate suflicient heat to cause self-ignition of the coal or of the gases given oflT; that, as soon as the temperature rises, oxidation proceeds more rapidly; and that the oxidation of pyrites, especially in presence of moisture, greatly adds to the danger.* The only method of preventing fires from such causes is to keep the temperature of the mass of coal as low as possible, by means of thorough ventilation by currents of air. Various other methods of treatment have been suggested, but none are feasible. It has been proposed to pack coal by hand in vessels in large lumps, to prevent the presence of small coal, but unless the coal were cut in regular cubes, the iiregularities of the lumps and the motion of the cargo caused by movements of the vessel would soon result in the manufacture of f^mall coal and even dust. This plan would, therefore, at best only delay the action, besides being open to other objec- tions on the score of cost of handling and of increasing the quantity of unmarketable small coal at the pits. It has also been proposed to seal up the coal hermetically in the holds of vessels, but that is impossible, as the hold of no ship is air-tight, and, moreover, the quantity of air distributed throughout such a mass as a cargo would be sufficient to start the action of oxidation. The lateT. Rowan, in " Spontaneous Combustion and Explosions occurring in Coal Cargoes," . ropo ro ■* 1 ON u-1 '^ ^d 1 s- i ^ S5 i-« CO =^ s m\o \o f3S, ??''§■ d d »-^ ? (g^^ M ag<3 00 « N On - & N ^M- M fO o roO N M M l~H M M « -a- o vo O NVO N OOO M3 i-c - UT* « O t^ O •-< I ! I . o To u eg 4) ■IB *T! ' ^n3 ' c -«J -s . <0 bo -M* *S ^^ *"« °a a, o " I O QPQ <1 l-lijjeliislg " " -^ ■ J d c d PM .. J; t H N o 1^ «8 fc a £S s^ i^ Nt3 5£; >> ^P^ COMPOSITION OF GAS OCCLUDED IN COAL. 85 vo r^u-ivo I KOOO NVD ONTi-0>J-lO \O00 '-' O ONNO f^CT* NN«f^'-'N'-'f^O mo fo t>*«00-■§)■ =i= ID . >) . ,— I a • c '"^ o ""S^ § S-S "^ § " 5 - .S '^ e^ '^ r3 > o t^ *^ t_ S a H OJ'^ 03*— "''^ m^ o ^ iz; (_^ fli H C>3 ta _£ X n IF » K c -< H K^ O hfi r F! -3 =fc Tn ^ to (D .fe SQ rS fl) 1— [ '^ ^ 5 X C'g g'S S^ S.^ Cl-.OQ &rt »* CQ o'Q d.{£; dE> ©£=< chJ o ^ s ^ 5 « E O) "^ TJ -+3 0) g J! s e ^> W 1^ ro 00 00 y3 ■. O ■* M o w O in g, S- On ^o z ^ =1 a a =^ ^ V ■5 t) PQ O o ;S O .2 m s o H t! > t> o W W t= b> •— I I— I 86 EFFECT OF HEAT ON FUEL. Mr. J. W. Thomas* has made some examinations of coal which have considerable interest in connection with this subject. Mr. Thomas found that coal, when heated in a vacuum at a temperature of ioo° 0. (212° F.), gave off an appreciable quantity of gas. When the coal was subjected to a prolonged joint action of the vacuum and heat, not only did the quantity of the products increase, but their quality appeared to vary as the action went on. Late in the action, volatile products came off which condensed to crystalline solids, showing that these hydrocarbons probably did not exist originally in the coal, but were products of the action. Some experiments referred to by the late Prof. Freire-Marrecof showed that, in air, a tem- perature of about 600° F. was required to produce appreciable decomposition of the coal; but Mr. Thomas's results show that reaction commences, although slowly, at a very much lower temperature than has been supposed. The following are some of Mr. Thomas's most recent results : — Sample of Coal. Gas Evolved by 100 Grms. at 100° C. in a Vacuum. .si S4 m So c* 1 Wigan cannel 5/3 seam 350 yds. deep >, » 3/2 „ 600 _ „ S90tch (Heywood) oarnel, Wilsontown „ (Lesmahagow) cannel Whitehill cannel shale, Lasswade "Whitby jet (finest quality) . 421.3 C.C. 350-6 „ 16.8 „ SS 7 ., ' SS-7 .. 30-2 „ 6.44 9 -OS 53-94 84-55 687s IO-93 80.69 77-19 7.80 2.67 1 C^s 1 1 0-91 J 86.90 8.12 5-96 46.06 14.54 28.58 2.17 EFFECT OF HEAT 03!f FTTEIi. As combinations of organic origin, the kinds of fuel which have here been described are more or less complex in constitution, and therefore offer but slight resistance to external modifying causes ; the different kinds of coal ■ are easily decomposed, and, like other chemical combinations, can only exist within certain limits of temperature, the limit being greater for simple than for complex bodies. These varieties of fuel are not volatile, the chemical equilibrium amongst their elements being destroyed by an increase of temperature long before volatilization can take place ; and the decomposition caused by heat is simply an overthrow of the existing arrangement of the elements, while an immediate re-arrangement ensues with the formation of new comp9unds capable of existing at the higher temperature. The nature of the new products is therefore mainly dependent on the temperature, and these must vary in quantity still more than in quality as the heat is in- creased or diminished. The admission or exclusion of air (oxygen) during the process will, of course, still further modify the result ; in the former case, the products are immediately subjected to the energetic chemical action of oxygen, with which their elements readily combine, and com- bustion ensues as a secondary process ; in the latter, where decomposition by heat is effected without access of air, the coal undergoes dry or destruc- tive distillation, as it is called. The products of this operation can be conveniently collected and studied, and the process demands particular attention, not only because it obtains in every instance of combustion, but also because it is instrumehtal in producing an important transformation of certain species' of . fuel. It would, indeed, be a very erroneous idea to suppose that the combustion of wood, coal, or other species of fuel was •' See "Journal of the Ohem. Soc," 1876, ii. 144. t "Trans. N. of Eng. Inst. M.E.," vol. xxvi pp. 35-37. EFFECT OF HEAT ON FUEL. 8/ simply the result of a direct union of atmospheric oxygen with their elements ; on the contrary, the heat produced by the burning of one portion causes the dry distillation of the internal parts nearest to it, before they are brought into contact with the air. When these are at length exposed, they begin to be acted on by the oxygen. In short, it is not the wood which we see burning when a billet is ignited, but the products of its decomposition by the agency of heat. The main points in this process of decomposition by heat in closed vessels (destructive distillation) are the following. From the moment in which the heat destroys the former state of equilibrium of the elements, three circumstances concur in regulating the formation of the new products. These are : first) the temperature ; second, the degree of chemical attraction among the elements, or compound groups thereof, increased by their being in the nascent state ; and third, their volatility. Hydrogen and oxygen possess the latter property in an eminent degree, whilst carbon is not volatile; there is a tendency, therefore, in the former to separate and pass off in the form of gas ; but chemical affinity coming into play causes them to unite, and form new compounds, partly with each other, partly together or separately, with carbon. Among the combinations that are possible, those, of course, will take place in which the elements have the strongest attraction for each other under the circumstances and existing temperature, and, according to Berthelot, they will be those which evolve most heat by their combination. Hydrogen and oxygen combine in the simplest and most stable manner to form water ; the excess of hydrogen which is common to all fuel of the coal class, takes up as much carbon as the temperature admits of, forming marsh gas and olefiant gas, while at the same time the united action of the two other elements on the carbon gives rise to a series of ternary compounds. The simultaneous production of all these energetic compounds at a high temperature induces fresh activity, and products of a subsequent action are the final result. In short, the nature of the process admits of the production of an almost innumerable series of compounds. Many of these products are formed in every case of destructive distillation, and some of them require more particular notice. In addition to the gases (carbonic acid, carbonic oxide, hydrogen, marsh gas, and olefines), a liquid is obtained, the upper stratum of which is an aqueous solution of various substances, amongst -which' acetic acid and ammoniacal salts are the most prominent; whilst the lower stratum, is a mixture of compounds analogous to the resins and ethereal oils, very rich in hydrogen, and is technically called tair. Pyroxylic spirit or wood sjnrit, a kind of alcoholic compound, is obtained when wood is the substance charred. When any of the varieties of coal are submitted to dry distillation, the products vary; we then obtain from the tar, in addition to the substances discovered by Reichenbach (paraffin, picamar, creasote, kapnovior, pittacal, and naphthalene), pyrogenous resin, numerous oils, and coal-tar-naphtha, a liquid containing various neutral, basic, and acid compounds. The less oxygen there is in the fuel, and the more the hydrogen preponderates, as is the case in coal, the more numerous are the products of decomposition which the latter element forms with the carbon. However much the formation of highly cai'bonaceous products may be facilitated by a suitable temperature, in no case are we able with wood, and still less with turf, or with brown or common coal, to compel the two other elements to combine with and eliminate the whole of the carbon ; a certain portion of fixed, carbon is always left, its quantity depending on the degree and rate of heating. The original form and structure of wood, brown coal, and turf are retained by ihe charcoal left by each, so that year-rings and cells may be distinguished in wood-charcoal, which indicate the kind of wood from which it was produced. Coal is aifected differently, having a different 88 , WOOD CHARCOAL. elementary composition. Some kinds pass during the process of decomposi- tion into a soft state, or kind of fusion, so that the gaseous products of decomposition are evolved in bubbles, as it were, from a paste ; this is the characteristic feature of coking coals properly so called, although all coals may leave on treatment a certain amount of fixed carbon. The carbon left by common coal is called oohe ; it is filled with cavities, is more or less dense, and has in general no resemblance whatever to the form of the original coal. The natural moisture, as well as the oxygen present in the fuel which during combustion produces water with the hydrogen, sometimes prevent the attainment of a very high temperature, and therefore it has been the practice, from a very early period, to make use of dry distillation as a means of removing those constituents of the fuel which absorb heat, or as a means of concentrating the heating power, and confining it to a smaller space, besides imparting to the fuel greater strength to resist crushing where confined with a large burden, as in a blast furnace. This is the object of charring wood, or of converting it into charcoal ; and this series of opera- tions has since been applied to peat, brown coal, and particularly to coal itself, the process in the latter case being called coking. From the series of natural, a series of artificial fuels is thus obtained, the production of which we proceed to describe. The manufacture of charcoal and coke is in itself a distinct operation, not directly connected with those to be described in another division of the work, in which the dry distillation of certain kinds of fuel is practised for obtaining tar and the gases simultaneeusly evolved. "WOOD CHABCOAL. Manufacture of Charcoal — On examining minutely the process of combustion, when, for instance, the lower end of a chip of wood is ignited, two well-defined periods will be observed. At first, there is a bright flame caused by the ignition of the volatile products of decomposition, which grows less intense by degrees, and is at last extinguished when the gases cease to be evolved, and the process closes with the faint glimmering of the remaining charcoal. If the chip- is gradually inserted into a narrow closed glass tube as the flame goes out, the charcoal cools without glimmering, from want of air. It is even possible completely to char the chip, in the manner mentioned above, when access of air is prevented from the beginning by heating the wood in a close vessel. The original mode of preparing charcoal on a large scale was conducted on the former principle, without entirely excluding the latter ; but in the more recent methods large close vessels have been resorted to. "Whatever plan is adopted, the amount of charcoal is always found to be greatest when time is allowed for the oxygen to combine with the hydrogen of the wood and form water. Experience has, in fact, proved that the slow process of charring is decidedly preferable ; this may be seen from Karsten's experiments, by the side of which we place those of Stolze and Winkler. Winkler enclosed his specimens in crucibles surrounded with saw-dust, and heated them quickly to redness. As a general result, the woods gave nearly a like amount of charcoal ; and when the process was too rapid, only half the quantity. The following are the quantities obtained from loo parts of air-dried woo 1 : — WOOD CHARCOAL. «9 Charcoal.* Species of Wood employed. Hva Quicli Process of By a SloB ProceBS of Charring. Karsren.t Stolze.t Wintlev t Yoimg Oak . Old „ . 16.54 15.91 25.60 25-71 26.1 22.8 Young Eed Beech Old „ „ 14.87 14.15 25.87 26.15 1 24.6 17.8 Young White Beech 13.12 25.22 1 23. 8 Old 13-65 26.45 Young Alder 14-45 25-65 Old 15-30 25-65 Young Birch 13-05 25-05 244 17.6 Poplar . — 23.8 17.7 Old Birch . 12.20 24.70 24-4 17.6 lOO years old Birch, well preserved 12.15 25.10 Young Deal {Firms picea, D.) Old „ ... 14.25 14.05 25-25 25.CO I 23-4 20 6 Young Fir {Hnus ahies, D.) . Old „ ... 16.22 15-35 2772 24-75 )...5 20.1 Young Pine (IHmis syhestris) 1552 26.07 J. 3. 1 Old „ ... 13-75 25-95 Lime . ... 13-30 24.60 22.8 16.2 Ash — 22.1 19.4 Willow .... — — 22.2 '5-0 Rye straw .... . 13.40 24.60 Fern straw .... . ! 17.00 27.95 Cane stems . ..... 14.65 26.45 The cause of this remarkable difference in the relative quantities of charcoal obtained is explained by the greater portion of the volatile products of decomposition being ' evolved at a temperature of 225° C. (437° F.), leaving a substance resembling charcoal, which is not altered at that temperature, but which contains a considerable quantity of oxygen and h3'-drogen. Eumford obtained the following quantities of residue at iSo"" C. {302° F.) from 100 parts of the different woods : — Oak Elm Maple Pine Lime Poplar 43.00 per cent. 43-27 42.23 44.18 43-59 43-57 When this substance, which very much resembles the red charcoal or "charbdn roux," is heated to a temperature above 225° C. (437° F.), it con- tinues to evolve carbonaceous products of decomposition until the tempera- ture attains a red heat. The greater part of the charring process can therefore be effected at a temperature probably not very greatly beyond 225° C.,but requires a red heat to complete it. As much less carbon is contained in the products which escape below 225° C.,the obvious advantage of a slow process is due to that fact. The modes of charring wood may be classified into such as require accesi of air, and those in which air is excluded. To the former belong the meiler and kiln processes, distinguished by the movable or fixed character of the coverings. * Marc. Bull obtained the same results with air-dried American woods, namely, from 21 to 25 per cent., by igniting angular pieces in crucibles, surrounded with charcoal powder. t The wood used by Karsten was dried in the air, ihat by Stolze at 100° 0. (212° F.), and that by Winkler in a dry room. 90 CHAECOAL BURNING IN MOUNDS. Preparation of Charcoal under a Movable Covering, or Charcoal Burning in Meiler, or Mounds. — The meiler consists of a uniformly arranged stack of wood, partly protected from direct contact with the atmospheric air by a movable covering, composed of turf sods, earth, sand, or charcoal powder, which from its nature enables the burner to regulate the admission of air in any manner that may be required. The woods that are usually selected for charring are pine, fir, larch, oak, red beech, white beech, ash, elm, alder, and birch; the wood from trees of middle age is preferred, both old and young wood affording a charcoal less dense and hard. The proper age of the different woods will depend on the rapidity of their growth and general longevity, modified, however, by climate and soil. The following data may be taken as a guide : — Age of perfect growlh. Age at which it may be felled for charring. Scotch Fir 140 years 80—100 yearn Spruce „ . . . ISO „ 70- 8q „ Silver „ 80 — 100 ,, 60 „ Larch 80— 90 ,, SO „ Oak 200 — 250 , , 50— 60 ,. Bed Beech White „ / • ■ • 120 — 140 ,, 120 „ Elm 80 „ 20— 30 „ Alder .... 18 — 20 „ Birch 7o „ 20 „ The most appropriate season for felling is the winter, when there is least sap, and when the w:ood is consequently more quickly dried, and less liable to suffer from dry rot. Wood, half air-dried, is found to jdeld the densest charcoal ; if the wood is too damp, the heap is kindled with difficulty ; if too dry, a waste of charcoal results from its greater combustibility ; if the wood has suffered from rot, it affords a less dense charcoal. Wood felled in winter, and properly stacked in an airy situation, will be fit for charcoal burning by the end of the ensuing summer. Logs more than 6 inches in diameter must be cleft, and the usual length of the logs is from 3 to 7 feet. A dry spot is cleared at the proper season of the year, which is during the summer months, sheltered from the wind (by a declivity or a wood) ; it should be at no great distance from the place where the wood is felled, that the expense of carriage may not be great. The ground must not be damp, or too dry and porous, as in the former case aqueous vapour would rise, and be converted by contact with the red-hot charcoal into carbonic acid and hydrogen ; in the latter, currents of air would obtain access to the meiler through the porous soil, and consume a portion of the charcoal. If there is cause to distrust the drjmess of the locality, it is well to cover the ground itself, or, after having first made a litter of shingles, planks, or billets, with a layer of charcoal powder several inches in thickness. The construction of the meiler commences at the centre by erecting the stake or quandel as an axis, from which the meiler is afterwards set on fire. This is either a strong post. Fig. 17 (p. 9 1 ), around which the logs are arranged concentrically, taking the precaution to leave a free channel at the bottom from the stake to the periphery, that burning coals" may be introduced, or three perpendicular logs are connected together with cross-pieces, Fig. 1 8, so as to leave a kind of open chimney. Whichever plan is adopted, the ignition always begins from the foot of the stake. Easily combustible pieces, such as partially charred wood from a former process, are placed about the stake, and round these the logs, which must be CHAECOAL BURNING IN MOUNDS. 9 1 as nearly as possible of the same length, and so arranged one above the other in the form of a ring as to leave as small a space between them as possible. The hewn logs are arranged with their sharp edges towards the stake, the bark side being outermost, and all spaces occasioned by crooked blocks must be carefully filled up with small wood, Fio. 32. It is evident, from this table, that the amount of combustible matter in equal volumes of charred wood, does not increase after exposure to heat for five hours, whilst a continuance of the heat beyond that time occasions an absolute loss; it is advantageous, therefore, to stop the process before the formation of black meiler-charcoal is effected, a prac- tice which is already becoming general. Wood imperfectly charred, so as to leave in the product the maximum quantity of CHAEBON KOUX. I I I combustible matter per volume, is called red charcoal (charhon ronx). Jn France and Belgium, where this kind of charcoal is in use, it is prepared by a kind of meiler carbonization. The meiler is more in the shape of a pile, lengthened out, and erected over a channel a formed in the ground. Figs. 32 and 33. The heated gases of a fire, situated at one end at P, Fig. 33, are forced, by the motion of a fan v, to pass along the channel r into a, whence they permeate the whole mass of the wood, which thus becomes heated, and under- goes dry distillation. On the outside, the heap is covered with a layer of earth, through which the gases are allowed to escape at those parts to wliicl' Sia. 33. it is desirable to direct the heat. The operation is, therefore, regulated in the same manner as in the meiler with movable covering. The results obtained by Sauvage in this way have not been satisfactory, the wood being either insufficiently charred — in fact, not more than kiln-dried ; or if more heat was applied the wood was ignited. The waste gases from smelting or blast furnaces have also been employed in the manufacture of red charcoal, but with no better success. Experience and practice may possibly enable the fur- nace charring of Schwartz (p. 103) to be so modified as to afford red charcoal of uniform quality, but it appears difficult to adapt Schwartz's principle to meiler carbonization. The introduction of charhon rcmx into a country is of importance, as it effects a great saving in the consumption of wood, the scarcity of which is always on the increase. The great difficulty appears to be in produxjing red charcoal of uniform quality in large quantities at once. Heated steam has been employed by Thomas and Laurent, and, according to Heyss, de la Croix employed a patent process, both in Belgium and Austria, for charring wood, turf, and coal by means of heated steam. Violette appears to have prepared excellent red charcoal for gunpowder manufacture by this means. Whether, however, the expense of transporting all the wood to a stationary boiler in the neighbourhood of the consun\ption will not be too great when the charcoal is to be used as fuel appears ques- tionable. Violette's process will be described under Gunfowdee. The produce of red charcoal depends entirely on the degree of heat employed in the carbonization. The red charcoal prepared by heated steam for gunpowder-making at a temperature of 300° C. (572° F.) was found to vary from 42 to 36 per cent, of the air-dried wood, according as it was exposed from one to three hours to the heat in the cylinders. Much of the hydrogen and oxygen of the wood are retained by the red charcoal, and, assuming kiln-dried wood as composed of 50 per cent, of carbon and 50 per cent, of water, red charcoal will probably contain about 75 per cent, of carbon and 25 per cent, of oxygen and hydrogen, although these latter are no longer in the relative proportions in which they unite to form water. The amount of ash is less in red than in black charcoal^ a larger quantity of charcoal being obtained from the same weight of wood. The mean quantity is estimated at 1.5 pei- cent. Red charcoal, being less porous does not absoi-b water from the atmosphere with the same avidity as black. 112 MOULDED CHAECOAL. and no experiments have been recorded as to the actual quantity con- tained in it. Freshly prepared red charcoal ignites much more readily than black, owing to the volatile combustible matters it contains ; it produces a long, powerful, and luminous flams, ^'"- 34- but not equal to that of kiln-dried wood. From the very variable nature of red charcoal, it is diflS.cult to arrive at any accurate knowledge of the composition of different qualities; but the following may be assumed as the average composition : — Fresh. Old. Carbon 74.0 66.5 Oxygen & Hydrogen 24-5 ■■ 22.0 Ash . i.S '•5 Hygroscopic Water 0.0 10.0 Moulded Vegetable Char- coal. — The manufacture of vege- table charcoal in moulds is a branch of industry which attracted some attention in France, one manu- factory producing upwards of 2000 tons per annum in Paris in the year 1859 or i860. Mixtures of it with animal charcoal and a starchy or sac- charine binder are also burned for filter-making. The raw materials, so to speak, consist of the waste powder from wood charcoal, peat charcoal, twigs, brushwood, charred tan, &c., and tar or liquid pitch. Fig. 35. The whole is reduced to a coarse powder between fluted iron rollers, and then thrown on the bed-plate {HH, Fig. 34) of a mill, working with a pair of conical fluted stones A A, made of cast-iron. The upright shaft JB is driven by the pinion D working into the mitre-wheel C. A scraper follows the stones in the usual manner ; 7 to 9 gallons of tar are added MOULDED CHARCOAL. 113 to about 2 cwts. of charcoal-powder, which are intimately mixed by the stones, and become a thick, homogeneous paste, which is discharged at the slide F by the scraper M into a box at E. This mill requires one-horse power, and prepares from 6000 to 7000 gallons per twenty-four hours. The paste is moulded by the machine shown in Fig. 35. A strong wooden beam is raised and lowered alternately by an eccentric motion 'Fiu. 36. communicated to the rods /./, I' J'. Two collars which slide upon two iron uprights H G, and //' G', guide the beam A B. The iron pistons ahcde oi unequal length are firmly attached to the beam AB. Two women are constantly employed filling the funnels fff with the paste, which is pressed into the moulds by the pistons h d, while the horizontal movement communicated to the metal casting E E as shown Tia. 37. At LK immediately carries the full cylinders under the pistons ace, which expel the moulded paste, and thus the operation proceeds continuously. The power required to work this machine is equivalent to that of six 114 MOULDED CHAECOAL. Fig. 38. Fio. 39. horses, and it employs one man and four women, who make about 450 bushels of these cylinders per day. The cylinders are air-dried for thirty-six to forty-eight hours before being exposed to carbonizaticm, which is conducted in a muffle furnace as shown in Figs. 36, 37, and 38. The muffles A A, about 4^ inches thick, must be strongly built, and are heated by a fire at £. The flame heats the muffles all round, passes behind them through flues C D, returns in front by E, and finally passes off by the open- ings // through the under- ground flues g g g to a high chimney at the back. The dry-moulded cylinders, 4^ inches long by i^ inch diameter, are ranged in two layers in sheet-iron boxes H H, or cast-iron cylinders / /, and the whole placed on trucks jj, Fig. 39, which are then run into the muffles. A metal door K (Fig. 37), lined with brick and luted with clay, encloses the whole until the carbonization is com- plete. The moisture remaining in the moulds, and the carburetted hydrogen, produced by the increasing heat, make their escape through the small flues h h, and after the lapse of a certain time, when the cylinders have become red hot, a small current of air cau- tiously admitted at m m ignites these gases. The heat thus produced is .suffi- cient to finish the operation. Two muffles are charged every six hours, and each muffle is filled twice in the twenty-four hours. The cylinders are withdrawn as soon as the flame ceases to appear, which the work- man ascertains by opening the air- flue m. The waste cut- tings and brush- wood which are not adapted for the plan described above, are con- verted into com- mon charcoal in furnaces shown in Fig. 40, con- structed, like coke ovens, of a strong outer wall E with an opening C at the Fig. 40. PEAT CHARCOAL. II5 top, and another at A at the level of the floor. The cnarcoal is drawn into a pity filled with water. The wood is thrown in by degrees, and drawn every seven hours, or as soon as a flame appears at C, which is then immediately made tight by an iron-plate B. Each furnace produces about 8 cwts. of charcoal per twenty-four hours, from about 26 cwts. of wood. The moulded charcoal, being more dense than that made by the old plan, is useful for domestic purposes — it burns longer, and does not lose so much heat by radiation PEAT CHAECOAL. Preparation of Peat Charcoal. — Two circumstances are very favour- able to the charring of peat in the meiler ; first, the rectangular form of the peat bricks, which admits of their being piled up together without leaving those interstices so prejudicial in the wood meiler ; and second, as peat charcoal is less combustible, such care and minute attention to the process are not necessary ; moreover, the meiler may be constructed of much less circumference, with advantage. The peat bricks for charring are often cut somewhat larger than those used commonly as fuel, and of these from 5000 to 6000 constitute a meiler, the dimensions of which seldom exceed 10 feet in circumference, containing altogether about 1500 cubic feet. The stake or quandel is erected on a dry spot, and round it the turf -bricks are ranged endwise in concentric circles, diminishing in number as the height increases, so as to give a hemispherical form to the meiler ; air-channels, radiating from the centre, of the width of a single brick, being left in all directions to admit air to the interior, which, from the close manner in which the turf packs, would not otherwise be acces- sible. At the foot of the stake, some dry wood is placed for ignition ; the meiler is covered with an inner coating of moss and leaves, and with an outer one of earth or charcoal dust, leaving only the middle part of the hood round the stake uncovered, for the passage of the gases after the meiler is ignited by one of the open channels. By opening and closing these channels, the combustion proceeds in all directions until flame appears at the aperture in the hood, which is then closed, while holes are pierced all round the covering, consecutively from the top to the bottom, at distances of a foot apart, until the charring is completed. The appearance of the smoke issuing from these apertures indicates the stage and state of the operation, which must vary in its management with the age, density, and other physical properties of the peat. The produce from the mounds has heen found to be as follows :— from not quite air-dried peat, 24 per cent, of the weight and 27 of the bulk have been obtained; from air-dried, 27 per cent, in weight and 32 J in volume; from freshly dug Pfungstadt peat, 30 per cent, in weight and 29 in bulk; from excellent peat, quite dry, 35^ of the weight and 49 per cent, of the bulk. In the district of Siegen, very good peat produced 23 per cent, of the weight and 40 per cent, of the bulk. Experiments on a small scale generally afibrd a still larger produce, sometimes as much as 40 per cent, of the weight. Some difficulty is found in extinguishing the peat meiler ; a thin paste of clay and water is found serviceable in accelerating the operation. The peat charcoal is very apt to fall to powder, in which state it is useless as fuel. Peat Charcoal ' Kilns. — The use of kilns aflbrds no increase of produce, but a safer regulation of the heat, and is better adapted to peat than to wood, as the former is always obtained on the same rpot, and it is not necessary, as in the forest, to follow the clearing or to transport the material. In the manufactory of arms at Oberndorf in WUrtemberg, kilns are employed which have stood the test of five years' experience, and have I 2 ii6 PEAT CHARCOAL KILNS. Fio. been approved; one of these is represented in Fig. 41. It is in the form of an upright cylinder, 9 feet in height, and 5I feet in diameter, closed at the top by a circular arch, and with a capacity of about 200 cubic feet. The kiln itself, b, is surrounded by a second wall a a, in such a manner a.s to leave a space c c, which is filled with sand, to prevent loss of heat by conduction. Both walls are of brick, each 1 5 inches thick, the space c c being of the same dimensions, so that the entire thickness of the walls is 45 inches, d d are stones, placed longitudinally and perpendicularly, to give greater solidity to the walls. Above the sole of the furnace are three rows of draught- holes, formed of pieces of old gun-barrels walled in, which can be readily closed. The door for withdraw- ing the charcoal is closed by the cast-iron slab f ; the iron sup- port of the door projects slightly forwards, and in front of it is a deal board e, the space m being filled with sand from g. A space is left in the centre of the kiln for igniting the contents. In the beginning, both the aper- ture i, through which the charge of peat is introduced, and also the lower draught-holes are left open, but as soon as the peat, when viewed through these, ap- pears white hot they are closed, and the upper ones opened. When no more smoke is visible, the apertures are all stopped, or filled with sand, and a layer of sand about i foot thick is covered over the aperture i ; this takes place after about forty to forty-eight hours, when the kiln is left to cool during six or seven days. In order to save time, water is sometimes poured on to the charcoal from the aperture i. Ten of these furnaces are worked at the same time, in order to afford a constant supply of charcoal. Peat charcoal, as far as heating power is concerned, ranks among the best kinds of fuel ; it possesses, however, at the same time, quahties which render it unfit for many purposes. If 100 lbs. of dry peat leave 21 lbs. of ash, and produce 47 lbs. of charcoal, these 47 lbs. of peat charcoal will contain 21 lbs. of ash, or 45 per cent., which large amount must interfere in many of its applications from its mere bulk, and in others from the tendency it has to fuse and combine chemically with the substances heated in contact with it ; while the phosphates and sulphates it contains are objectionable in many metallurgical processes. Those varieties of peat which contain a large amount of ash are, consequently, quite unsuited to the manufacture of charcoal. Another great objection to peat charcoal, is its loose brittle character, whi-.:h soon causes it to fall to pieces, and become useless; in smelting furnaces, the pressure of the layers of ore suffices to crush it to powder, in which state it so materially obstructs the blast as to derange the entire process ; its application is, therefore, confined to boilers, evaporating pans, forge fires, and domestic purposes, whilst even for such it is inferior to kiln-dried peat. This want of firmness has been found to render the charcoal quite incapable of bearing carriage, unless admixed and moulded, and the carbonization must, therefore, be effected on the spot where the charcoal is to be used. Stones patented a process for compressing peat in boxes, between rollers PEAT CHARCOAL KILNS. "7 in such a manner as to afford hard, square bricks, which are afterwards heated in retorts of wrought-iron, similar, in size and shape, to those used in the manufacture of illuminating gas, with an apparatus for condensing the products of the distillation in a series of receivers so as to separate them to a certain extent without a second distillation ; the combustible gases being employed as fuel for heating the retorts.* Vignoles employed steam, heated to 450° or 460° F. (230° to 236° C), which is between the melting-points of tin and lead, for charring peat in upright cylinders ; the peat having been previously dried, either by a. current of hot air produced by a fan driven by the waste steam from the apparatus, or by a hydro-extractor in which centrifugal force is employed to expel the moisture. Fig. 42 represents a veiHiical section and partial elevation of the apparatus. a represents a section of the large cylindrical steam boiler set over a furnace, the flues from which pass round the cylindrical carbonizing vessels, two of which are shown in the drawing to the left of -the boiler and of which there are six on each side, arranged round a central coil of pipes H, in which the steam from the boiler a can be heated to the required temperature before Fig. 42. its admission to the carbonizing vessels. The steam, having passed from the boiler through one department of the red-hot coU, is conveyed into one of the carbonizing vessels ; whence, having sufficiently charred the peat, it passes through another part of the coU into the next, and so on, until having passed through all six it is employed to work a low-pressure engine, which drives a fan, the current of air from which is heated, by passing through pipes, to 250° F. (121° C), before it is admitted into chambers where the moist peat is exposed to dry. The cylindrical carbonizing vessels are composed of boiler-plate, conical at the bottom, where they are furnished with a steam-tight man-lid or door for removing the charred peat, a similar door being fixed in the dome-shaped upper part for its introduction. The charred peat, if exposed to the air, would be liable to spontaneous combustion ; it is discharged, therefore, into iron cooling-boxes p placed below the carbonizing cylinders, and low-pressure steam is blown once or twice through it. Eogers carried out a system of drying and charring peat in Ireland, the principle of which will be seen by reference to Figs. 43 and 44. A long shed, shown in longitudinal section E E, Fig. 43, is constructed over a feunk channel or ash-pit, traversing its entire length and built with bricks, on the margin of which a railway is laid down to enable small travelling chambers or kilns A to travel easily through the shed and over the ash-pit. The kilns A are made of sheet-iron on a framework of iron with wheels, the bottoms being constructed of bars which serve as a grate. They are filled with the peat to be charred by inverting them, ^nd then inserting the grate. The interior part of the shed, through which these travelling ovens * "Eep. Pat. Invention," 17, 16 ; 19, 220. ii8 PEAT CHARCOAL KILNS. , is formed into a kind of chamber by sheet-iron plates B B, through which, at regular intervals, are pipes D D leading to the top of the shed. Within these vertical pipes are placed other movable pipes which fit on to the tops of the kilns and perform the part of chimneys ; they can be moved S'lo. 43- Fia. 44. up and down sufficiently to admit the upper part of the kilns to pass below them. The sides of the shed are filled up with lattice-work shelves for the reception of the air-dried turf-bricks, and the slanting sides are protected from the rain by movable louvres H H, Fig. 44, which can be opened or closed at pleasure, and when supported by a few sods of turf below, serve as stepping-places for the workmen when employed in filling or emptying the shed. When the shed is packed, and the kilns are filled with turf and arranged under their respective chimneys, these latter are opened at d by the rod e, and the turf is ignited from below by the ash-pit. The charring is then carried on as in other furnaces of similar construction, a portion of the turf being consumed in charring the remainder, and the draught is regulated by the flue- door at d .and the ash-pit door below. The heat from the kilns is thus made to dry the turf in the shed, and its action is sometimes augmented by a current of air forced through the house by a fan. Green produces a hot draught of air through a drying-house by means of chim- neys and fires, and then distils the dried peat in wrought-iron cylinders placed in pairs over a furnace, and similar to those employed in making illuminating gas, the the turf being consumed as part of the fuel below the gases from retorts. LIGNITE CHARCOAL. Of all kinds of fuel, brown coal or lignite is least adapted for carboniza- tion, although it is decomposed with as much ease as wood, and the charcoal which it produces is not so easily inflammable. The previous remarks on the ash of peat apply with equal force to brown coal, but even the best LIGNITE CHARCOAL. 119 kinds of brown coal are not easily charred, as, during the action of the heat, the single loyjrs, concentric rings, &c., which are scarcely perceptible in the fresh specimens, spUt off, and a compact piece of brown coal becomes thus completely broken up into small fragments, or so fissured as not to bear carriage. Eoschers states that lignite, if thoroughly air-dried when fresh from the pit and very slowly charred, is not subject to this disintegration ; and, according to Mayer, very firm charcoal is obtained by charring the freshly dug lignite without previously exposing it to the air. In experi- ments with lignite from the Hessenbriicker Hammer (in the Wetterau), 15J per cent, by weight and 32 per cent, by volume were obtained by meiler carbonization. This quantity is too small to pay for the cost of manufac- ture.* In the neighbourhood of Cassel, where circumstances are more favourable, the carbonization in mounds has been actually carried out, but only upon a small scale. Good charcoal is rarely obtained from brown coal ; as a rule, it is friable and pulverulent, and difficult to quench when just carbonized. Experiments made with brown coal on a small scale, in which the coal was heated in close crucibles, until all vapours ceased to be evolved, gave the results shown in the following table : — Char- Char- « 100 parts. coal. Per 100 parts. coal. Per cent. cent. Earthy coal from Dax 49.1 /Lignite from Neundorf 38.4 „ Bouch. d. R. 41. 1 , Coulang 38.1 „ ,, Bassee-AlpeB 48. 5 Jahnsdorf 32.8 Lignite from Greece 38-9 , Paredel 1 39-6 ,, Cologne 36.1 „ 2 . 40.7 ,. Iceland 57-5 ., 3 42.0 _ / ,, Raddergriibe 41.6 , Antoni-Zeche 40.0 )7 »* 49-7 , Wellouitzer Br. 35-9 3 Gr. Urwelt 44-3 , Nemtschauer Br. . 34-7 0^ = H JJ 43-9 , Hartenberg I 37-2 11 )) >) 51-3 13 , „ 2 . 34-6 ?« ,, Friesdorf 28.2 1 , Kanden 37-5 «s > ' »> 48.2 1 Pitch ' coal from Grunlat 37-2 «T3 (B '3 Q }j >» * 46.8 m Earthy , Hartenberg i 42.1 ^ Earthy coal from Uttweiler . 68.2 „ „ „ 2 48.4 03 ,, ,, Kaddergrube 48.3 3 36.8 I ^ )» •• j» 46.4 11 " 11 4 39-0 c8 Lignite from Putzchen 46.4 Pitch , „ I 43-9 4> it 44-7 2 40-3 40.6 )) ' n ■ 29-3 •a „ Orsberg . 62.8 Altsuttel 40.3 X ., 68.4 V „ 35-0 Aussig 40.1 Bavarian f Earthy coal from Verau . Oberpfalz | Lignite „ 3S.6 >t yt 40.0 46.0 , , Heirendorf 41.2 CARBONIZATION OP PIT COAL. In some Scottish localities, in the neighbourhood of trap dykes, coal is found to have been changed to coke (" carbonite "). Similar effects have been noticed (1882) in Midlothian, Chesterfield Co., Va., where the car- bonite seam is 15 feet thick. The American mineral is reported to contain about 80 per cent, fixed carbon, 3.2 to 6.7 per cent, of ash, and 1.6 to 4.1 of sulphur ; it much resembles anthracite. * One cwt. of coal costs 5|ri, one cwt. of charred coal about 3s. iitl I20 DESTRUCTIVE DISTILLATION OF COAL. General Principles. — The products formed during the charring of coal, although similar in kind, differ considerably from those obtained under the same circumstances from wood. This might reasonably be anticipated, from the different elementary composition of the two substances, the dissimilar arrangement of their elements, With the addition of nitrogen and sulphur (partly organic, and partly as pyrites), and the higher temperature required to complete the carbonization ; the nature of the products very much depends on the temperature employed. In addition to the solid coke as residue, both ' liquid and gaseous compounds are produced ; the former being differentiated into an aqueous and oily portion, the latter containing many of the com- pounds found in wood-tar, but also numerous other substances, which will be described in another place. As a general example of the products obtained in the dry distillation of coal, and their relative quantities, the following analysis, in the course of which coal was submitted to a slow distillation in a close vessel, may be adduced : — Coke . . 68.925 Liquid (Tar 1 2. 230] products (Water . . 7-S69j /Marsh Gas (OH J . . 7.021, Garbonio Oxide i. 13S Carbonic Acid . . . . I-07.3 Olefiant Gas (Cjfl,) . . 0.7S3 Sulphuretted Hydrogen . . o. 549 / Hydrogen . . 0.499 Ammonia 0.21 1 'Nitrogen . . . 0.035 products = 19-799 = 11.276 The relative quantities of these products, as well as the nature of the tar and water, vary with the temperature employed. When the charring goes on with access of air, a portion of the coke as well as of the gaseous products of distillation is consumed in carbonizing the remainder. The following table of the products of the destructive distillation of coal is taken, with the author's sanction, from the recent third edition of Pro- fessor Mills's "Destructive Distillation." Boiling-points and melting-points are given, so far as known. PRODUCTS OF THE DESTEUCTIVE DISTILLATION OF COAL. Name. Formula. B.P. M.P. Deg. C. Dcg. C. Hydrogen H, -2IS • Methylic Hydride (Marsh Gas) CH, - 144 ? Hexylio „ CeH,, + 68 Ootylic „ ... CioHm 119 Deoylie „ 171 Paraffins . . CnHm + 2 ns (fl-nii), cakini; coal . . , -^ 80C + 240H + 5O . 48 Coal from Grand Croix (marechal), highly caking = 80C + 112H + 3O . 37 It will be seen that the property of caking generally increases with the quantity pf hydrogen and oxygen, particularly with that of the hydrogen. Anthracite, consisting almost entirely of carbon, may be viewed as a kind of natural coke ; the quantity of hydrogen rises in the others in proportion as they soften in the fire, with the exception of the last, which possesses this quality in the highest degree, although its hydrogen amounts to only half the quantity contained in the caking coal from Mons. The same fact has been remarked with the younger coal of Obernkirchen, which is also of a highly caking character. It also produces a porous, friable coke, and has the composition 80C + 104H + 3O or O : H = i : 35. Dr. Percy has shown that the amount of " disposable hydrogen " may DESULPHUEIZATION OF COKE. 123 be the same both in caking and non-caking coal. It may, however, be observed that, in the case of curly cannel from Leeswood Green Colliery, Flintshire, when the disposable hydrogen much exceeds about 4^ per cent., the caking property disappears. Finally, Stein of Dresden has shown that caking coal and non-caking coal may both have the same ultimate com- position. On the whole, it appears probable that, whilst "disposable hydrogen " doubtless confers fusibility, the real source of caking lies in a resinoid body or bodies, identical in composition with coal itself. Desulphurization. — The production of coke is undertaken with the same general object in view as the production of wood charcoal ; but it is desirable, for many purposes, to free the coal from sulphur. In this sense, the production of coke may also be called a desulphurization of coal, but it has been also found necessary to attempt the removal of sulphur remaining in the coke. Desiilphurizatioii of Coke. — The subject of the various processes for the desulphurization of coke has been investigated by A. Philippart, a Belgian engineer (i?e«Me Univ. des Mines, &c., i87i,xxviii. 261-318), wiih the result that none of the methods which he examined has succeeded on a practical scale. Indeed, as to most of them, Dr. Percy remarks that the term de- sulphurization is improperly applied, inasmuch as their object is not the elimination of sulphur, but merely its transference from the iron (of pjrrites), in combination with which it usually exists in coke, to some other substance so as to form a combination not injurious in subsequent operations, such as smelting. The various methods proposed for desulphurization during coking are : I. Heating the coke to redness in a current of steam. II. Heating the coke to redness in a current of air under ordinary pressure. III. Heating the coke to a lower temperature than redness in a current of air under increased pressure. IV. Mixing common salt with coal previous to coking, or the use of a solution of chlorides added to the coal during coking. V. Mixing other substances, such as carbonate of soda, lime, carbonate of hme, or oxide of manganese, with the coal previous to coking. VI. Coking with common salt, and subsequently washing the coke. I. The method of applying steam to coke during coking, or before the coke is drawn, was patented by Claridge and Roper in 1858. They proposed to use in the coke oven a false perforated bottom, underneath which, at any time during the process of coking, steam could be admitted and made to ascend through the coke. Scheerer (B. u. H. Zeitung, 1854, xiii. 239) had, however, published in 1854 the results of an experiment in which high- pressure steam was passed into an oven before drawing the coke. The coke thus treated was found to have lost 0.4 per cent of sulphur. Philippart's experiments with this process gave the following results : — state of Combination of Sulphur Percentage of Sulphur Before Desulphurization. After Desulphurization. As Sulphide „ Sulphate ., 0-57S 0.050 0.450 0.040 0.625 0.490 II. This process was experimented on by Philippart, with the result that in one case 10 per cent, of the total sulphur was converted into sulphurous acid, but the loss of carbon by oxidation amounted to 55 per cent. In 124 SULPHUK .IN COAL. another case 30 per cent, of the total sulphur was converted into sulphurous acid, and 18 per cent, of carbon was lost by oxidation. III. In experiments made with air at 2 to 2^ atmospheres (the coke being heated to between 250° 0. and 300° 0.) it was found that only 7 per cent, of the total sulphur was eliminated, but the loss of carbon was not so great as with air at atmospheric pressure. IV. This was the process of the late Prof. Grace Calvert of Man- chester, his object apparently having be6n to form volatile compounds of sulphur and phosphorus with the chlorine of the common salt. Calvert sent to Dr. Percy the results of an experiment in which coke prepared without salt from a North StaflFojrdshire coal contained 2.56 per cent, of sulphur, whilst with salt from the same coal the coke contained only 0.72 per cent. Philippart's experiments with this process gave the following results : — No. of Coal. Percentage of Sulphur In the Coal. In Coke without Salt. In Coke with 10 per cent. Salt. 1. II. III. 0.50 4.25 0.50^ 0-45 2.30 0.46s 0.47s 2.2s 0.67s Y. The use of these other substances has resulted merely in fixing the sulphur and providing an agent to neutralize its bad effects in iron smelting, &c; They have not been employed on the large scale. VI. In order to avoid fixing the sulphur in the coke by forming sulphites and sulphates, T. Rowan patented in 1868 a process of coking coal (or calcining ore) with salt, and subsequently washing the coke (or calcined ore) by immersion in water. This process gave some promising results in experiments both with coal and with ironstone, but it has not been introduced on a large scale. The fact that the bulk of the sulphur found in coal exists in the form of iron pyrites (or " brasses ") which may readily be removed by washing, providing the coal has been sufficiently broken or crushed, has led to the gradual introduction of this method of cleansing the coal — ^the more so, as other impurities, such as shale and slate, are also removed by the same process, and the effect of crushing the coal is to produce a more uniform and dense quality of coke. Sulphur not present as sulphate or as pyrites is termed " organic sul- phur," because it is believed to be in a state of combination with carbon and hydrogen. It is probable that, when adequate heat is applied to coal, the whole of this sulphur distils off, at an early period, in combination with hydrogen. The organic sulphur of coal has been but vei-y little investi- gated. Iron pyrites is one of the most injurious mineral ingredients of coal, as the sulphur in it is far from being completely removed by the operation of coking, whUst the oxide of iron which remains in the coke forms with silica from the ash a slag or scar when the carbon is consumed. This scar, covering the grates of a locomotive furnace, for example, prevents the free access of air, and consequently wastes the fuel, as the latter is to a much greater extent converted into carbonic oxide, instead of being completely oxidized; this diminishes the speed by arresting the rapid production of . steam. It has been found in practice, therefore, that a coke which leaves a white ash, although this may be twice as much as in the case of another yielding oxide of iron, is much superior for locomotive purposes. Fortunately, this con- stituent of certain cokes actually renders them more adapted for smelting COAL WASHING. 125 some lead-ores than the others ; as, for example, on the east coast of Spain, where the oxide of iron acts as a precipitant for the lead in the furnaces. COAL--WASHI]SrG MACHINES. As the presence of sulphur or pyrites is so injurious where coke is employed for locomotives, in re-melting iron for foundry purposes, or in the manufacture of iron in blast furnaces, it is becoming the practice pretty generally to remove pyrites and other impurities from the coal by mechanical means, which are also employed for cleansing dross which is to be used without being made into coke, and small coal which is to be made into bri- quettes or into patent fuel. This is effected by various methods of washing the coal, all of which depend for their action on the difference between the specific gravity of the coal and that of the mineral impurities which it contains. Apart from modifications in structural details, these machines may be divided into two classes — viz., those which operate by agitation of the water produced by the movement of a piston, and those which act on the principle of the sluices used in washing auriferous and other ores. The piston machines have the advantage of economizing the quantity of water used, but only a few of them carry this to the point of using the same water over and over again. Some of the best-known plans are shown in the following illustrations : — Fig. 45. Fig. 46. coal. Figs. 45, 46, 47, 48, shqw designs of a piston cylinder for washing the 126 COAL WASHING MACHINES. A B C D, compartments for the grate. E F, grate on which the coal rests. G H, bars below which the shale accumulates. B K G L, compartments for the piston M N. I''i8. 49. Fig. so. Kgs. 49 and 50, plan and section of the sluicing process employed at Commentry. R S, channel for conveying the water to the washing place. T, channel intended for the washers A B G D and A, B, G, D,. A A, sluices for regulating the admission of the water. BCD B, G, D, three distinct compartments for washing. E F, exit for the water. Fio. SI. COAL WASHING MACHINES. 127 Fi&. 52. Figs. 51 and 52, plan and section of the sluicing washers at Felessin. A B, general canal for conveying the water to the apparatus. C, regulating sluices. G D, canal for admitting the water. E, first compartment, where the stones are deposited. F G H, other compartments. /, the point where the steel division is placed to retain the coal. K, exit for the water. The general results are said to be that three workmen, during the twelve hours, can wash 11 to 15 chaldrons, and the produce is in 100 parts : Washed coals . . . 8q Shale .... 2 Small coal . . . 9 whilst the quantity of ash in the coal has been reduced nearly one-half. The small coal contains 20 to 25 per cent, of ash. The cost may be calcu- lated from the French data, as follows : — d. Labour . 5.1 Other charges 1.2 Loss ... 8.3 14.6 or about \s.2d. per ton of washed coals, which, on a produce of 66 per cent, of coke, would make the cost is. \od. per ton of coke. Meynier's coal-washing machine consists of a force-pump of large diameter, connected with a chamber of wrought iron, into which water is forced and made to ascend through a heading of wood pierced with holes, so as by continued movement the cleaner portions of the coal are made to flow to the upper portion of the wrought-iron chamber, and thence over the lip on to a curved drainer (as shown in plan Fig. 53), from whence they are raked on to a paved platform and filled away. The drainer may be made either of wire gauze or of perforated iron, supported in its place by iron bars, and the water which goes to the channel below it can flow round the pump and be lifted again if necessary. Between the force-pump and machine, there is a slide valve to regulate the flow of the water, and branch pipes are shown in plan and section (Fig. 53) by which the other chambers requisite may be supplied in a range of washing machines. Between each alternate machine is placed a mitre valve to allow the pyrites and dross to descend into the chamber below it, from whence it can be cleaned out as it accumulates. The motive power is not shown, but it may be either steam or water. The cleading ought to be inclined towards the mitre valve, as shown on the plan, so as to facilitate the descent of all substances of superior specific gravity to coal itself to that point. 128 COAL- WASHING MACHINES. About 2 inches from the upper surface of the coal, when the machine is full, iron bars are placed so as to admit of a plank being placed on them, by means of which an operator can reach any part to clean or arrange it during the progress of the work. The flow of water can be further regulated, in the case of the pump being larger than the requirements, or machines in use, by having an escape valve loaded to such a pressure as the work requires. Fig. S3. The spouts for feeding the coal ought to be so placed as to cause the coal to pass regularly over the cleading, and subsequently be submitted to the action of the water. The arrangement as shown is for an ordinary truck, similar to those used in the. Midland Counties traffic ; but this can be modified according to circumstances. B^rard's machine was exhibited in London at the Exhibition of 1851, and also in Paris in 1855, and received awards. It carries out the following operations : — COAL-WASHING MACHINES. 129 1. Sorting the coal by throwing out the larger pieces. 2. Breaking up the pieces which are too large for washing. 3. Continuous purification of the coal. 4. Loading the washed coal into waggons. 5. Loading the refuse (pyrites, schist, or slate) into waggons for removal. A machine to operate on 80 to 100 tons of coal per twelve hours requires from four to five horse-power. Fig. 54 illustrates this machine. Fia. 54. The coal to be washed is run on to the staging A by trucks B, or is raised by elevators and delivered on to the table or movable grating D, which is formed of a series of sloping plates, each plate perforated with holes of a smaller size than the one above it. These gratings are suspended by rods, and have a motion and concussion given to them by cam mechanism, so that the coal is quickly sorted according to its diiferent sizes, which are delivered at difierent levels. The larger pieces, which do not penetrate the perforations in the first plate reach the picking-table E, where stones, fragments of iron, and the like are picked out by hand. Those pieces which have passed through the first plate, and are retained by the next, are delivered to the crushing-rollers F F', while the finer portions, which have passed through the second plate, fall directly by the shoot e into the pit A' , where the coal which is passed through the crushing-rollers also accumulates. It is raised from this point by an endless band with elevators J, and delivered by the shoot / to the perforated table, m' , which is placed above the inclined side of the well L. This side is inclined at an angle of 45°, and on the opposite side is a cylinder 0, in which a piston works. The bottom of this cylinder communicates with the well L, at about half the height of its vertical side, and the down- ward motion of the piston causes the water which fills the well and cylinder to rise through the perforated table m' , in its upward current lifting and floating the particles of coal, while the dirt settles down or is washed off elsewhere. The washed coal is delivered by elevators T to a sorter U, from which it is filled into waggons according to its size. Mackworth's purifier is illustrated in Fig. 55. The water in it is said to have been made to ascend with a speed of I to 2 inches per second, in order that a smaller area of separator could be used than in other machines. 13° COAL-WASHING MACHINES. In working this machine, coal is tipped into the coal-hopper, whence it is conveyed by the elevator in a continuous stream into the revolving hopper of the machine. As the coal is washed, it is raised out of the water by a perforated plate, and delivered by the coal-sweep into a perforated shoot, which conducts it to waggons, allowing the water to drip through the per- forations. The shale and other impurities collect in a shale-box at the bottom of the machine, and are discharged by an elevator or dredger into suitable waggons. The pump or agitator is capable of throwing from 50 to 200 gallons of water per minute, according to the size of the machine. An end- less belt is shown, without buckets, conveying the coal from the hopper into which it is tipped to the machine. By means of the revolving hopper, the coal passes gradually down into the separator, where a current of water is driven upwards through the mass of shale and coal, at a velocity of from 4 to 5 feet per minute, by the agitator or screw. This water passes back again by the finely perforated Fig. SS- plate, and, with the fine silt suspended in it, is again driven upwards by the screw to undergo a repetition of the process. - The gentle agitation produced by this current separates the shale and pyrites from the coal in the sepa- rator ; the impurities descend through the valves and are taken up by the dredger, while the coal is pushed out of the water by the curved arm or sweep ; as soon as the water has drained off, the coal falls on to the shoot, which conducts it to the waggon. A brush following the arm helps to keep open the holes in the perforated plate. The valves remain constantly more or less open according to the indications given by the dredger, and are regulated by the valve lever. The water required to replace what is absorbed by the dry coal and shale enters by the hopper, and flows slightly inwards through the shale valves as the shale is coming out. It IS said that machines were started in Scotland, Cumberland, Derbyshire, Gloucestershire, and Wales, to purify from 20 to 100 tons of coal per day, at a cost not exceeding 3d. per ton, and with a loss not exceeding 2 per cent, of coal. COAL- WASHING MACHINES. 131 Figs. 56, 57, illustrate the machine constructed and introduced by Messrs. Andrew Barclay & Son of Kilmarnock, who have supplied the sketches and the following description : — The coal to be washed is brought in waggons and emptied into a space cut in the ground, from which it is elevated by buckets and guided by shoots to the washing-cisterns. These cisterns are square boxes with a perforated shelf near the centre, on which the coal lies ; I Fio. 56. the washing is accomplished by the water, being kept constantly surging through the perforated plate by the action of a piston in the agitating- cylinders. The washed coal, which is the lighter body^ is floated over the end of the cistern, assisted by a fan-shaped kicker, into the shoot, and runs down to the screen ; the fine coal, passing through the screen, is conducted by a shoot to the waggon placed there to receive it ; and the larger lumps, or nuts, fall out at the end of the screen into a shoot, and thence to the waggon. As the coal is the lighter body and the dirt the heavier body, it follows that the dirt must fall to the bottom of the washing-cistern. To 132 COAL-WASHING MACHINES. Fig. 57. allow this dirt to be separated from the coal, there is a valve in the per- forated plate opening downwards. When this valve is opened, the dirt Fia. 58. Fio. 59. COAL-WASHING MACHINES. 133 lying on the perforated plate is allowed to drop into the chamber below the perforated shelf ; from thence it runs down a pipe to the dirt cistern. From this cistern it is elevated and emptied into a shoot, which conveys it to the waggons placed to receive it. Each cistern in the machine shown is capable of washing about 60 tons of dross per day of ten hours. The BocHUM Mining and Smelting Company in "Westphalia, in order to obtain a pure coke for their blast furnaces, established in 1878 at one of their collieries a complete set of apparatus for washing the coal on the LtJHRiCH system. Figs. 58, 59, and 60 partly illustrate the plant employed on this system, Fig. 58 being a sectional elevation showing the general arrangement of screens, hoppers, elevators, and washers ; Fig. 59 a section of the large coal washer ; and Fig. 60 a section of the washer used for small coal. Fio. 60. The following description of this plant wsis given by Mr. F. Baare of Boohum before the Iron and Steel Institute in 1883 : — " The washing plant consists of the following parts : — " I. The Briart patent screens, by means of which the large coal is separated from the small, the latter only being treated in the washers. "2. The separating-drum, which divides the coal to be washed into different sizes. "3. The washers for the coarse or nut coal. " 4. The washers for the fine coal. " 5. The disintegrator for washed nuts. " 6. The arrangements for transporting the W&shed coal to the store- bunker. "7. The settling- ponds. " 8. A centrifugal pump for effecting the circulation of the necessary water for the washing process. " The whole of the machinery is set in motion by a steam-engine of about 140 horse-power. The water u.sed for washing is taken from the pit, and is ■conducted through a pipe to the centrifugal pump, by which it is raised into an elevated reservoir, together with the returns from the settling- ponds ; from the latter, the washers are supplied with the necessary water by means of a system of pipes. The quantity of water supplied through the 134 COAL-WASHING MACHINES. centrifugal pump amounts to about 8 cubic metres per minute, of ■which about a tenth part is fresh pit-water. " The operation of washing the coal is conducted in the following manner : — The coal, on being raised from the pit, is tipped from the waggons on to two Briart screens, whence all coal of over 69 mm. is passed on to another screen of great length ; here it is cleaned by hand-picking, and then conveyed to the railway trucks. All the coal that passes through this screen up to 96 mm. is taken to a separating-drum situated in the upper storey of the building. This divides it into the following five sizes : Size — No. I, nut coal, from 96 to 45 mm. ; No. 2, nut coal, from 45 to 24 mm. ; No. 3, nut coal, from 24 to 15 mm.; No. 4, nut coal, from 15 to 10 mm. ; No. 5, small. coal, under 1.0 mm. " To prevent the fine sieves from becoming choked or dirty, an arrange- ment of pipes is provided at the side for keeping them clear by jets of water. " The nut coal falls directly from the separating-drum into the washing apparatus adapted to this size, which stands underneath. The small coal before reaching the washers passes to a system of six grading-boxes, con- structed after the well-known Rittiugec system, where the application of a horizontal stream of water, diminishing in speed towards the last grading- box, sorts the grains of coal according to the time occupied by each in sinking. " In accordance with the number of grades, there are provided four washers for nuts and six for the smaller sizes of the coal. "The most important part in both systems is the bed of stone, laid on a perforated bottoin, which is formed for the nut-coal washers of coarse pieces of slate, and for the smaiU-coal washers of broken crystalline felspar. " The washing process consists in the regular rocking motion imparted by the piston to the water, a stream of which is supplied through an opening situated underneath the piston at the back of the apparatus and regulated by a valve. This peculiar 'lotion of the water favours the separation of the particles of slate from the coal, and at the down-stroke of the piston sufficiently raises and opens the bed of slate or ef felspar to allow the particles of slate to pass through it and through the perforated bottom into the lower part of the trough, whence they are carried away. " The washed product of the nut-coal washers, after passing through a system of draining-sie'res for the purpose of being freed from water, is conveyed to loading-bunkers discharging into railway trucks, whilst the nut coals which are intended for coking have to undergo a second washing on a large fine-coal washer, and are subsequently, by means of a screw, carried on to the- disintegrator. From this, the coal is carried by a bvicket appa- ratus and travelling-belt, and is fed into a larger screw, which conveys the whole of the washed coals that are intended for coking into a store-bunker. " The produce of the fine-coal washers flows into a large receptacle situated at a low level ; from this, by means of a three-bucket apparatus, it is lifted into the large screw mentioned above, the overflow being freed from suspended particles of coal in settling-ponds. " The slate mud discharged by hhe washers is also first conveyed into a box narrowed towards the bottom. The coarser parts are lifted by means of a bvicket apparatus to be carried ofi", whilst the overflow, charged with the finest particles, is passed through two separate settling-ponds. The coarse slates which are separated in the nut-coal washers, and through a side opening drop into troughs, are by means of bucket-wheel 1 lifted from these troughs into shoots, which convey them into a separate receptacle, whence they are carried to the waste-heap. " A point of particular importance for the regular success of the washing process is the thickness of the stone bed lying on the perforated bottom of the washer, and the size and shape of the stones composing it. Experience COAL-WASHING MACHINES. I3S proves that only such minerals as have a specific gravity similar to slate are suitable for the stone bed ; for the current of water vising throu£;h the perforated bottom must have just such a velocity that it holds the slate in suspension, or at the most raises it only a trifle, while the coal, in consequence of its lower specific gravity, is raised considerably. At the same time the stone bed must rise and open readily, so that, on the subsequent receding of the water, the slates, which sink more quickly than the coal, may pass into the interstices of the bed before it settles and closes. The coal, sinking more Fio. 6i. slowly, arrives on the bed only after it is firmly closed, and therefore floats away in the horizontal water-current above. Gradually, as the up and down strokes are repeated, the slates work themselves through the stone bed, and finally pass through the perforated bottom and are carried away. "Luhrichhas experimented with a large number of minerals, and has found felspar to be the most suitable material ; all its physical properties, such as its crystalline form, laminated fracture, hardness, specific gravity (2.5 to 2.6), answer those conditions under which the separation is most perfect. The pieces of felspar, owing to their flattened shape, arrange themselves so that their larger faces are parallel to the direction of the horizontal water-current, and on the receding of the water retain between their sharp-edged side-faces 136 COAL-WASHING MACHINES. the slates entangled in their interstices. After about six weeks' use, the edges of the spar are so much worn and blunted that fresh material has to be put in ; the spar of the nut-coal washers, after crushing and sifting, can again be utilized in the fine-coal washers, while the former are supplied with the fresh material. A perfect separation of the slate, which has a sp. gr. of about 2.3, from the coal of a sp. gr. of 1.3 can be effected only if the particles of coal are kept iloating and the water continually rising and falling. " Experience has proved that with the following dimensions a good work- ing of the apparatus will be secured — viz., for the fine-coal washer, length of stroke 3 to 10 mm., strokes per minute 250 to 200; for the nut-coal washer, length of stroke 40 to 80 mm., strokes per minute 70 to 60. Fio. 62. " About 1000 tons per day can be worked in the plant described- The washed coal contains 3.6 per cent, of ash." Mr. H. Simon, of Manchester, who has introduced this system of coal- washing into Britain, states that the arrangement described by Mr. Baare refers only to one installation, and that there are not two exactly alike of the 150 which Mr. Liihrich has carried out. This is important, because it cannot be expected that any one washing-apparatus or arrangement can prove perfectly satisfactory for all cases. At Bochum, the coal before washing contains 8 per cent, of ash, and after washing ;i.6 per cent., as stated by Mr. Baare. The coke made from the unwashed coal used to contain 10 per cent., but, since washed coal has been used, it contains only 4.57 per cent, of ash. The cost of washing is in this case less than one halfpenny per ton of coal. COAL-WASHING MACHINES. 137 Fig. 61 (p. 135) illustrates the machine made by Sheppard of Glamorgan- shire, which is used in many collieries. It has the advantage of utilizing the same supply of water repeatedly, only that which is absorbed by the coal and dirt having to be made up with a fresh supply. The water circulates in the Fio. 63. Pig. 64. w^ashing-chamber of the machine, and consequently the fine coal is not carried away as in some other machines which necessitate the use of setthng ponds or chambers. A suitable arrangement of elevators is combined with the washer for 138 COAL-WASHING MACHINES conveying the coal to be washed from the hopper or receptacle into which it is shot from trucks, and for raising the washed coal and dirt to their respective shoots, which direct them into trucks. The washer is one of the piston plunger kind, B being the piston which Fio. 66. forces the water upwards through the perforated table C, upon which the coal to be washed is discharged at A. At D the water carrying the floating coal passes over a division, and falls down into the lower settling-chamber G, the coal passing out by the screw A' into the elevator, while the water is drawn by the upward movement of the piston through foot valves at E. COAL-WASHING MACHINES. 139 The dirt passes away from the coal through an adjustable valve at H, and falls into the upper division or chamber F, passing out by the screw B' to its elevator. Messrs. Grant, Ritchie, & Co. of Kilmarnock make the serviceable machine illustrated in Figs. 62, 63, 64, 65. It is a piston washing machine, but has the peculiar feature that the cylinders are placed horizontally, the piston-rods being worked by eccentrics off a shaft driven by belting, or off an extension of the engine crank shaft. The water is forced through the usual perforated table upon which the coal lies, and the washed coal is floated over the edge of the cistern at one end assisted by a revolving fan or kicker. It falls on an inclined perforated shoot, and drops into trucks placed beneath. The dirt accumulates on the perforated table under the kicker, and a plug-valve is there arranged, bj' Fig. 67. raising which the dirt is allowed to drop into the chamber below, from which it is periodically removed in trucks through another valve worked, like the former one, by a lever. A machine designed by Messrs. Kerr & Mitchell, coalmasters, and erected at their Glenclelland Colliery, has also a horizontal cylinder arrange- ment with some interesting features. Figs. 66 and 67 illustrate this apparatus, the speciality of which is the arrangement by which agitation of the water is produced. The usual arrange- ment consists of a vertical cylinder, open at the top, in which a piston or plunger works and forces the water downwards.' In Grant & Ritchie's machine, a horizontal cylinder to each box or tank containing water is adopted the piston acting only on its stroke towards the box. As it is almost impos- sible to keep pistons water-tight, there is some leakage past the piston, and this necessitates a pipe or outlet for this water from the end of the cylinder farthest from the tank. The piston being single-acting, no more than one 140 COKE. tank or box can be served by one cylinder. In Kerr & Mitchell's machine the position of the cylinder is at right angles to that of Grant, Eitehie, & Co.'s, and water is admitted to both sides of the piston, there being an opening to a box or tank at each end of the cylinder. Thus the piston is doing useful work, when moving in either direction, and it is not necessary to expel any leakage water from the cylinder. This construction also makes it necessary to bore out only one cylinder in fitting up two " boxes " or tanks. In order to prevent water running with the washed dross into the waggons and so destroying them, Messrs. Kerr & Mitchell have introduced a revolving riddle, which is placed at the end of the shoot from the washing tank or box. One half of its length is formed, of -^^ mesh, and the remainder of the size of mesh required for good-sized " nuts." The water and washed dross run from the tank down the shoot and fall into the riddle ; the water going through the small mesh is carried away by an inchned shoot or channel placed under this portion of the riddle. The very small coal which escapes with the water is subsequently removed from it by an arrangement of revolving wheels with perforated zinc buckets, and the water passes on to the settling-ponds. Although these machines operate efficiently, yet there are very few in this country which are arranged with the same care as to detail, or so elaborately, as those in Germany, France, and Belgium. Descriptions of the arrangements in use in these countries wUl be found in " Engineering," " Iron," " The Engineer," the " Proceedings of the Institution of Civil Engineers," the " Journal of the Iron and Steel Institute," and other technical works. COKE. For purposes connected with the arts, coke must be compact, in large pieces not liable to crumble and form dust, and it must possess a certain degree of solidity so as to withstand the pressure in smelting furnaces. Both qualities must be considered in the choice of the material selected for its production. Experience has proved that the softness of coke depends to a very great extent on the process employed in making it, and that it may be rendered more compact by judicious management in the coke-ovens. If, for instance, coke is prepared under considerable superincumbent pressure, the blisters which form in the softened coal are pressed together, after the escape of the gases which caused them, and a denser coke is produced ; moreover, long-continued heat tends to render the coke more dense and hard. In order to obtain good coke, caking coal, which approaches sinter coal in composition, should be selected. In the production of coke from the small coal of the northern coal-field of England, nearly every description of caking coal will make good coke, provided the duff be screened out, in which the whole or nearly all of the shale and mineral matter is found. Coke, being much less inflammable than charcoal, only burns well with a good draught, and is soon extinguished in kilns with little draught and in the open air. As the coal from which it is produced is always furnished on the same spot, fewer precautionary measures are requisite in preparing it, and the operation of coking may be easily and most economically carried on in a fixed plant. Produce. — The amount of coke obtained from coal varies with the temperature employed in the manufacture; but, according to Karsten's experiments, the variation is not so great as is observed with charcoal. With wood, nearly double the quantity of charcoal, or 1 2 per cent, more, was obtained by charring at a low heat ; with coal, there is only a gain of 5 or 6 per cent, in coke. More depends here on the quantity of carbon in COKE. HI the coal, the amount of ash that it yields, and the manner in which the elements, carbon, hydrogen, and oxygen, are combined. In consequence of these numerous conditions which aifect the yield of coke, it is extremely difficult, if not impossible, to predict what will be the amount of produce from any given specimen without a direct experiment. The importance of this determination of the amount of coke yielded by any specimen of coal, for its application as fuel in the arts, is so great that vast numbers have been analysed, some of the results of which examination have already been given in the tables at pp. 53-56. We here add a further table, and refer to those at the end of the volume. The quantity of coke obtained from British coals, as examined by the authors of the Admiralty Report, &c. (see p. 56), averages from 54.22 to 72.60 per cent., the ordinary value being the lower. The produce of the American bituminous coals, examined by W. R. Johnson, was from 53 to 76.6 per cent., as will be seen in one of the columns of a table below (see Relative Value of Fuel). The following are the quantities obtained by Karsten from Continental coal, of various districts, distributed according to the usual foreign classification : — Yield : 100 Farts of Coal f rem : Coke. Ash. Fixed Carbon. 3AN a COAL. Caroline . 65.6 2.8 62.8 Charlotte • • ■ 67.5 2.42 65.08 Upper Silesia 1 Beate . 66.8 II. 9 54-9 Theodor . 53-5 1-9 51.6 Josepha . ■ 56-9 3-4 53-5 Lower Silesia - Laura . 70 i.8s 68.15 u • 73-5 2.4 71. 1 1 Fuchsgrube 59-1 2.1 57 Saarbriicken Geislautem . 62.1 3-9 58.2 England . Cannel coal . . 69.8 133 56.5 Brazils . 59-5 1.6 57-9 ,, . 66.5 28.4 38.1 SINT ER COAI.. Konigin Louise . 67 1.2 65 Upper Silesia • KiJnigsgrube . Henriette ■ ■ • • ^5-3 • 63.8 0.6 1.65 64.7 62.15 Treue Caroline . . . . 61.5 4.8 56.7 David . . 68 2 66 Lower Silesia • Louise Aiiguste Frischauf . 66.5 . . . . 78.8 1-3 23-4 65.2 55-4 )? • 73 8 65 Prinz Wilhelm . 62.1 1.3 68 Saarbriicki'n . Merchweiler . . 61.88 0.9 60.98 Gerhardgrabe . 58.5 1.6 56-9 Saxony . Planiiz (Pechkohle) 64.5 I.I 63-4 CAKIN COAT.. (■Friedriuh zu Zawada 60 2.1 57-9 52.7 Upper Silesia ] Sackgrube zii J'^zerni tz_ . . . . 58.5 5.8 (Stollenflotz zn Hulls chin. . . .86.9 2.1 84.8 62.15 [Gnade Gottesgrube . . ' 66.8 4.65 Lower Silesia ■ ^"uethfl^rube '. : . : • tV 1-9 0.8 68 ^ 67.2 (Kombiniite Abendro the . . . .7? 4.9 70.1 63-85 64.15 64.6 Sulzbach Duttweiler . . 64 0.15 Saarbriicken • Friedriohstbal . . 64.8 0.65 (Wellesweiler . 65.6 I 143 COKE. YIELD OF COKE FROM CONTINENTAL COALS — continued. Yield: TOO FartB of Coal from : Coke. Ash. Filed Carbon. OAKiNQ COAL — Continued. Wettin .... ■ • 78 10.8 67.2 Saalkreis )>•••* 81. 1 24.4 56-7 77-5 5- 1 72.4 FnrnagelflOtz . 80 1-3 78.7 Bsohweiler . Schlemmerichflotz . 84.5 3-25 81.25 Fliitz-Gyr ti-5 1. 17 80.33 Iliitterbank 86.3 I 85-3 Westphalia . Salzer und Neuack . 82.3 0.7 81.6 Stock und Scheereuberg . 80.1 0.65 79-45 Cannel coal . 5« 0.5 50.5 England j> ^i-5 5- 5 1^ Newcastle .... 68.5 0.85 67.65 Saxony . Pottschappel (Gute Schicht) . 68.7 27.7 41 [Barg-Lastic . . 82.9 5.8 77.1 ^-- ■ FoTary! : • : R8 ■3-5 7.2 71-5 71-5 (.Creuzot . ... 68.8 3-4 65.4 ANTHKACITE SISTER COAI,. Upper Silesia Therese zu Hultschin .... 88.4 2.66 85-74 Saalkreis .{LSbejun . . 89.1 90 9-1 20 80 70 Tiirteltaube . 86.8 2.4 84-4 Westphalia . - Louisen- ErbstoUen . Sperling . Hamburg 72.8 85.5 89.1 1-4 3.5 0.9 71.4 82 88.2 Belgium . IVlons ... 88 2.5 85-5 ANTHRACITE SAND COAL. Neu Langenberg ... 93-6 0.8 92.8 Principality of Hoheneich . 94.8 1.2 93-6 Badenberg Furth . 95 0.7 94-3 .Abgunst 96.4 1-75 94-65 Saalkreis J Lbbejiin . 92 90 7 9-9 f5 80.1 Alter Hase . 92.5 1-7 90.8 Westphalia . Hupdsnopken . 92.8 0.6 92.2 Schwarzer Junge .... 91.9 I.I 90.8 If the percentage of coke obtained from the pure organic portion of the coal (that is, the ash deducted) be calculated from the tables above, and com- pared with the actual quantity of carbon contained in the coal as deduced from former tables, we shall find the following relations : — Actual carbon contained in coal per cent. Coke produceable from coal per cent. Sand coal ...... Sinter coal Caking coal . . ... Anthracite sinter coal Anthracite sand coal J ' 75—80 80-85 85-90 90—95 55-65 60—70 60—80 85-94 Regnault has shown, however, that the percentage of carbon in the coal is not always a correct indication of the quantity of coke that it will yield, and that greater differences in coke-produce, even than those stated above, occur in some varieties of coal. It is proved, therefore, both by theory and NATURE OF COKE. 143 experiment, that no certain amount of coke-produce can be obtained from a coal of a known percentage of carbon ; the only safe criterion, on which every large consumer of coke can base his calculations, must be the mean actually obtained from a large number of coking operations. Still, as will be observed, the amount of coke does, on the wJwle, rise with the actual amount of carbon present in the coal. The annual average, from observations made at Rive de Gier, was 69 per cent, coke; with inferior coal and less care, not less than 60 to 65 per cent, were obtained ; whilst coal and pit-dust in the heap yield only 45 to 50 per cent. ; and in the ridges, rich coal yields 40 to 45 per cent. Coal containing little hydrogen produces ^ more. General experience has shown that the oven produces denser coke than the heap; and this, again, coke more dense than the ridges; and yet the coals in the two latter cases scarcely yield their own volume, whilst in the ovens this increases in the ratio of 10 : 12. On the other hand, the smelters find the coke from heaps and ridges much more free from sulphur than that made in ovens. Nature of Coke. — The physical appearance, as also the chemical con- stitution of coke, varies with the nature of the coal from which it has been prepared and with the mode of its preparation. It is generally a, highly porous vesicular mass, varying in colour from a blackish -grey with a more or less fatty lustre, in that prepared from coal rich in oxygen, to a light iron-grey with a fine silky or almost metalKc lustre, in that obtained from caking-poal, which has much resemblance in structure with a mass of melted slag or lava. A play of colours is often observed in some varieties of coke, and is indicative of the presence of sulphur, in the form of very thin layers of ferrosoferric sulphide. Good coke should be uniform through- out, without any great admixture of fibre coal or shaly matters ; it should be dense and compact. Coke, like charcoal, attracts moisture from the air, often as much as 30 per cent., and it is said — but probably on very in- adequate authority — to possess greater heating power after having been kept for some time. Too much exposure to the weather renders it soft and liable to crumble. The amount of ash depends, of course, on the amount contained in the coal, and is greater, the smaller the proportion of coke obtained. The following selection of analyses will give some idea of the composition of the different cokes used in this country : — I. 2. 3- 4- 5- 6. 7- 8. 9- 10. Carbon Ash . Sulphur 95-51 2.85 1.64 85.85 12.07 2.08 90-53 8.46 1. 01 9421 5.10 0.69 93-41 5.80 0.79 93-05 5-37 1.58 S9.87 8.35 1.78 84.82 14.40 0.78 96.42 2-75 0.83 97.60 1-55 0.85 100.00 1 00. CO 1 00. CO 100.00 jioo. 00 |ioo.oo jioo.oo 100.00 100.00 100 00 II. 12. 13- 14. ■5- 16. ■7 18. 19. Carbon Ash . Sulphur 94.08 5.04 0.88 92.44 6.O0 1.56 8969 8.35 1.96 91.16 76s 1. 19 93-54 5.70 0.76 91.49 7-05 1.46 9431 4-97 072 94.67 4.26 1.07 92.70 5-70 1.60 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100.00 100. CO Storer and Lewis find that air-dried coke contains occluded gases, in the proportion of about 0.7 c.c. per gram ; the gases consisting of 50 to 60 per cent, of carbonic acid, and 2 to 6 per cent, of oxygen. The percentage of carbonic acid increases on keeping. In snlelting operations, it is of great importance that the coke should be 144 NATURE OF COKE. hard burnt, so as to be dense and capable of resisting the action of the blast, and also, as pointed out by Sir I. Lowthian Bell, the solvent action of the carbonic acid which passes up through the furnace from the tuyere region, so that solid coke may come down to the tuyeres in order to produce the requisite temperature there. Coke of this quality carries twice the burden of ore, and produces — in iron-smelting, for example — a metal of a verj superior quality. The nature of the ash is, however, of less importance in smelting than in the locomotive, where the quantity is not so serious an objection, provided it does not scar, so as to obstruct the draught; hence 3ome cokes, which contain a large percentage of white ash, as No. 2, are preferred to those which have a much smaller quantity of ash, but of a kind which melts on the grate-bars. Great importance is attached to the bright, silvery, metallic appearance of the coke ; and some experiments were made three or four years ago to improve this property, by dissolving common salt in the water with which the coal was moistened, but without effect. The preparation of coke is a very extensive trade in this country, in consequence of the increasing demand for it ; and the small of coking-coal, which was formerly of comparatively little value, has, in consequence of its peculiar adaptation to the production of coke, become a most important source of profit. So superior, indeed, is the coke made from small coal, both in density and strength, that it is usual now to grind or partially grind the coal for coking, and washing is always resorted to also where the coal contains a notable proportion of. shaly or other mineral matter. There is some difference as respects the management of different qualities of coal in converting them into coke. The great object of the coke-maker is to pro- duce a dense, compact coke, in such large masses that in cases of long carriage, either by sea or land, these lumps may arrive at their destination without being broken up into such small pieces as to be unfit for use. This object is most effectually accom- plished by burning large quantities of coal of sufficient depth to ensure long upright masses of coke in the oven at the end of the operation. But some coals, which contain a large percentage of ash, form a coke which melts easily, and when the ovens are charged with too deep a load of such coal, the coke melts, and covers the upper layers in such a manner that the .air cannot penetrate to the unbumt coal at the bottom of the oven, and the produce is a mixture of charred coal and coke. On the other hand, when coal contains a large proportion of ash, which does not melt in coking, the same result is observed. This arises, however, from a different cause ; the mass of coke at the top which is first formed continues to bum, leaving its ash on the sur- face, and, this accumulating, at length falls down into the crevices, and chokes the fire before it has time to reach the bottom layer of coal ; thus, in Fig. 68, a is the unbumt coal, h that partially coked, c the coke already formed, and d the ashes which have fallen down, and prevented the access of air to support the combustion. In such cases, the difficulty in the coking process is obviated by building smaller ovens, and loading them lightly, or by coking by means of external heat applied to the ovens, as in the Appolt or Coppee forms of oven. POKOSITY OF COKE. 14S When suitable coal exists, the advantages of heavy loading are very obvious. The whole mass of coke is longer exposed to the hardening effect of the fire, and the heavy products of distillation, ascending from the bottom layers of coal, deposit large portions of their carbon on the side of the already formed coke, thus increasing the produce from a given quantity of coal. The ovens about to be described are now generally constructed to contain from 7 to 10 tons of coal, and produce a most superior coke, both as respects quaUty and quantity. After the oven has ceased to burn, the whole is made perfectly close, and the coke, kept in the heated state for some time, contracts in bulk, and becomes much harder and more compact. In coke intended for iron and other smelting operations, where it is exposed to the action of a blast, long before it really, does any eificient duty, the above qualities are most valuable. The Porosity and Specific Gravity of Coke. — In all metallurgical operations which do not depend on the production of a flame for their efficiency, coke is acknowledged to be the best fuel known ; it therefore becomes desirable to ascertain on what its superiority depends. The prin- cipal operation for which it is used is the production of pig iron in the blast furnace, and this section will be chiefly devoted to the consideration of the characteristics and advantages of coke as a blast-furnace fuel. Apart from its chemical composition, the prime requisites of such a metallurgical fuel are that it should enter into combustion with facility at the proper time and in the proper locality within the furnace, so as to pro- duce the requisite temperature ; moi-eover, it should be physically strong enough to withstand the mechanical strain to which it is subjected during its descent with the charge in the furnace. These two characters are of equal importance, and neither can be sacrificed for the other, as is well illustrated by the three fuels charcoal, coke, and anthracite. Taking the best examples of each kind, the three fuels charcoal, coke, and anthracite form a series in which the first, charcoal, readily enters into combustion and furnishes the proper temperature, but it cannot withstand the mechanical effects of the charge in more than a moderately high furnace, so that, were it not for its freedom from ash and consequently its yielding an iron of exceptional purity, it would scarcely be used for the manufacture of iron except in regions remote from other fuels. The last, anthracite, is well able to withstand the mechanical effects of the charge in the highest of furnaces, but its rate of combustion is slow, and therefore it does not readily give the necessary temperature. The middle member of the series, coke, combines the good qualities of both the others, while the in- jurious qualities are reduced to a minimum in that it ignites with ease before the tuyeres, yielding the proper temperature ; at the same time, it is able to withstand the weight of the charge in the highest furnaces. If we examine the following analyses. Water. Volatile Matter. Fised Carbon. Ash. The average of i4analy6esof Swedish charcoal „ „ 2 „ Pennsylvania coke „ „ 30 „ „ anthracites 5.48 0.52 3-39 6.72 0.436 3-8i 86.4$ 89. 1 1 8379 1. 12 9. 58 8.42 we shall see that the principal chemical difference between the charcoal and anthracite lies in the smaller percentage of ash in the former, which gives it a great advantage in the purity of the product manufactured by its use, while the coke possesses a. higher content of the most valuable fuel constituent, fixed carbon, and is also higher in ash than either of the others. 146 POROSITY OF COKE. With the exception of the ash, the differences in composition of the three fuels are small, and small as they are they are still further reduced in the hot upper portions of the stack by the loss of their water and volatile matter, so that, when the three fuels reach the region of the tuyeres, the only chemical difference between them is the difference in the amount of ash they then contain; we are forced to the conclusion, therefore, that the great differences in the use and the results obtained by the three fuels cannot depend on the slight differences in their chemical composition. If we examine the physical structure of the three fuels, we shall find very great and marked differences, and on these differences depends almost entirely the superiority of coke. As described by Svedelius : " Properly made charcoal retains distinctly the texture of the wood from which it is made, although its colour is black and it has a glossy fracture, it floats upon water, it will sustain quite a heavy weight if gently laid upon it, but breaks easily by a light quick blow," and " by boiling ordinary good charcoal in water, we may increase its moisture to a very considerable extent." Although it is so soft and friable that it can scarcely come into contact with any other body even very gently without leaving a black mark, yet when sharply struck with a hard body it emits a feebly ringing sound. The ease with which charcoal enters into combustion is well known, and depends partly on its softness, and partly oa its porous nature, as shown by its ready absorption of water. This ease of combustion is one of its chief advantages in smelting iron, but at the same time it places a limit to its use, in that its friable nature and the facility with which it breaks when struck quickly would cause it to be crushed to powder and carried away by the ascending current of gases in the form of dust, long before it could reach the region of the tuyeres, if used in furnaces of large size and output, and even if it were not thus crushed it would tend to enter into combustion before reaching the region of the tuyeres in such large furnaces, and thus produce abnormal results by the undue heating of the upper portions of the stack; its use, therefore, is confined to furnaces of small size and output, 55 feet being the maximum height and 60 tons a day the maximum output, although the average is very much smaller than this. Anthracite is of a hard, dense, non-porous structure, and of suffi- cient strength to bear the burden of the largest furnaces ; its denseness, however, is a great drawback to its rapid combustion at the tuyeres, as it offers but a limited surface for the hot oxygen of the blast to act on, and at the same time, carbon being a non-conductor for heat, the inner portions of the pieces are only slowly heated by the ascending current of hot gases during the descent of the charge within the furnace; consequently, in order to bring the temperatura of the coal to the proper point for active combustion much valuable heat is absorbed in front of the tuyeres just where it is most needed to perform useful work. It is claimed by some that the tendency of anthracite to decrepitate, when heated, makes up in a measure for its denseness, by breaking it up into small pieces, which offer more surface for the blast to act on, and are also more readily heated, on account of their smaller size, by the ascending current of hot gases, both these conditions aiding its rapid combustion at the tuyferes ; on the other hand, it is thought by some that this tendency to decrepitate is injurious rather than beneficial, as it produces dust and thus clogs the flues and gas ways ; be that as it may, anthracite is still far from being the equal of coke, the maximum output accomplished by its use being 90 tons per day. When we examine a piece of coke of good quality, we find that it has a bright, silvery lustre, that it is hard and does not readily yield to pressure. POROSITY OP COKE. I47 that when sharply struck it gives a clear ringing sound, but above all we are impressed by its open and porous nature, we see that it is permeated by the ramifications of a compKcated and extensive system of inter-opening pores. It is this porous structure which gives coke its great advantage as a metallurgical fuel, and is its prime requisite, so that, in a general way, the more porous a coke is the better it is ; but there is a limit to its porosity, and that is the strength of the pore walls, for when the porosity is developed to such an extent that the walls are rendered so weak by their distention that they can no longer bear the burden within the furnace, but begin to crush, then the porosity has reached its maximum beneficial development, and any further increase is injurious rather than beneficial. This limit to the porosity will of course vary with different coals, and in some cases may be overstepped, although the actual percentage of pores is small, while in other cases it is not reached until the percentage of pores becomes very large. Where this limit to the porosity is passed in the ordinary working, it becomes necessary, in order to produce a sufficiently strong coke, to change the course of the operation in order to arrest or modify the development of the porous structure. This is well illustrated in some recent experiments at Trzymetz in Silesia, where a coal, which under ordinary circumstances refused to coke at all in the Gobeit ovens, was made to yield a coke of fair quality by being crushed and then submitted to hydraulic pressure before being introduced into the ovens. The effect of this porosity within the furnace is very easily explained. As the charge descends within the furnace, little or no resistance is offered to the free entry of the hot gases of the ascending currents into the body of ■each piece of the coke, so that they soon become thoroughly permeated to their very centres with these hot gases, which readily impart a portion of their surplus heat to the coke, and this becomes hotter and hotter until, finally, when it reaches the very hot air of the blast in front of the tuyeres it has -already acquired such a temperature throughout that its combustion is very much aided. At the same time, it offers such an enormous surface for the hot oxygen of the blast to act on that it enters into combustion very rapidly indeed, and thus furnishes the high degree of temperature necessary for the rapid and successful working of the furnace. Notwithstanding the ease, therefore, with which the coke enters into com- bustion when properly prepared by this preheating, its carbon is very hard and dense, and does not ignite readily or at all in the cooler upper portion of the blast furnace, thus avoiding the derangement of the furnace by the undue heating of these upper parts. In the application of coke to the smelting of iron, the maximum height •of furnace employed is 90 feet, but the most productive furnaces are some- what shorter than this. The " D " furnace of the Edgar Thompson Steel Go. at Bessemer Station, Alleghany Co., Pennsylvania, measures 80' by 20', and has reached the enormous output of 299 tons of 2268 lbs. in twenty-four hours ; while this, of course, is excessive and very unusual, it has averaged over 230 tons of 2268 lbs. per day for a month at a time. There are many coke furnaces measuring from 60' to 80' by from 16' to 20' which average from 125 to 150 tons per day. That the rapid and economical working of a furnace is largely dependent on the facility with which the fuel burns is indirectly, but on that account all the more clearly, indicated by the great change which has taken place in the ideas of furnacemen during the last few years in regard to the method of running the blowing engines of the furnace. It was formerly held that the chief condition of the blast outside of its temperature was the pressure under which it entered the furnace, but now the chief condition is regarded as being the revolutions of the engine per minute, or rather the quantity of 148 POROSITY OF COKE. air which is going into the furnace, the more revolutions or the more air going into the furnace the larger the output, the other conditions remaining favourable. In other words, this means that the faster the fuel can combine with the oxygen of the air in front of the tuyeres, thus allowing a larger amount of air to be driven into the furnace within a given time, the greater the output will be, the other conditions remaining favourable. The above remarks are based on the consideration of the best typical examples of each class of fuel. When we consider the different qualities of each fuel, it will, of course, be found that poor grades of coke fail to accom- plish as much as the better grades of the other fuels. The method of manufacturing coke is very crude and wasteful, and there has been very little real improvement in it for many years, although there have been many attempts to introduce new and improved methods, and especially in the direction of means for saving and utilizing the bye- products which are now allowed to go to waste. This failure is due to two causes — first, the lack of exact information as to the true nature and characteristics of a good coke and the behaviour of different coals under varying conditions of manufacture ; and, second, the perverse conservatism, not to say prejudice, of furnace managers, who refuse to give a coke, differing in outward appearance or in the method of its manufacture from what they are used to, a fair and impartial trial in their furnaces As at present understood, and in the present mode of manufacture, the essential characteristics of a good coking coal are that it shall contain not less than 20 nor more than 30 per cent, of volatile hydrocarbons and not too much ash ; that on being heated it must pass through a thoroughly fused or pasty condition ; and that when in this condition it must part with its volatile matter in such a manner as to form innumerable small pores. If a coal contains less than 20 per cent, of volatile matter it will not fuse properly, whilst if it has more than 30 per cent, the porous structure will be unduly developed at the expense of the strength of the pore walls ; on the other hand, many coals lying between these limits will not fuse at all, and therefore do not coke, while others fuse properly but give off their gas so as to form large and thin-walled pores. A coal occurring at Soddy, Hamilton Co., Tennessee; containing 27.8 per cent, of volatile matter expanded so much in coking that it ruptured the ovens as at first constructed. The ordinary methods of making chemical analyses of coal are very unsatis- factory, inasmuch as they fail to show anything whatever of the manner in which the elements are combined, whilst the ordinary statement of an analysis is extremely vague, so that there is great room for improvement in this direction, and improved methods of analysis will undoubtedly open the way to a better understanding of the coking process and facilitate improve- ments in the methods of coking. The coking takes place in ovens of the typical beehive pattern, of varying size, but mostly of less than 6 or 7 tons capacity, an(J is accomplished by the combustion of a portion of the coal itself as well as the volatfle matteis given off during the operation within the oven. It is very essential that there should be no hindrance to the ready escape of the volatile matters, and one of the prime causes of the failure of many of the attempts to save and utilize these volatile matters is the fact that they do unquestionably interfere with the easy expulsion of the volatile material of the coal. This necessity for a free evolution of gas has also limited the size of the beehive oven, as well as interfered with the use of other styles of oven. As soon as pressure within, developed either by an obstruction to the escape of the gases or the weight of the upper portion of a high or deep charge upon the lower portion of the charge, is brought to bear upon the coal in its fused condition it is compressed, and the resulting DETERMINING THE POROSITY OF COKE. 1 49 coke is dense and not porous. This is to be seen plainly in the coke made in the old style Coppee oven, where the upper layers are much more open and porous than the lower ones, which not only had to bear the burden of the upper layers of material, but were also subjected to a stronger gas pressure. "Whilst this condition of the free evolution of gases is undoubtedly neces- sary in the treatment of coals which produce a first-class coke in the beehive oven, yet it may well be that a suitable pressure applied to the before- mentioned Soddy coal at the proper time might greatly improve the quality of the coke produced by lessening the size of the pores, and consequently increasing the thickness and strength of the pore walls ; and the same may be true of other coals which produce an inferior coke in the beehive oven. The practical method employed by furnace-men and other? to determine the relative value of two cokes is to judge by the eye as to the relative porosity, and, if found satisfactory, then to take t^yo pieceg of about the same size, each having an approximately ilat surface, and rub them together violently for a few moments ; the one which appears to suffer the least by this treatment is pronounced the best coke. This, of course, is a very crude and unsatisfactory way of testing, as almost everything depends on the judgment of the tester, which may or may not be influenced by other considerations; it shows, however, an appreciation of the two essential charac- teristics of a good coke, and has had a value, notwithstanding a more accu- rate and refined method of testing was very much needed. When the physical characters of coke shall have been fully and carefully determined, and the behaviour of coking coals under varying conditions thoroughly investigated, so that there is some basis of scientific fact upon which to found new and improved methods of coking, there will be far more probability of success rewarding the efibrts of those who are working to that end. Mr. Dewey has made a beginning in this direction by determining the porosity and specific gravity of a series of American cokes, which, however, is not yet completed, but is being carried on as rapidly as possible in connec- tion with other investigations of coke and coal. In determining the porosity or space occupied by pores in any given body there are two methods wbich have been used, mostly in the investiga- tion of rocks and principally those that have been used for building purposes. The older and more generally up<'d method is to cut an accurate cube, generally a cubic inch, of the material, dry it thoroughly, weigh, fill its pores with water and weigh again ; by a simple calculation the excess of the second weigiit over the first will give the volume of pores in a cubic inch of the material. Thp great objection to this method is the time, care, and attention necessarj in cutting an accurate cube, and in the case of coke, owing to its very porous nature, the difficulties are greatly increased. A far easier, neater, and in every way better method, and one that at the same time yields good results, is that proposed and used by Sterry Hunt in the Report of the Geological Survey of Canada, 1863-6, pp. 281-3. This method is to select suitable specimens of any size or shape, generally between 20 and 40 grams in weight, dry and weigh them, then fill their pores with water and weigh in water ; the pieces are then taken out of the water, the excess of water upon their surfaces carefully removed, and weighed again in air. These three weighings furnish all the 4^^ necessary for cal- culating : — I The apparent specific gravity, or the relationship between the whole ma»s of niateiial and an equal volume of water. J I. The true specific gravity, or specific gravity of the particles. ISO DETERMINING THE POEOSITY OF COKE. III. The volume of pores in loo volumes of material, or percentage of pores by volume. IV. The volume of pores in a given weight of material, as c.c. in loo grams. The loss in weight of the material saturated with water when weighed in water, being equal to the volume of water displaced by the mass, enables us to determine the specific gravity of the latter ; while this loss in weight, less the weight of the water absorbed by the mass, gives the true volume of water displaced by its particles, and hence the means of determining their specific gravity. The division of the amount of water absorbed, by the amount of water displaced, gives the amount by volume of the pores in a unit of the material, and the division of the weight of the water absorbed, by the weight of the dry mass, gives the volume of pores in a unit of weight of the material ; let a = the weight of the dry material, b = the weight of water which the material can absorb, c = the loss in weight, in water, of the saturated material. Then— c : a :: looo : x = the apparent specific gravity, or the specific gravity of the mass, c-b : a ;: looo : x = true- specific gravity, or specific gravity of the particles, water being looo. c : b :: loo : a; = percentage by volume of the pores in the material, a : b ;: loo : a; = volume of pores in loo parts by weight of the material, say c.c. in loo grams. In experimenting with coke, it was found necessary to make several changes in the usual proceedings on account of the nature of the material,, and the method adopted was as follows : — Suitable specimens from 20 to 40 grams in weight were selected to re- present the average physical condition of the coke. They were thoroughly brushed to remove any loosely adhering particles which might fall off during the experiments, and thus vitiate the results, and were weighed just as they were received; tliey were dried at a temperature of 100° C. for one hour, cooled under the desiccator and weighed, the loss in weight representing- the amount of moisture found in the specimen as received. Great difiiculty was experienced in thoroughly filling the pores with water, on account of the small amount of adhesion between the surface of the coke and the water, but, after considerable experimenting, the following general plan was adopted, which was modified in its details to suit particular cases. In filling porous substances generally with water, two methods are in use — one to soak the specimens in water for a time and then to place them in water under the receiver of an air-pump and exhaust until no more air is given off J and the other to keep them suspended in boiling water until the pores are filled with water, as is shown by their ceasing to gain in weight on taking them out, cooling, and weighing. In this case, it was found more expedient to use a combination of these two methods. The specimens were placed in water and allowed to remain from twelve to twenty-four hours ; they were then placed under the receiver of an air-pump and the air ex- hausted, the exhaustion being repeated from three to five times. The specimens were then removed and placed in boiling water and boiled for three hours. After becoming nearly cold they were again placed under the receiver of the air-pump and exhausted, and the exhaustion repeated at intervals of ten to twenty minutes, until no more bubbles were seen to come DETEEMINma THE POEOSITY OF COKE. 151 off ; as a precaution, they were further exhausted from six to eight times to insure the removal of the air as completely as possible. Owing to the nature of the case, it is not possible to replace the very last traces of air by water, and, in order to detei-mine the probable error from this cause, eighteen specimens were again subjected to a varying number of exhaustions, amounting in one case to twenty, and it was found that the average gain in weight represented only 0.34 per cent, of the true volume of the coke experimented with, an error sufficient to cause but a vei'y slight difTerence in the results. The specimens, now thoroughly saturated with water, were weighed first in water and then in air. The directions laid down by Dr. Sterry Hunt, and the plan generally followed in determinations of porosity, to dry the surface of the saturated specimens with bibulous paper or some other absorbent of water before weighing in air, could not be followed in this case, for, owing to the large percentage of pores in the coke, and to the sUght adhesion of water to their surfaces, it was found that, on applying any absorbent material, the water would not only be removed from the surface, ■ but with- drawn from the pores themselves. It was therefore decided that the most feasible plan would be to remove the specimens from the water and allow as much water as would to drain off; they were then weighed as rapidly as possible. Although in this way a double error is induced — first, a plus error from the thin film of water adhering to the surface of the coke, and, secondly, a minus error from the water flowing out of the pores opening upon the surface, these errors will, in a measure, balance each other. It is necessary to take this last weight as quickly as possible, for the evapora- tion from the surface of the coke is very rapid, and it takes but a few moments for a specimen to lose 10 mg.^ — in fact, during the time necessary to change ',the rider on the balance a specimen will sometimes lose as much as 5 mg. In order to determine the probable error of weighing these wet specimens, thirty-three specimens were weighed and again immersed in water, and after standing twelve hovirs were taken out and weighed again. Of these thirty-three specimens, twenty-five gained weight and eight lost, the average gain being 0.14 per cent, of the total volume of the coke, and the average loss was o. i per cent. In the deteimination of the specific gravity, there are two sources of variation, one inherent in all specific gravity determinations and unavoid- able, and the other accidental and in a measure disappearing in the averages. The first error is due to the possible presence of water-tight pores, or cells, causing a minus error in the determination. The other error is due to the possible presence in a piece of coke of a small piece of slate, causing a plus error. The first or minus error applies also to the porosity determination, but its efiect is far less in that case than it is on the specific gravity determination, for in the first case the result is only aflfected by the actual volume of the water-tight cells, whilst in the second case, apart from this, the determination is affected by the buoyancy imparted to the specimen by the inclosed air or other gas. The crude and varying conditions under which coke is made naturally tend to produce material of varying characters and qualities, so that among the many needed improvements may be mentioned the produc- tion of coke of uniform characters and qualities. For improvements in this direction, so far, reliance has been placed on the experience of the workmen gained from long use of the same coal. Under the most favourable conditions, no one piece of coke can be said to represent one charge of the oven, and much less can it represent the general run of the oven or a set of ovens. In experimenting, it is desirable to select as many 152 SPECIFIC GRAVITY AND POEOSITY OF COKE. pieces as possible to represent any particular coke; Mr. Dewey usually takes twelve. Differenee.s amounting to 0.236 in the apparent specific gravity, 14.88 per cent, in the percentages by volume of cells, and 33.81 c.c. in the c.c. of cells in 100 grams of coke have been found in the product of the ovens of J. F. Dravo at Connellsville, Pennsylvania, where special efforts have been made to secure uniformity of product. In carrying out this investigation, 153 specimens of coke were exa- mined, representing eleven localities producing metallurgical coke, and one gas-works coke; in all cases but one, twelve specimens were selected to represent the locality ; the exception, Uonnellsville, was represented by twenty-one specimens. The results given are reduced to the temperature of the maximum density of water (4° C), and embrace the maximum and minimum determinations in each set, and also the average of the twelve determinations of the following points: — Moisture; true specific gravity, or the actual specific gravity of the coke; apparent specific gravity, or the relationship between the whole volume (including the coke and the cells) and an equal volume of water ; the percentage of cells by volume, and the volume of cells in a given weight of coke (cubic centi- metres in 100 grams). It must be borne in mind, however, that although the determinations are given in a line for convenience, yet it does not follow in every case that related results are obtained from the same specimens — that is to say, while in some cases the maximum apparent specific gravity and the minimum percentage of cells given are the results obtained from the same specimen, yet it is not always so ; for, in following out the relationships between the results, it is necessary that all the deter- minations of a specimen should be taken into consideration, and in some cases the results obtained from different specimens, in one or more deter- minations, will agree within the probable error of determination. The most important and best developed coke region in America is the section of country about Connellsville,' Fayette Co., Pennsylvania, and the product of the Connellsville ovens has a very high reputation over the whole country, so much so that there is scarcely an important metallurgical centre to which it has not at some time penetrated, its intrinsic worth being aided in this direction by the very low cost of production. The ovens, of which about 10,000 are in operation, manufacture coke mainly for sale in the open market, only a small proportion of them being controlled by iron-making concerns who make and use their own coke The region occupies a small separated basin in which the Big or Pitts- burgh seam of coal reaches a remarkable development and a change in character, which renders it more suitable for the manufacture of coke than at any other place in the State. The mining of the coal is very simple and inexpensive, and the details of the manufacture have been so systematized and cheapened that coke is sold at a very low rate at Connellsville. The oven in use at Connellsville is of the typical beehive pattern, 1 1 to 12 feet in diameter, and 5I to 6 feet in height, and has not been materially changed for over half a century. The time occupied in the coking operation is usually forty-eight hours, or two days, while seventy-two hours, or three days, are allowed for the charges that would otherwise be drawn on Sunday. Occasionally twenty-four hour, or one day, coke is made. The seventy-two hour coke is regarded as being much the best. The chemical composition of the coal and coke is represented by the following analyses : — SPECIFIC GRAVITY AND POROSITY OF COKES. 153 COAL. Broadford. Lump. 1 Slack. Water Volatile matter . Fixed carboii Sulphur Ash . . . Total Colour of ash Coke, per cent. Analyst . 1.260 30.107 59.616 0.784 8-233 0.950 29.662 55.901 I-931 "•556 3- -36 59.62 0.784 823 100.000 100.000 99.994 Reddish grey 68.633 A. S. McCreath Rtddish grey (>9.388 A. S. iVJcCreath. T. T. Morrell COKE. Broadlbi-d. J.F. Dravo. J. P. Iiravo. Water . Volatile matter . Fixed carbun Sulphur Ash Total Analyst 0.030 0.460 89.576- 0.821 9-I13 0.040 0352 88.936 0.771 9-93' 0. no 0.471 88.403 0.838 10.178 87.46 0.69 11.32 87.26 0.746 11.99 100.000 100.000 100.000 - A. S. McCrealh A.S.McC. A.S.McC. - To represent this region twenty-one specimens were selected. A series of nine specimens from the Broadford Works of Frick & Co., taken from a shipment to the Crozer Furnace at Roanoke, Virginia, yielded the following results : — COKE. CONNELLSVILLE, BROADFOBD — FRTCK AND CO. Moisture. True Specific Gravity. Apparent Specific Gravity. Per Cent, of Cells by Volume.. c.e. in 100 Grams. Maximum . Minimum . Average 0.096 o.ooS 0.034 >-79 1-033 1.73 0.819 1.76 ' 0.892 54-37 42.20 49-37 66.31 40.83 55-73 A series of twelve specimens, three samples being taken from each one of the following works — i, Morrell ovens; 2, H. C. Frick 6 1.69 0.891 0.750 0.703 55-79 46.41 ' 53-19 74-30 52.08 67-39 Lower Measures coal (XII. of Rogers' Survey) is coked at Stone Cliff and Fire Creek, Fayette Co., West Virginia, for sale in the open market. At Stone Cliff, the beehive ovens are 1 1 feet 6 inches by 6 feet, the charge being 9000 pounds for forty-eight hour and 10,000 for seventy-two hour coke. At Fire Creek, typical beehive ovens are used, and the coal and coke are of the following compositions : — Coil. Colce. Coke. Moisture 0.61 0.260 0.1 1 Volatile matter 22.34 0.260 0.3s Fixed carbon 75.02 92.377 92.18 Ash . . 1-47 6.750 6.68 Sulphur 0.61 0-535 0.618 Phosphorus . — 0.0146 0.027 Analyst — H. Froehling J. B. Britton Twelve samples from each of these localities yielded the following results : — COKE. — STONE CLIFF, NEW RIVER DISTRICT, FAYETTE CO , W. VIRGINIA. Moisture. True Specific Gravity. Apparent Specilic Gravity Per Cent, of j Clls by 1 '■=■ '" '°° Volume. ! l^™'"^- Maximum . Minimum . Average (12) O.I 19 O.OJ9 0.074 1-79 1.66 1-74 0.962 0.740 0.838 57.60 46.20 51-79 77-85 50-14 62.30 COKE. FIRE CREEK, NEW RIVER DISTRICT, FAYETTE CO., W. VIRGINIA. Moisture. True Speciflo Gravity. Apparent Specific Gravity. Per Cent, of Cells by Volume. c.e. in loo Grams. M 'ximum . Minimum . Average (12) 0.161 0.024 0.07S ' 1.88 1.78 1.83 0.897 0.554 0.820 70. 10 49 99 55-12 126.58 55 74 69.05 Upper Measures coal is coked at use in the blast furnaces located there, position : — Rockwood, Roane Co., Tennessee, for The coal is of the following com- Water Vcilatfle matter . Fixed carbon Ash 1-75 26.62 60. 1 1 11.52 100.00 •■49 . F. P. Dewey. ... M 1-39 32-59 60.75 527 Total . Sulphur Analyst 100.00 M. Duncan SPECIFIC GEAVITY AND POROSITY OF COKES. IS7 This coke was made in beehive ovens, ii, 12, and 13 feet diameter, and 6 feet high, the charges being 100 bushels and the coking occupying forty- eight hours. It is used in the two furnaces of the Roane Iron Company at Eockwood, 65 by 16 feet and 65 by 14 feet, and carries a burden of 2.29 pounds to I pound of coke. A series of twelve specimens yielded the following results : — COKE. — ROCKWOOD, TENNESSEE. Moisture. True Speoifie Gravity. Apparent Spedflc Gravity. Per Cent, of Cells by Volume. c.c. in TOO Grams. Maximum . Minimum . Average {12) 0.436 0.031 0.192 1-7.'; 1.63 1.69 1. 07s 0.839 0-935 51-99 38-72 44.81 61.9s 36-03 48.5s Coal from the Lower Kittanning Seam of Pennsylvania, which occupies but a small space in Ohio, is coked at Leetonia, Columbiana Co., Ohio, for use in the blast furnaces located there. The coal s^am is about 30 inches thick, the upper 6 inches being non- coking, and used in the furnace in its raw state. A sample from the bottom bench of tho Salem shaft shows the following composition : — Water . Volatile matter Fixed carbon Ash . Total 3 00 31-50 62.3s 3- '5 Sulphur .... 1.40 „ left in coke . . 0.60 „ of coke .... 0.92 Specific gravity . . . 1.274 Analysis from Proiessor Edward Orton. This coke was made in ovens of the beehive pattern, 12 by 6 feet, occupying seventy-two hours in the coking. It is used in the furnaces of the Cherry Valley Iron Company at Leetonia, 75 feet by 16 feet and 55 feet by 14 feet. In the large furnace, it carries a burden of about 2 pounds to I pound of coke. This coke exhibits very plainly the effect of a high percentage (31.50 per cent.) of volatile matter in the coal, for while all the cokes previously described have had hard and comparatively thick pore walls, in this one the pore walls are very thin and papery, and crush very readily, so that its practical reputation is much lower than other fcokes, especially the Connellsville, with which it comes into close competition. It has the advantage, however, of being in close proximity to valuable iron ore deposits. A series of twelve specimens yielded the following results : — COKE. — LEETONIA, COLUMBIAUA CO., OHIO. Moisture. True Specific Gravity. Apparent Specific Gravity. Per Cent, of Cells by Volume. c.e. in 100 Grams. Maximum . Minimum . Average (12) 0.142 0.012 0.047 1-55 1.46 1-49 0.844 0.706 0.770 52-83 36.06 47-59 74.06 42.71 62.23 In the western portion of the country, the younger coals of the Cretaceous. 158 SPECIFIC GRAVITY ANDPOROSITY OF COKES. and Tertiary have been coked with success at various localities, adding very much to the value of mines of all kinds by greatly reducing the cost of fuel for the metallurgical works. Coal from the Laramie formation, which lies at the boundary between the Cretaceous and Tertiary, is coked at El Moro, Las Aminas Co., Colorado, for use at South Pueblo, Pueblo Co., Colorado. The composition of the coal is represented by the following analyses : — "Water at i io° 0. Volatile matter Fixeil carbon . Ash Sample across the Seam, leaving out the Stony Parts. . 0.95 . 29.82 56.41 12.82 Total Sulphur . Specific gravity 0.41 1-305 Analyst Sample from s Car-load. 1. 14 29.97 56.32 12.57 100.00 H. L. "Wells This coke is made in ovens of the beehive pattern, 1 1 feet 6 inches by 6 feet, the charge being 4.2 tons, the yield 60 to 65 per cent., and the time of coking forty-eight hours. The amount of ash, as shown by about forty analyses by Mr. "Wells, is 18 per cent., and the percentage of silica in the ash 12 per cent., the sulphur is from 0.46 to 0.53 per cent. The coke is used in the furnace of the Colorado Coal and Iron Company, at South Pueblo, Colorado, 65 feet by 15 feet, carrying a burden of 2 pounds to I pound of coke. A series of twelve specimens yielded the following results : — COKE. — EL MOBO, COLORADO. Moisture. True Specific Gravity. Apparent Specific Gravity. Per Cent, of Cells by Volume. c.c. in 100 Grams. Maximum . Minimum . Average (12) 0.225 0.025 O.I 14 1. 61 1.69 1.047 0.766 0.919 54.66 41-47 45-75 71-36 41.56 50.39 Coal from the Fox Hills group of the Cretaceous is coked at Crested Butte, Gunnison Co., Colorado, for sale in the open market. An average sample taken from the entire face of the seam, 7 feet thick, showed the following composition : — "Water at 110° C. Volatile matter Fixed carbon Ash . Total Sulphur Analyst, H. L. "Wells. 0.72 23-44 71.91 3-93 100.00 0.36 This coke is made in ovens of the beehive pattern, 1 1 feet 6 inches by 6 feet, the charge being about 3.75 tons, and the yield about 70 per cent. The time of coking is forty-eight hours. It is used principally by the lead smelters, in cupolas, &c., in Colorado and the adjoining country. COKING IN HEAPS. 159 The composition of the coke is as follows : — Water • '-55 0.41 Fixed tai-bon 92.03 92.44 Asb . 6.62 7-'S Sulphur . 0.58 0.55 The amount of ash, as shown by six analyses by Mr. Wells, is 8.7, the percentage of silica'in the ash being 4.6 per cent.; the sulphur is from 0.37 to 0.58 per cent. A series of twelve specimens yielded the following results : — COKE CRESTED BUTTE, COLORADO. Moisture. True Specific Gravity. Apparent J-peciflc Gravity. Per Cent, of Cells by Volume. c.c. in 100 Gi-ams. Maximum Minimum . Average (12) 0.171 O.OII 0.073 1.62 '•53 '•59 0.968 0.848 0.907 47.01 37-39 42.96 55-4S 38-63 47-59 A series of twelve specimens from the Washington C!ity Gas Light Company, Washington, D.C., is added for the sake of comparison. This coke is such as is sold by the company for domestic u.se, and has been crushed and washed. Consequently, it shows in some cases a high percent- age of water ; it also shows, as might be expected from the method of its manufacture, wide variations in all the determinations. COKE. — WASHINGTON GAS WORKS. 1 Moisture. True Specific Gravity. Apparent Specific Gravity. Per Cent, of Cells by Volume. e.c. in 100 Grams. '33-49 51 »4 75-48 1 Maximum . Minimum Average (12) ^.529 0.179 0.802 2.07 1.48 1-74 911 0.497 0.772 66.39 4659 55-66 The above results have been put on record without drawing any im- portant conclusions therefrom ; although they are very interesting and in- structive, yet the investigation is only just fairly commenced, and inferences made at the present stage of the work may be materially changed by sub- sequent examinations. There is, perhaps, no subject on which more erroneous conclusions have been drawn from entirely insufficient and often imperfect data than that of coke, and it is especially to be desired that anything of the kind may be avoided in this investigation, which should be sufficiently extended to embrace a thorough investigation of the nature and composition of coking coals and their behaviour under varying conditions, as well as a large number of determinations of all the important characteristics of coke, so that it may furnish a basis for forming trustworthy conclusions in regard to the manufacture, the uses, and value of that material. For the sake of con- venience, a table is added (p. 160), showing all the important information at present accessible in regard to the cokes examined.* Coking in Heaps or Bidges. — The oldest and still in some parts a common method of preparing coke is in meiler or heaps, in which, however, the operation is not conducted in the same manner as in the wood meiler. No covering is employed, but carbonization is allowed to commence with * For additional particulars of m-inufacture of cofce in the United States, see Trans. American Inst. M. Eng. v also J. D. Weeks, "The Mineral Resources of the United States" (Washington); and -'Iron Age," vol. xxxvii. i6o SPECIFIC GRAVITY AND POEOSITY OF COKES. a « 05 1 •mqdins •qsv •aoqiBj) •MJBm II •2s g^^ :-i I ri I I ''"° 1 i>M n M n H Ao I 00 *ri I q iH w? q» « '■on ' tn ^ t^ fi . S td »4 t< ». g' « lili.liii ^^ b hi b h ^ gi jM a> « « w S! g j-g t » ^ » O.S 3^3 o o o o a " « s s 05 ■ = M gl 'spunoj •^00^ oiqnO '8[nsjf)ooi at *o'o i 8[[90 JO eoinioA "^ In r-' E-i tfJ -^ ^ X 3 "^ 1^ W &I n j>> '^ 0> M H 00 c*»0 00 on 'atunjoA iq aipo JO 'l^USO J3J • 19 -dg !)U3i'Bddv •JO -dg anax 'ajn^sioj/Q^ ^ uaquin^ N (C ^ ^ cT) f*ia) o »o Oi e* O M 00 O«00 S^ <^ X*«00 00 0> ON 9i ;> r« 6066606660000 -trr) — O iHO '♦OO M ■* t^ r- r* o q q q o q q q i-< -« o q 00 6 6 6 6 6 6''6 666066 PC"- . . .0 I CD CrcQ en b. 5 -^ gS|g| I? el's I n »»»*W)yO *^M ©vo k ■9!100 •qi I 0% aepjng epunoj I I -I »:■ I I ". \D i-- •*'0 m 'anviun^ X 1 1 1 XX 1 1 X XX 1 X 1 JO 9ZJS -§'.8 — T— . . . i 1 s Pm -^ *a*3 1 .43 -li^-^ 13 ss 1 33 1 S3 ' 2^ 1 § 1iJ-2 3 sJSi s d c a W i5 ss h5 A^'iAQ *SUI3f03 JO aui|x 'O'O ? a 00 00 I I II \ S II S"<5 88 •i 53 XX 2i X « » ® ai -a s *mioqd -soqa BO CO ^1 no S •qev •uoqjBO pexij •JOJIBK 9IHB10A •J9*«M 'jaqoicif^ O 'O O O 6 o « q I 00 ti rTi IT) 1 1 1 1 I I OJO 6 6 o o q *7 00 00 I I 1 1 "So •"» .SP ^5 « a o o EH 1 w wi ^->n^O x^« 0> O >-■ < COKING IN HEAPS. l6l free access of air, a coating of dust being first apjUed when the coke has already been produced, and the attention of the burner is required to prevent its further consumption. The foundation for the meiler being stationary, it becomes suiiiciently covered of itself with coke debris. In order to pre- pare larger quantities of coke at once, long ridges are often substituted for the original round meiler, the length of which varies with circumstaiices and the consumption of coke ; they may sometimes extend to the length of 2 oo feet. On erecting one of these ridges, a string is stretched along the coking station, in the direction of which large pieces of coal are placed slanting against each other, leaving a triangular space between them, so that a longitudinal channel (ignition passage) is formed, through which the string passes. In arranging the pieces, it is necessary to pay attention to the natural strati- fication of the coals, which should be at right angles to the longitudinal direction of the ridge. Parallel with the first series of coal, is placed a second, and then a third, and so on ; but the pieces constantly diminish in size, until the station measures 6 feet on both sides. Upon this sub- structure the heap is then made, without particular care in the arrangement, the largest pieces below and the smallest above, until it has reached a height of about 2 feet. To facilitate the ignition, stakes are rammed in at distances of 2 feet from each other, projecting above throughout the whole length of the ridge, which, when subsequently removed, leave vacant spaces for the introduction of burning coal. The ridge, being thus kindled at more than a hundred distinct spots, soon breaks out into active combustion. As soon as the burner observes the thick smoke and flame cease at any one part, and a coating of ash making its appearance, he endeavours to stop the progress of the fire by covering it with powdered coal- dust, repeating the operation until the whole ridge is covered, when it is left two or three days to cool. The covering on the side exposed to the wind should be the thicker, and increased in stormy weather. When the fire is nearly extinguished, which occurs in two or three d^s, the coke is drawn. This mode of coking is simple, but not very economical. The fire, proceeding from the upper part of the ridge in a downward direction towards the lower and interior parts, converts the coal in the upper strata into coke before that in the interior has acquired the temperature necessary for charring, and is still in want of BP3(iS I I 1 I I 00 00 "O a. 00 00 I I 'SSdUpjGH fO CO ro rn f*^ ■aacdg jqnnao jo op^H )noq}iM pa'jioddns ao?iunj as !N 00 00 '(asa^sisag aiugjjxjy oqi jo \) qaii{ aiqnQ jod ?= = -" m 1^ vS- fO 1^ in « 10 ? «} 00 10 CO ■^ ^ CO CO 00 CO CO CO 9 N 1^ 0^ 00 10 IN 00 i5 \o ■^ ^ 00 00 10 S' >o VO LO ■s in 00 00 S ^ S" CO 10 00 ■* H 00 00 ON -o- 4 ON O* 00 VO CO 0\ Os VO \o VO r->. K vO CO ^ VO CO 8 s s, M CO :: -j- N CO HH CO M ^ r^ c: Ml o 3 ^ a " bo H O O O in Fig. 106. GASES FROM COKE OVENS. 20 1 The ovens are cylindrical, with a door at each end. There are three chimneys ; one in the centre of the range, and another at each end. The dimensions of the central one are equal to those of the other two, but the three are not employed at the same time. It is found that the dimensions of these chimneys are of great importance, as they regulate the admission of air into the ovens, and the rapidity of the process of coking. Eight ovens discharge their products of combustion into the central chimnej', and the hot gases passing under a steam boiler raise sufficient steam for an engine of 80-horse power which drives the blast furnaces of the iron-works. The coal employed at these works belongs to the caking class, and yields by direct analysis ; „ , (Carbon 78 Volatile matter 2 20 100 The composition of the coal approaches that of Kochebelle, which consists, according to Kegnault, of : Carbon .... 89.27 Hydrogen .... 4.85 Nitrogen and oxygen . . 4.47 Ash . . . .1.41 100.00 The coking lasts about twenty-four hours, and the yield of coke in the 'ovens averages 67 per cent. M. Ebelmen collected the gas at three different periods, and analysed it with the following results : — After 3 Hours. After ji Hours. After 14 Hours. Mean. Carbonic acid . Carburetted hydrogen Hydrogen Carbonic oxide . Nitrogen .... Oxygen to lOO vols, of nitrogen 10.13 1-44 6.28 4.17 77-98 9.60 1.66 3-67 3-91 81.16 13.06 0.40 1.10 2.19 83-25 10.93 1.17 3.68 80.80 100.00 iS-7 100.00 14.2 100.00 17.0 100.00 IS.6 The relation, then, between the coal and escaping gas is as follows : — Coal. Coke left. Oas. 89.27 ... 67.00 ... 23.68 4.8s ... - ... 4-85 4-47 -■• — - 4 47 I.41 ... — ... — Carbon Hydrogen Oxygen and nitrogen Ash . 33-00 100.00 = 67.00 The relation of the carbon to the hydrogen is as 23.68 : 4.85, or i to 0.205 by weight ; while the relation in the gas, according to the mean of the above analyses, is i to .064 by weight ; from which we may infer that I of the hydrogen of the coal is consumed during the carbonization. There is only a very small qiiantity of tar produced in consequence of the high temperature of the ovens ; this also accounts for the small quantity of carburetted hydrogen found among the permanent gases. The mean quantity of oxygen, 15.63 for 100 of nitrogen, shows that 10.63 must have combined with hydrogen and passed off as aqueous vapour, as 26.26 parts must have been introduced for every 100 of nitrogen; but 202 TAB FROM COKE OVENS. much stress cannot be laid on this inference, as the amount of air admitted to the ovens is not stated. These data further prove, that | of the whole heat which is lost is sensible, and of course necessitates that it should be rendered available on the spot, as it cannot be conveyed to any great distance, more especially as the gases do not contain much combustible matter. It is evident that the heat necessary for coking is produced partly by the combustion of the pro- ducts of distillation, and partly by the burning of a portion of the residual coke. The cost of making coke in this country used to be about is. 2d. per ton; but it is now increased slightly above that figure in consequence of higher rates of wages. Ohuvging and burning coke, with all attendance required, including filling waggons • o Fillingovens with coal . • o Wear and tear of ovens . • • o Total cost . I d. 10 {)er tod coke 2 „ „ 2 „ „ Mr. Dixon, of Crook, however, gives the cost of labour at ordinary bee- hive ovens at is. o.e^d. per ton of coke. Wear and tear of ovens is not in- cluded in this. TAR FROM COKE OVENS. The preparation of coke is necessarily a process of destructive distillation, and consequently involves the formation of tar. Increased economy in the manufacture of coke has led to methods which include, the collection of the tar (pp. 180-192.). The general properties of a coke-oven tar must obviously depend on the temperature, when the coal distilled is the same. It is in fact found that such a tar as that from the Jameson coke ovens, where the heat at the point of destructive distillation is extremely low, is very rich in paraffins and kreasote phenolds — phenol and the aromatic series in general and non- volatile products being absent in quantity. Tar from the Simon-Carves ovens, on the other hand, is the result of a very high temperature, and chiefly remarkable for the enormous amounts it contains of naphthalene, anthracene, and non-volatile products — the paraffin series being almost entirely absent. The tar from blast furnaces is of intermediate quality. It is chiefly to "Watson Smith* that we are indebted for the analytical examination of these tars. The following is a summary of his results. Jameson Tar. — The average specific gravity is 0.97. Naphthalene and anthracene, though carefully tested for, could not be found. The oil was not fluorescent. The following is an example of the fractionations : — Fraction. Temperature. Specific Gravity. Volume. A. Below 150°' .829 0.8 B. iSo°-230° .892 V C. 23o°-30o'' •953 36.0 D. 3oo°-35o° .970 6.7 E. 3So°-400° .971 19.0 F. Above 400° oil solid on cooling 9.8s 0. Paraffin soft scale — 545 H. Pitch — 10.00 Loss 2.00 100.00 ■ " Jour. Soc. Chem. Ind.," 1883, p. 495 ; " Jour. Iron and Steel Inst." 1884, No. 2 pp. 486-516. BLAST-FURNACE TAR AND COKE-OVEN TAB. 203 A little toluene and xylene were found in fraction A ; B perhaps con- tained a small quantity of phenols, which were accompanied by a burning oil of bad quality; C was a light yellow oil, not very suitable for burning; D had too little body for a lubricant ; B was a fairly good lubricant ; F and G yielded a satisfactory amount of scale. The pitch gave off ammonia. Closer examination of the " phenols " of this tar showed the presence of much sulphuretted hydrogen, the oil itself consisting chiefly of kreasote phenoids, and not of phenols. It is noteworthy that, in the treatment of these tars, Smith did not employ steam in the distillations. Blast-furnace Tar. — The samples were obtained from Gartsherrie (Scot- land), where a process is in operation for recovering ammonia as well as tar from blast-furnace gases. The volume of the gases is about 120,000 cubic feet per ton of coal. The tar may be regarded as in fact a coke tar. The specific gravity of the tar was .954. One of the heavier fractions showed green fluorescence. The following results were obtained on distilla- tion ; — Temperature. Specifie Gravity. Percentage Volume. Below 230° 23o°-3oo° 300° until solid Soft scale f Water 1.007 toil .899 .971 ■994 .987. 30.60 2.91 6.97 13.02 16.75 Coke, 21.4 per cent. ; loss, 5.5 per cent. Anthracene was absent. None of the oils were found very suitable -for lubricating purposes or for burning in lamps. The phenolic portion, dissolved out by soda, contained a little ordinary phenol, rather more creasol, and abundance of phenoids ; coke, about 5^ per cent. Simon-Carves Tar. — Specific gravity 1.106. In general appearance this tar closely resembles that from gas retorts. Naphthas, benzene, and car- bolic acid are present in small quantity only, the characteristic feature of the tar being its large percentage of naphthalene and anthracene. Watson Smith gives the following results : — Temperature. Percentage Volume. Remarks. Below 100° 6.2 Water. „ 120° 1.6 — „ 210° 2.9 — „ 220° „ 230° „ 3°o° Above 300° 1:3 0.1; 18,6 34-2 Chiefly naphthalene. Naphthalene, anthracene. Crude anthracene. . Half -coked pitch, about 33 per cent. ; loss, about i per cent. Most of the " gas-producers " yield small quantities of tar, the nature of which lies well within the range above described. Distillation of Peat. — A patent was obtained in the year 1849 by Mr. Rees Eeece for the production of gas, paraffin, oils, pyroligneous acid, pyroxyKc spirit, and ammonia, from peat, by which the bog lands of Ireland, hitherto a reproach, were to be converted into a mine of wealth to the country.* The process, as patented by Mr. Reece, consists in burning peat in a blast fur- nace of similar construction to the iron blast furnaces, only closed at the top and furnished with apparatus for carrjing away and condensing the volatile * On account of its great historical interest, a somewhat minute description of this process has been retained in this edition of the work. 204 DISTILLATION OF PEAT. products of distillation. Fig. 1 1 1 shows a sectional elevation of the blast furnace, and Fig. 112 a plan of the pair of furnaces intended to work together with the pipes for condensing the products. Fin. III. The drawings are taken from Mr. E.eece's original specification. The fur- naces and condensing apparatus, subsequently erected on the Bog of Allen, Fm. 112. near Athy, were somewhat diflferently constructed ; the furnaces had more the shape of iron blast furnaces, were built of brick, 10 feet in diameter at the widest part, and encased in sheet iron, the mouths being furnished with a double cone, similar to that shown in Fig. 136, page 229. The condensers were not surrounded by water, but were upright, connected together two and two at the top, and terminating at the lower open extremities in a metal box, with a diaphragm, which served Fio. 113. as a recipient for the semi-solid tar, and, at the same time, as a valve for preventing the escape of the gases. It was calculated that 12,000 feet of surface would be required to condense the products from 100 tons of peat. Scrubbers were erected at the end of the very extensive series of condens- ing pipes, in which the escaping gases were well washed with water, and the last trace of ammonia removed. The furnaces being charged with air- dried peat, ignited at the bottom, and closed, the blast was applied, furnishing 3000 cubic •feet of air per minute, the amount required for the distillar tion of 100 tons of peat in the twenty-four hours. The heat from the combustion of the peat in the lower part of the furnace was thus employed to distil the upper layers ; the products DISTILLATION OF PKAT. 205 of combustion, with the proceeds of the distillation, being forced forward by the blast to the condensers. The crude products of the distillation were tar, water, and gas, the ashes of the peat fluxing, according to Mr. Reece, and flowing out as slag. The two former, the tar and water, were collected in tanks connected with the con- densers, while the gas passed on through flues to the various boilers, evapo- rating pans, tar-stills, &c., where it was employed as fuel. From 100 tons of peat, 6 million cubic feet of mixed gases were said to be obtained, consisting of hydrocarbons, free hydrogen, and carbonic oxide, some nitrogen and car- bonic acid ; it was calculated that 2 millions of cubic feet would be sufficient for carrjdng on all the operations connected with the manufacture of the products, leaving 4 millions to be applied to other purposes, such as burning lime, making bricks or glass, for which the gas, on account of the absence of sulphur, was said to be peculiarly well adapted. The water, which could be easily separated from the tar which swims on its surface, amounted to from 10,000 to 12,000 gallons from 100 tons of peat. The water contained wood naphtha, or pyroxylic spirit, with acetate and carbonate of ammonia in solution. Lime was added to it in the propor- tion of 6 cwt. to 10,000 gallons, and the ammonia and naphtha in the rough liquor, were separated by a modification of Coffee's still. The mixed vapours of ammonia and naphtha, being separated from the dilute solution of ace- tate of lime, were passed through a closed vessel containing dilute sulphuric acid, which converted the ammonia into sulphate, whilst the naphtha was again passed through a similar apparatus, or " rectified at once by blowing steam into it in a close safe, with a set of cups attached." The acetate of lime, or " spent-vash," from the distilling apparatus, was boiled down in large evaporating pans of cast-iron, or boiler-plate, until the solution con- tained about 10 per cent, of acetic acid. The crude acetate was then de- composed by sulphuric acid, and again distilled, the free acid recombined with lime, and boiled down in leaden pans to the point of crystallization. The tar from 100 tons of peat was said to contain from 300 to 350 lbs. of paraffin, a mixture of hydrocarbons first discovered by Eeichenbach in the tar of wood. This was the most valuable product from the distillation, and in . order to separate it from the oils in the tar which accompanied it, the latter was melted, and while at a temperature of 38° C. (100° F.), 20 gallons of sul- phuric acid were added, and well agitated for about twenty minutes. Much of the tar was thus charred, and rendered heavier than water, and this portion, with the basic oils, sank on the addition of hot water, while the paraffin and lighter oils came to the surface. These were distilled either by direct furnace heat or by superheated steam, and. the more volatile portions, about one-half of the whole, collected apart from the heavier oils and paraffin. This latter portion was allowed to cool, when the paraffin crystallised in flakes which floated in a liquid oil ; this was strained, and the crystalline mass pressed to remove the oil. The paraffin was subsequently purified by a repetition of the same treatment, and was then in a fit state for the market. The oils which accompany the paraffin had, unfortunately, a Very foetid odour, which rendered thern useless in their crude condition ; they had, therefore, to be treated with caustic soda, or lime, and subsequently with oil of vitriol, before they could be applied to lubricating or other purposes. Messrs. Kane and Sullivan submitted the whole of the products resulting from the distillation of different varieties of peat, both in close vessels and by means of a blast of air, to a strict examination on a small scale, with a view to test, in the laboratory, as far as possible, the probable economic value of the process. The chemical nature of the specimens employed in this in- vestigation will be found on pp. 15-20, under the head of " Peat or Turf." Their results, as far as the nature of the products and the quantities in which 206 DISTILLATION OF PEAT. they are obtained are concerned, corroborate generally those of Eeece ; but they were unable to separate and purify these products by the methods he employed ; nor could they obtain combustible gas at all in conducting the distillation with a blast of air, although the quantity of air admitted was varied in different experiments. It was also found very diflScult to condense the products in the latt^ case, and to regulate the blast so as to obtain the products in any quantity; if too little force of blast was employed, a very long time was required to consume the peat, and a large produce of tar, some light carburetted hydrogen, but chiefly carbonic acid gases, were obtained ; if too much air was forced through the furnace, hardly any" tar or liquid products were condensed, while a considerable amount of carbonic oxide was produced. It was inferred from these facts, that, if it were necessary to produce carbonic oxide for the manufacture, no tar would be obtained ; whilst if the operation were conducted sufficiently slowly to form tar, it would be found impossible to obtain carbonic oxide. In every case of imperfect combustion, the aqueous liquid was acid at the end of the operation ; whilst in closed cylinders, and when the blast was properly regulated, the alkaline reaction increased with the temperature and rapidity of the distillation. In no case was the tempera- ture in the apparatus very high, and always quite inadequate to flux a sub- stance composed of the ingredients contained in ordinary peat ashes, although Mr. Reece obtained a fused slag as the residue in his process. "With a proper regulation of the blast, it was found that the condensable products increased with the length of time occupied in working off the charge, and laarge quan- tities of ulmin-like resinous bodies were obtained, which it was apprehended would be liable to clog the condensing apparatus. On the whole, however, with a careful regulation of the blast, very nearly the same results were ob- tained with this apparatus as in the close vessels, as will be seen by the fol- lowing Tables, in which the results are given, and compared with those obtained by Mr. Reece. The elementary composition of the specimens ex- perimented upon will be found at pages 15 and 20. Table I. — Representing the Percentage of Tar, Water, Charcoal, and Gas, obtained from the Specimens 0/ Feat subjected to Distillation. Number of Specimen. to Locality from whence Obtained. Water. Tai. Charcoal. Gas. I 2 3 4 5 6 7 2 and 3 7 9 Ditto 22. 24 Mount Lucas Bog, Phillips- town .... Light Surface Peat from the Wood of Allen . Black Compact Peat, Wood of Allen .... Tichnevin .... Ditto, distilled with retort heated to redness Upper Shannon . Upper Shannon . 23.600- 32.273 38.102 33-628 32.098 38.127 21.819 2.000 3-577 2.767 2.916 =-344 4.417 1.462 37-500 39.132 32.642 31. no 23-437 21.763 18973 36.900 25.018 26.489 3=-340 42.121 35-693 57-746 219.647 19.483 204.557 256.313 31.378 2.787 29.222 36.616 PEODUCTS OBTAINED FROM PEAT. 207 8 an ss <> «^ 5!5 Ci -S 1 •S' ^ •S r '^ Rh ^ s- ■< ^■. i. ^ V ^ ■» W b ^ £ Oh I, n •^n« jad 96? o— -sqi t-Zgg = St 'uoi[b9 ain O'i 'sqi 6 pi 'qoiqAi 'I'lo JO siio[ib3 9'g6 iqaiiC juad JO Buoj 001 '8D88a o| SuipaoDoy ON 5 iri r^ ro 00 in 000 (T) o 1 ■JU30 .isd £o80= •sqioogi = 'no[]wS aqi 01 -sqi 6 ;« 'qoiqii '[[ojosucubSooj }BoqB piaii^ead JO suo} 001 'aoaag oj Suipaoooy s" 1- M \0 in N 00 00 ^o ^ 0-0 « ■juao jad qSi'o 0) E£ro= -sq; oS£ o; oo£ piajiC quad jo eno) 001 — : iiaaajj '^ 0^ ui o ^ O ^ o - '-' era oraiq JO aj'B^sov Jo X^i^ubo^ •dxnvj JO a^-B^anv p .iH^aBiij) Snipuodssiioo •(OH + ^O^H^O) •pioy 01^80 V 'jo 9;Biid|ns JO Xji^nBD^ JO ajBqding JO Xiipocn^) Saipnodsajjoo ej ppp^ [jBsd JO suo:^ ooi : aoaag JO '^jitto "t'l ppiiC (^Bad JO suo^ ooi MM -00 d d d 1 y3 vo 00 00 0^ M >-< M 6 d ■inaoaadooi= 'umoraniB jo ajBqd -jns JO uo( I piatf ?Bad jo suoj 001 1000 t>. 10 1^ d d d o 00 S 9 vo"? ^. a g si ^^ ■ =^= I «> ^ S ■;<» So -a OS t^ 13 t) ^ a k;3 ^ hpS cb I 2o8 ARTIFICIAL OE PATENT FUEL. Table III. — Representing the Proportions of Water, Tar, Ash, and Gas, obtained by the Distillation of Feat in a Blast of Air, with the Corresponding Results obtained with a Closed Retort. I 2 3 II Locality of Specimen. Waibe. Tab. Ash. — sr Gab. ' In Blast of Air. In Closed Retort. In Blast of Air. In Closed Retort. In BU»t of Air. • In Closed Retort. In '■' Blast of. Air. t 7 9 24 Light Surface Peat —■Wood of Alien . Dense Peat— Wood of Allen . . . . Shannon — No. 4 31.678 30.663 29.818 32.273 38. 102 21.819 2 510 2-395 2.270 3-577 2.767 1.462 2.493 7.226 2.871 2.745 7.898 2.976 63-319 59-716 65.041 Table IV. — Representing the Percentage of Ammonia, Acetic Add, Pyroxylie Spirit, Paraffin, a/nd OUs obtained by the Distillation of Peat in a Blast of Air, and the Corresponding Results obtained with a Closed Retort. £ a . Locality of Specimen. Ammonia. Acetic Acid. Pyroxylie Spirit. Paraffin. Oils. a.- (5^ |\ 5^ li SK li fl. z 2 3 7 9 24 Light Surface Feat- Wood of Allen. Dense Peat— Wood of Allen Shannon— No. 4. 0.322 0-344 O.I94 0.187 0-393 0.181 0.179 0.268 0.174 0.206 0.286 0.161 0.158 o;is6 0.106 0.171 0.197 o.ti9 0.169 0.086 0.119 0.179 0.075 0.112 1.220 0,946 I.OI2 14s; 1.36 o.t|i3 J- 530 1.177 3) 860 761 621 6S3 420 487 374 366 3.178 Aver ige 287 254 207 21B 140 162 125 122 1.059 Rcece. 84-45 ... 85.22 •4-83 14.78 .72 — The amount of paraffin, according to these experiments, obtained from I ton of peat does not exceed 2| lbs. An analysis of it is subjoined :— Carbon Hydrogen . Oxygen, or loss . 100.00 ... 100.00 indicating a close approximation to that of the paraffin from beech-wood tar. AKTIPICIAL OB PATENT FUEL. It is obvious that the invention of any new or artificial fuel, is in itself an impossibility, unless the term is used to imply an adaptation of those natural fuels which have been rendered unfit for use by too great subdivision. It is in this sense that the term is here employed; In some parts of Norway, where large quantities of saw-dust accumulate at the mills, 18 to 24 parts by bulk have been mixed with 8 parts of clay and J of tar, and formed into bricks for boiler fires. Attempts have been made to employ small-wood refuse, shavings, saw- dust, tan, charcoal- and coal-dust, and similar substances for the production of gaseous fuel, in the manner which will be described below, but they do not appear to have been attended with invariable success. The substances AKTIFICIAL FUEL. 209 chiefly employed in the manufacture of artificial fuel are charcoal-dust, peat or turf, small-coal, slack or brees, with refuse fat, tar and pitch. Refuse charcoal, peat, and other vegetable substances, have been charred with tar and pitch, and submitted to pressure, as described at pages 1 1 2—1 14. Charcoal-dust is also stated to have been economized in French iron- furnaces by allowing the blast to carry a certain portion of it into the body of the furnace. A patent was taken out many years ago, in the Austrian States, by Swozil, for converting turf into a hard substance, resembling coal, by mixing certain organic liquids with it, which gave rise to a species of putrefactive fermen- tation, after which it burned with remarkable ease and considerable heating power. Mr. Hill distils dry peat, and collects the pyroligneous spirit and tar. The tar is converted into pitch, which he mixes, while hot, with peat char- coal, and thus renders a very bulky, and, for many purposes, valueless article, one of considerable importance. "WeschniakofF many years ago manufactured from a mixture of small coal and refuse animal fat a substance which he called " carboleine." In this process, an excess of fat and small coal were well mixed together and made into the form of bricks, and the mixture submitted to pressure between coarse haii'-cloths. This substance, as analysed by Kaiser, was composed of : Small coal Fat Ash 84 8 The specimen analysed by Kaiser on Berthier's plan was found to be inferior in heating-power to good English coal, owing probably to the inferiority of the coal employed in its production. Being in the form of bricks, however, it had the advantage of occupying but a small space when packed in steam-vessels. Wylam's Patent Fuel. — Another process, of a much more extensive and important nature, has been carried out on a large scale by Mr. Wylam. The substances employed in the manufacture are small coal and pitch, which are moulded together by pressure into bricks. As this manufacture consists, how- FiG. 114. ever of several distinct branches, it will be better to consider them separately. The first operation is the separation of coal-tar by distillation into naphtha, dead oil and pitch. The pitch is subsequently mixed with small coals, and p 2IO AETIFICXAL FUEL, WYLAM'S PROCESS. then moulded. The naphtha is rectified and sold as such, while the dead oil is converted into ivory-black or employed for preserving timber. The tar is steamed to facilitate the separation of the naphtha. The process of distilla- tion is conducted by exposing the tar and water to the heat of acommon fire in a large iron retort, A, Fig. 114. Two pipes, B and G, uniting at H, convey the volatile products from the retort. During the first stage of the distillation, the pipe C is closed by a valve at d, and the naphtha and water escape through the swan-neck shaped pipe B, which is carried a,bout 3 feet above the retort, to prevent any dead oil passing off" at the same time, during any sudden ebullition of the contents of the retort. The pipe then passes through a condenser F, kept cool by a stream of water, and discharges the naphtha and water into the vessel G. The naphtha floats on the top, and flows off in a continuous stream at g, while the water syphons itself off by the syphon iT, Fig. 1 1 5, as it accumulates. As soon as all the naphtha has Fia. 115. Fia. 116. passed over, the pipe c is opened, and more heat applied, until the distillation of the dead oil is complete. The pitch which remains behind is ultimately drawn out by an opening at the lower end of the retort, into shallow stone coolers. / indicates the position of the fire-places, and X K the flues for heating the retort. Fig. 116 shows an end view of the swan-neck of the retort. . The naphtlm is redistilled by steam, and the dead oil obtained as the second product of the distillation of the coal-tar, is sold for anthracene extraction, and for preserving timber from decay when exposed to damp and water, as in railway sleepers, piers and docks. It is also employed, after the said extraction, as a solvent for pitch, in which case it makes a valuable varnish, for coating wood and iron-work exposed to IJ the weather, and lastly, for the manufacture of a very superior lamp-black. The arrangements for making the lamp-black are very simple. The dead oil, which is kept in a large reservoir, is heated by means of steam, to render it more fluid, so that it may flow through the pipe A, Fig. 117, more easily, and ultimately arrive at D. It is ignited at this point, and the lamp-black which is produced is deposited in long galleries, into which it passes through the flue C. The large chamber B is constructed with, the view of preventing occasional explosions extending into the galleries. Fig. 118 shows the end-view of the burners £ E. WYLAM'S PATENT FUEL. 211 The pitch after having become hard, is ground under edge-stones, and mixed with small coal in the proportion of i to 4. The mixture of coal and pitch is carried up into a large hopper, from which it gradually passes into Eia. 117. the receiveTS M M M, Kg. 119. At the bottom of these receivers, a pair of plain rollers 0, Fig. 120, are kept in motion by the shaft Jf, Fig. 119, and by Fio. Fia. 118. 119. this simple contrivance, a regular supply is thrown into the retort R. An. Archimedean screw Q, Fig. 120, is also made to revolve inside the retort, by the shaft iV. The retort is maintained at a dull red heat by the hot air ia the flue T, and the fuel passes through the whole length of the Fm. 120. retort, which is some 15 feet long, in about three minutes. The mass of coal and pitch is discharged at the opposite end of the retort in a pasty state, and carried by an endless chain into the receiver S, Fig. 121, where it is kept in motion by the arms r r, so as to prevent it liardening into 'lumps. From this cylinder or receiver it runs into large moulds, where it is subjected to a heavy pressure in the following manner. A represents a moveable oval table, upon which the moulds £ B are fixed, S the vessel which receives the fuel paste, u and x two cylinders similar to those of a steam- engine, but worked by water, v y the pistons, to which two rams are attached, each having six arms that fit accurately the moulds B B, and « is a lever, worked P 2 Fia. 121. 212 ANALtSES OP PATENT FUELS. by means of the motion of the piston y, the moulds are filled from the vessel S, as the table is made to revolve by the -movement of the lever z. As the moulds approach the cylinder u, the piston descends and compresses the fuel with an enormous pressure ; after the piston rises, another set of moulds take their places, while the piston y of the cylinder k having de- scended at the other end of the table, the six bricks are forced out of the moulds, and are received below ready to be stamped with the maker's name. The machinery and the whole arrangements are exceedingly beautiful, and the accompanying sketch is only intended to convey an idea how the process is effected, without showing all the details of the mechanism. The analysis of this fuel gave the following results : Carbon . Hydrogen Nitrogen . Oxygen . Ash 76.60 S-I5 I.S4 963 7.08 100.00 Colcefi-''™ \ olatiie matter 61.67 7.08 31-25 The following table shows the composition of several specimens of artificial fuel, as ascertained by the officers of the Admiralty investigation. Locality or Name of Coal. Specific Gravity of Fuel. Carbon. Hydro- gen. Nitro- gen. Sulphur, Oxygen . Ash. Percentage of Coke left ; by each Fuel. ' Warlicli' 8 patent fuel . Livingstone's steam fuel Lyon's patent fuel Wylam's ,, „ Bell's Holland and Green's 1. 15 1. 184 I-I3 1. 10 1. 14 1.302 90.02 86.07 86.36 87.88 70.14 5.56 4.13 \% 5.22 4.6s trace 1.80 1.06 1.68 0.81 1.62 1. 45 1.29 1.25 0.71 included in ash 2.03 2.07 6.63 0.42 2.91 4.52 4.66 :s 13-73 85.1 65.8 71.7 The pitch employed in the manufacture of the patent fuel had a sp. gr. of 1. 01016, and yielded the following analytical results: Carbrn Hydrogen Oxygen Ash . 73-56 8.08 17.79 -57 It contained no hygrometric moisture, and Wylam's patent fuel con- tained only 0.86 per cent. A glance at the above composition of the pitch proves how valuable the substance must be in the manufacture of a fuel destined for raising steam on board steam-vessels. The large proportion of hydrogen and oxygen, add materially to the amount ofi flame it will produce, and the facility of its combustion. And it is obvious, that a fuel manufactured from this sub- stance in proper proportion, with a suitable small coal, must far surpass any natural coal for steam purposes. Some years ago the pitch produced from the distillation of gas-tar accumulated to such an extent, notwithstanding its application to patent fuel, as to be a very serious burden to many of the naphtha manufacturers, and in order to get rid of it they adopted a plan of converting it into coke and obtaining an additional quantity of pitch- or dead-oil. This process, now obsolete, was carried on in fire-brick ovens from 4 to 6 feet square by about 3 feet high, arched over at the top, from whence a 'large iron pipe carried off the very heavy vapours, which were easily condensed. The ovens bad two doors opposite each other on either side ; they were heated from WAIILICH'S PATENT FUEL. 213 below, and when red hot a charge of pitch was introduced and distilled for several hours, the doors being closed. When the charge was worked off, the doors were opened, the pitch-coke removed, and air allowed to enter the kilns for some time, in order to burn off the thick coating of coke which had been deposited upon the sides and arch of the ovens from the decomposition of the tar vapours. The heat thus generated kept the walls at a red heat, and but little additional fuel was required to work off the following charge. The pitch-coke thus obtained was very dense and hard, and much prized by iron- founders and others on account of its small quantity of ash and its freedom from sulphur. Petroleum -still coke is the modern representative of this coke. Warlich's Patent Fuel. — Warlich's object is to render patent fuel more capable of sustaining the heat to which it is subjected on board steam- boats, particularly in hot climates. He employs the bricks made of the usual materials, but adds a little common salt or alum, to prevent the evolution of too much smoke, and subjects them in retorts to a temperature of 400° F. and upwards, for six to eight hours, while he assists the evolution of the gaseous matters by an exhausting apparatus. It should, however, be stated that the presence of sulphates, such as alum, tends to retard combustion, and is otherwise injurious because it involves the formation of sulphides, which attack ironwork. Fig. 122 shows an elevation of a retort and furnace, and Fig. 123 apian. Fig. 122. Fio. 123. Fig. 124 is a transverse section of one of the retorts and furnaces. Fig. 125 is the longitudinal section of the retort; a is the chamber in Fig. 124. Fio. which the fuel is placed, and which is fitted with sliding doors ; c c are the rails for the carriages, which have several shelves, on which the manu- factured fuel is placed ; e, eduction ways for the gases expelled from the 214 PATENT FUEL MANUFACTURE AT BLANZY. Fio. 126. manufactured fuel, which by means of a dip-pipe / convey the products into the main g, as is practised in the manufacture of coal-gas. Eig. 126 shows a section of the exhausting apparatus, which consists of two cylinders h h, open at bottom, working in vessels ii containing water. The motion com- municated to the beam j by the connecting-rod k, alternately raises and lowers these cylinders ; g is the main, with two branch-pipes 1 1 and valves mm opening upwards; nn are two dip-pipes into the tank of water 0. The products pafes from the chamber retort into the main g, thence into the vessels h, whence they are forced below the water in the tank 0. The fuel is heated in the chamber by a current of hot air, which passes into the retort through the openings jB/). The apparatus is similar to that suggested by J. D. Stagg and employed at Bagillt for condens- ing lead-fume. Briquettes. — The following method is adopted at Blanzy for working up the small coal which accumulates in large quantities at the mines. The coal, which is first washed in the ordinary way and dried, is mixed with 7 or 8 per cent, of tar in the cold, and made into bricks by means of the following machinery. In Figs. 127 and 129, ^ represents the ash-pit of a Fin. 127. furnace, B' the metal plate between the door C and the grates B, D an arch to depress the flame so that it shall pass under E and spread itself over an extensive surface in F, where it heats a metal cistern turning on a pivot /. The smoke passes oif by a chimney G ; the metal cistern m m is driven by a pinion r, which works into the toothed edges ff H. A rake k k kis sus- pended by the rods k I, which are built into the solid masonry a a. F is a boiler heated by the arch B, and a valve v, at the bottom, is opened or closed by the rod v', to allow the tar to flow through the pipe y y. The coal prepared as already detailed, is thrown into the furnace by the open- ing 0, Fig. 128, and the rakes spread it evenly over the surface of the metal cistern. The tar is admitted by opening the valve v, and as it flows through a pipe n, running the whole length of the rakes, it is more perfectly mixed with the coal, and a smaller quantity is sufficient to make a uniform mass. When the cistern is in the position indicated by the arrows, Fig. 129, the two scrapers 1 1 1 t are lowered together, and they carry the coal forward ; BRIQUETTE MANUFACTURE AT BLANZY. 2IS •when the cistern has made f of a revolution, the two trap-doors « s are opened, and the mass falls down into the receptacles P P. This warm mix- ture of coal and tar is removed through the doors Q Q, and pressed into bricks by a hydraulic machine. Fig. 128. Another modification consists in filling a series of moulds fixed on a moveable table, and by a mechanical contrivance forcing the bricks out of the mould at the same time. Fio. 129. Mr. "Wood proposed to make artificial fuel by mixing either coke or coal sufficiently small, in a heated state, with tar or pitch, in a common pug- mill, after which the mixture may be moulded in the ordinary manner. Chagot's Artificial Fuel. — In the process for the manufacture of artificial fuel, by MM. Chagot and Co., of Chalon-sur-Sa6ne, common coal- tar is mixed with small coal or carefully selected peat, in the proportion of 10 to 50 of the former to 100 of the latter. A certain quantity is then introduced into the still, shown in Fig. 136, where a represents the body of the still, with a discharge pipe and cock h, and an agitator inside c, driven by machinery at d. The cover is double, the inner being composed of sheet- and the outer of cast-iron, with a condensing worm /, supplied with cold water from a cistern at e, and discharging the products of distillation ii6 BESSEiMEE'S PATENT FUEL. at g. The usual products, naphtha, &c., distil over, leaving the pitch behind, which is run off, allowed to cool, and reduced to powder. Fjg. 130. This pitch is ground and mixed with small coal, which has been previously dried on a flat surface at h, heated from below by the flues I. As soon as the material has been sufficiently incorporated, and the whole ren- dered somewhat soft by the heat, it is removed into moulds, and subjected to hydraulic pressure. This is a very simple and obvious method of working up these waste products. Bessemer's Patent Fuel. — ^The following patent process for con- solidating refuse coal-dust is the invention of Sir H. Bessemer, from whose specification the following description is borrowed. It is found that when coal or coal-dust is heated up to a temperature of 500° or 600° F., it becomes softened, the bituminous portions undergoing a degree of fusion sufficient to cause the small pieces to adhere together. It is this peculiar property of partial fusion in coal that Bessemer makes use of as a means of forming, by pressure, consoKdated blocks or masses of coal, possessing the characteristic properties of the coal from which they are formed, but which have the additional advantage of being in pieces of uniform size. Instead of forming the soft coal into large unwieldy masses, as usually practised in the manufacture of artificial fuel, and which require to be broken into pieces before use, producing much small coal or dust, it is made at once into small cylindrical bricks, of a size well adapted to furnaces or domestic use, while the trouble and loss of breaking is prevented, and a most convenient fuel obtained. The machinery or apparatus employed for this purpose is represented by the drawings on Plate III. Sheet A, p. 224, where Fig. I is a longitudinal elevation of a furnace, and an end elevation of pressing machinery. Fig. 2 is a plan of the same. Fig. 3 is a longitudinal section of the furnace on the line a 5 of Fig. 2. Fig. 4 is a cross section of the furnace, and longitudinal section of the pressing machinery on the line c d oi Fig. 2. Fig. 5 is a side elevation of the pressing machinery, and an end elevation of the furnace ; and Figs. 6 and 7 are details of the travelling chain-bed, on a larger scale. In this apparatus, the furnace for heating and softening the coal, the machinery for pressing it, and the steam-engine which produces the required motive power, are all combined, and constitute one apparatus ; and as the BESSEMEE'S PATENT FUEL. 217 products of combustion will pass off from the furnace at a high temperature, it is intended that this surplus heat shall be applied to the generation of the steam required by the engine ; for which purpose, a steam boiler, provided with suitable flues, should be set as near as convenient to the end a* of the furnace a, where it will be perceived that an opening is left at b, Figs, i and 3, for the purpose of allowing the heated matters from the furnace a to pass into the flues of the steam-boiler, the arrangement of which is so well understood as not to require detailed description. The furnace a is of the reverberatory kind, and has a fire-place at c, pro- vided with fire-bars d, and doors; efis an endless chain-bed, of pecuhar construction, passing over polygonal drums g, mounted on axes h; the horizontal position of the chainyis ensured by small iron rollers i, which support it at short intervals; the rollers i are provided with axes, which work in iron sockets let into the side-walls of the furnace ; as also the axes h* of the polygonal drum g*. The chain-bed consists of a number of iron bars of about 30 inches in length, notched on each side, and fitting into each other in a similar manner to a common hinge-joint, and like the hinge, it has a pin passing entirely through it, and thus forms a joint capable of folding over the polygonal drums g, and also of presenting a nearly flat sur- face on the upper side (see Figs. 6 and 7, where a part of the chain-bed is shown on a larger scale). Near the end of the furnace farthest from the fire, a hopper j is fixed, into which the small coal is thrown ; this hopper has a roller k, with leaves projecting from it, working in a cylindrical part formed in the hopper. The roller k is mounted on a shaft I, which tui'ns in bearings formed in the bosses cast on the sides of the hopper J. The shaft I is also supported by a plummer-block n, and carries on its outer end a drum m, which receives motion from the strap o, and causes a regulated quantity of the small coal to pass from the hopper, through the opening p, and fall upon the endless chain-bed in a thin layer ; the motion of the chain- bed in the direction of the fire-place c will bring the coal along with it, and discharge it into the hopper r. To prevent any portion of the coal that may stick to the chain from being carried back again, a scraper s is made to press its edge against the lower part of the chain ; the scraper is mounted on an axis, and has a lever and ball q, the weight of which presses the edge of the scraper against the chain. It will be seen that the fire-bridge t rises sufii- ciently high to protect the chain from the violent action of the fire, and it at the same time forms one side. of the hopper or receptacle r. A break is shown in the drawing, to denote that the furnace and chain- bed are to be made longer than is there represented : from 30 to 40 feet of bed will be found to answer well. When a fire is made in the fire-place c, the heat will be reverberated on to the thin stratum of coal upon the chain-bed, which as it first enters from the hopper is subjected to the lowest temperature of the furnace, and brought progressively into the hotter part, near the fire-bridge ; while new portions of coal are deposited upon the chain-bed, as it passes under the hopper J, which are in turn carried towards the fire-bridge. The increased temperature to which it is thus subjected will cause the coal to soften, and commence to give off some of its volatile constituents, which, when inflamed, add to the action of the furnace. The extent to which the fusion of the coal is carried may be regulated by the speed at which the chain moves, and also by the state of the fire : the small coal being thus softened by heat, and delivered in a regular and con- tinuous stream into the hopper r, is then to be pressed by an apparatus constructed in the following manner : — A, is a strong bed-plate or frame, forming a sort of rectangular box having a flange a', extending around the upper side, and another flange at the lower side connected to the upper one 2l8 BESSEMEE'S PATENT FUEL. by ribs A^, and dividing it into panels ; externally, upon the upper flange of the bed-plate, are bolted the plummer blocks b, which support the trunnions of an oscillating steam cylinder c, which, with its steam-pipes, slide-valve, and valve-gear, may be constructed in the ordinary way ; D is a one-throw crank .of great strength, working in plummer blocks E, and carrying on one end the fly-wheel F. The piston-rod G of the steam-cylinder is connected to the crank by a jib-head G*; there is also connected to the same crank-throw a connecting-rod h, having a double jib-head, so as to take hold of the crank on each side of the piston-rod G ; the other end of the connecting-rod h is jointed at h* to the cross-head i, which moves in slots formed in the guides J J, which are bolted to the upper flange of the bed-plate A. One end of the bed-plate A passes through the lower part of the furnace a, and has bolted to it at that part a massive piece of iron K, with two cylindrical holes bored entirely through it parallel to each other, and which for distinction are termed the pressing-cylinders ; the piece k is held firmly in its place by bolts, and is moreover prevented from moving by projecting pieces k*, which abut against the flanges of the frame a ; the upper side of the piece K has an opening or hopper r* through which the softened coal falls into it. There are two plungers i. L fitted to the cyUnders, and keyed into the cross-head I, so that the revolution of the crank by means of the connecting-rod h, and guides J J, will produce a reciprocating motion of the plungers l L. The crank D has keyed upon it at one end a bevelled pinion m, working into a bevelled wheel N, which is mounted on a shaft p, supported by plummer blocks Q Q ; and at the other end of the shaft v there is a spur-wheel R ia gear with another wheel s on the axis h of the polygonal drum g. This axis h also carries a drum t, over which the strap o passes and communicates motion to the roller k, and thereby regulates the supply of coal upon the chain-:bed. The action of the apparatus will be as follows. Steam having been got up in the boiler by a fire made temporarily under it for that purpose, and the fire lighted in the fire-place c, the working of the apparatus will commence whenever a communication between the boUer and steam-cylinder is opened, the rotation of the crank-shaft will put in motion the bevel-wheels m and N,'and the shaft p; and by. means of the spur-wheels a and s, the shaft h of the polygonal drum g will receive a rotetory motion much slower than the crank-shaft, by reason of the difierence in the diameter of the wheels made use of for that purpose, and thus a slow traveUing motion will be given to the chain-bed. The shaft /t-also carries a drum T, which, by means of a strap, gives motion to the drum m and feeding-roller k, and thereby causes a regular supply of small coal to fall upon the chain-bed, as it passes under the hopper ; the reverberated heat from the crown of the furnace acting on the thin stratum of coal upon the bed will cause a partial fusion or softening of its bituminous parts before arriving at the hopper r, into which it falls. While this action is regularly and continuously going on, the crank-shaft of the apparatus will, by means of the connecting-rod h and cross-head i, give a reciprocating motion to the plungers l l, which work in the cylinders k, and pass along the lower part of the hopper r*, and push before them the softened portions of coal into that part of the cylinders marked k^ ; the extreme distance to which the ends of the plungers move is indicated by the letter z. When the crank commences its backward move- ment, the plungers will also recede until they assume the position represented in the drawing. While this retrograde movement of the plungers is taking place, some portions more of softened coal will have fallen down from the endless chain-bed, and have been deposited in the hopper and upon the plungers; but as the plungers recede, as before stated, into the position shown in the drawing, the coal which has fallen upon them will fall off again into the space occupied by them ; and when the plungers again advance, a BESSEMER'S PATENT FUEL. 219 fresh portion will be forced into the cylinders k', but as the plungers move forward an equal distance each time, the portion of coal pushed forward will be forced against the portion of coal left there by the former stroke of the plungers, and not only will it be forced against it, but it will move it farther along the cylinders k^ until the last portion occupies the place of the former one ; and thus, by the continued action of the plungers, fresh portions of coal will be forced into the cylinders k\ It will be observed that the cylin- ders K^ are open at the end, and it is towards this open end of them that each successive portion of coal is forced by the plungers ; the friction of the mass of coal in sliding along the cylinder is very great, and the resistance thus opposed to the motion of the plungers l l causes a powerful compression of the fuel to take place, which is finally projected from the end of the cylin- ders in a sohd and compact state, as shown at w. It has been already stated that the surplus heat of the reverberatory Fig. 131. furnace may be applied to the production of steam for supplying motive power for the working of the apparatus, and in some cases it may be deemed advisable to heat the coal by this process sufficiently to ignite it, and cause a combustion of the more volatile portions, by which more heat will be communicated to the boiler, and a fuel produced having many of the peculiar and valuable properties of coal, but at the same time not possessing sufficient bituminous matter to cake together when used in a furnace or common fire- place ; from the same cause it will not produce a dense black smoke, and will be capable of being used in many cases where coke is now employed. The apparatus described above is preferred when a fuel differing very little from ordinary coal is required, and the heat is only sufficient to cause the necessary adhesion amongst the small pieces and dust. If more jraseous matter is to be removed, or different kinds of coal refuse are to be mingled 220 BESSEMEE'S PATENT FUEL. and heated so as to produce a fuel differing from coal and more analogous to coke, the following arrangement of apparatus is employed. In order that the volatile products given off by the coal while it is under- going the softening process may be utilized, as well as those portions which are purposely expelled in order to modify the quality of the fuel, and enable it to be made in lumps of definite lengths, an apparatus is constructed in which the retort furnace for heating the small coal, the pressing machine for solidifying the fuel, and the engine for producing the motive power, are combined so as to constitute one apparatus, as represented in the drawings on Sheet B, Plate III., page 224, and Figs. 131 and 132, where — Fig. I, Plate III., page 224, Sheet B, is a longitudinal elevation with the steam-cylinder omitted. Fig. 2, a plan of the same. Fig. 131 shows, firstly, a longitudinal section on the line a b of Fig. 2, with the position of the steam-cylinder ; and secondly, a longitudinal section on the lines c d of Fig. 2, Plate III., page 224, and e f of the sketch on p. 219. Fig. 132 shows various sections of the pressing apparatus at different stages of the pressing process. ^ FiQ. 132. In the furnace a is fixed the rectangular vessel or retort b, which is shown broken through, to indicate that its, length should be greater than represented in the drawings ; about 30 feet in length will be found to answer well ; it should (for convenience of putting up) be made in three lengths united by flanges, and the joints made tight with iron cement ; one end of this retort projects from the furnace, and overhangs a part of the pressing apparatus. The retort has a partition b^ extending nearly the whole length of it, and in a tangent line with the upper surface of the polygonal drums c and d, over which two endless chains e and y are made to pass (see Fig. 2 on Plate III., p. 224, and Fig. 131); the chains c and d are connected together by broad plates of iron g, with flanged ends, which are riveted at h to the single links of the chains ; the edge of the plates g, which project beyond the chains, is bevelled so as to form a scraper ; the polygonal drums c and d have projec- tions i formed upon them, which fall into the spaces between the double links of the chains, and ensure the motion of them when the drums and d are turned round. On the upper side of the retort there is fixed a hopper j; the lower part of the hopper, in which the coal-dust or small coal from which the fuel to be formed is placed, is made to fit closely to the leaves or ribs projecting from the feeding drum k ; there are bosses I formed on the sides of the hopper, in which the shaft n of the feeding-drum revolves ; there are also bosses (not seen in the drawings) formed on each side of the retort EESSEMEE'S PATENT FUEL. 221 for the axis of the polygonal drum c to revolve in ; and on the outer project- ing pai't of the retort are formed two other bosses o and p for the axis r of the polygonal drum d to revolve in. One end of this axis is elongated, and passes through a stuffing-box formed on the boss fi, so that none of the volatile matters within the retort can make their escape at the part through which motion is transmitted to the interior. The action of this part of the apparatus is as follows : — A fire having been lighted in the fire-place s, the heat passing under the retort escapes with the products of combustion at the open end of the flue ^, where it may be made to circulate about a steam-boiler, for the purpose of generating the motive power required to work the apparatus. It will be preferable to set the retort so that the heat may ascend a narrow space between the sides of it and the brickwork of the furnace. An enlargement of the fire-chamber is shown at s^, for the purpose of transmitting radiant heat to the under-side of the projecting part of the retort. The temperature of the furnace having brought the retort up to a heat approaching redness, the feeding-drum is put in motion, when the small coal or coal-dust will be deposited upon the shelf Ji ; but the motion of the chains and scrapers in the direction indicated by arrows, will move it along the shelf ; and as each scraper comes in turn». under the feeding-drum, the coal which has fallen between each of them wiU be carried forward to fhe end of the shelf 61*, off which it falls on to the lower and hotter part of the retort, and, as before, occupies the space between the scrapers. It will be observed that the entire weight of the chains and scrapers rests on the bottom of the retort, so that by their con- stant passage over it, the coal is prevented from sticking to it, and rendering its interior surface uneven. The action of the scraper not only impels the coal forward, but turns it over as it passes along, so as to present fresh portions of it to the heated surface of the retort, and thus ensure an equal effect on the whole of the coal-dust, which, becoming softened, is moved in that state over the opening I?, in the lower side of the retort, and falls into the receptacle t, where it is submitted to the following operations. A is the foundation-plate or framing of the pressing apparatus : it is a sort of shallow box, having a flange a^ around its upper edge, connected to the lower flange by vertical ribs a", which divide it externally into panels, the interior portion of the framing being ako divided by ribs A^, by which its strength is increased. Upon the flange a' are bolted the plummer-blocks B, which support the crank-shaft c, made very strong to withstand the strains to which it is subjected. The crank has only one tJhrow formed on it, in the centre of which is attached, by a gib-head D, the piston-rod E of the oscillating steam-cylinder P. The steam-cylinder, with its induction and eduction-pipes, slide-valve, and other necessaryappendages,may be constructed in the usual way. These parts have been omitted in all the figures, except in Fig. 131, where the steam-cylinder is represented in the position it would occupy at the particular part of the crank's motion there represented. It will be observed, that the steam cylinder is placed, with its axis, in a line vertically over the crank-shaft, and is there supported by trunnions G, work- ing as usual, in plummer-blocks bolted to the two frames H h; these frames have lugs cast on them at h*, through which stretchers are to pass in order to steady them ; the frames H are bolted at foot to the flange a' of the bed-plate. In order to regulate the motion of the apparatus, the fly-wheels i i are keyed one on to each end of the crank C. A stout connecting-rod j is made with a double gib-head J*, to embrace the gib-head D, and thus to receive motion from the same crank-throw. The other end of the connecting-rod j is jointed by a gib-head and pin to two lugs K*, which project from the stout cross-head k ; the ends of this cross-head slide in guides l l, which, are 222 BESSEMEE'S PATENT FUEL. secured by bolts to the flange a^ of the bed-plate. There are three plungers M M M keyed into the cross-head k, and work in cylindrical holes, bored truly through the massive block of iron n ; this block n is bolted to the bed-plate by a flange n*, and is keyed up between steps z, cast on the bed-plate. The upper part of the cylinder block n has a large opening n' made in it, through the bottom of which the plungers m move ; and immediately over the opening N^ is the receptacle into which the softened coal falls from the retort. The cylindrical holes in the block n have another set of plungers p p p, working in the opposite end of the holes to that occupied by the plungers M m m. On the flange a^ of the bed-plate are bolted two guide-bars q and r, having holes bored in them of a size to fit the plungers p p p, which are made long enough to work through both these guides ; so that when the plungers P p p are entirely withdrawn from their respective cylinders in the block n, they will be so guided as to re-enter them without difficulty. The plungers p p p are keyed to a cross-head s ; on the ends of the cross-head s there are fitted with gib-heads two long connecting-rods t (see Fig. 2, Plate I., as they are omitted in the rest of the figures). The opposite ends of the connecting- rods T are provided also with gib-heads, and work on crank-pins u, which project from one of the arms of each fly-wheel 1 1. These crank-pins u u are so placed with reference to the central crank-throw c that the latter forms an angle of 45° to the crank-pins ; that is, the one is one-eighth part of a circle in advance of the other, and thus the action on their respective plungers will be such that they will alternately approach and recede from each other at each end of their respective strokes. It has already been described how the small coal is made to traverse the retort and be deposited in the receptacle. The means whereby the requisite motion is given to the chain and feeding-drums is as follows : — Over one of the fly-wheels i a strap is passed, which works upon a drum v on the shaft w ; on this shaft w there is a worm x which works on the upper side of the worm-wheel y, which is keyed on to the shaft r of the polygonal drum d; the shaft w also carries another worm i, which works into the lower side of the worm-wheel 2, keyed on the axis n of the feeding-drum. The shaft w is supported in bracketed plummer-blocks 3 3, which project from and are bolted to the side of the retort,, so that whenever the fly-wheel is put in motion, the intermediate wheels and shaft last described will transmit the requisite motion to the scrapers and feeding-drum. From previous descrip- tions, it will have been understood how the steam-piston, acting on its crank, will put in motion the whole apparatus, which will be regulated by the fly-wheels, and in what manner the cross-heads k and s will be acted on by their respective connecting-rods, and how the set of plungers m m M, and plungers p p p, are made to reciprocate in their respective ends of the block N ; but in order to show more clearly the way in which they are made to approach and recede from each other five sectional drawings are shown on Kg. 132, by which the relative positions of the two sets of ^plungers, with reference to each other at difiierent parts of their stroke, will be seen ; and to render this explanation more clear, we may suppose the operation to commence when the crank-throw c and its connecting-rod are in a horizontal position, and t.he plungers m m m withdrawn as far as possible from the block n. This position is represented at 5, Fig. 132, where it will be seen that the fuel in an un- compressed state has fallen down and occupies the space in the front of the plungers m. If we now make one-eighth part of a revolution the plungers M will be moved forward a little, as shown at 6 and in Fig. 131, where it will be seen that the crank-pins u u have risen up to the horizontal line and brought the plungers p nearer towards the centre of the block n ; if we now give another eighth of a turn to the crank, the plungers n will have advanced a considerable distance, being at half -stroke, and at the same time the plungers BESSEMEE'S PATENT FUEL. 223 p will have receded into their starting position, as represented at 7. Here it must be observed that the soft coal, which was carried forward by the plungers M, is compressed between the opposing ends of the two sets of plungers. In this position of the plungers there is a small space at z {vide 7), where any surplus quantity of coal may squeeze out before it is made to enter the close part of the cylinder, after which they will approach a very Uttle nearer to each other and thus give the final pressure. If another eighth of a revolution is now made, the- relative positions of the crank and crank-pins will give a quicker motion to the plungers P, which will commence receding from the other plungers M, and thus leave no pressure on the solidified lump of coal X ; were not the pressure thus relieved, the lump of coal as it merges from its cylindrical hole in the block N would be broken, there being no longer any circumferential support for it. This position of the apparatus is shown at 8, Another eighth of a turn will complete a single stroke of the plungers M, and have entirely expelled the block of coal x, which is represented as falling down at 9 ; the plungers P have receded still farther, and allow ample space for the block of fuel to fall. Another eighth of a turn will commence the return stroke of the plungers, and by following on in the same way until one complete revolution is performed, the respective plungers wiU. again have resumed the position represented at 5, and be ready to renew the operation. If three plungers are made use of, as here represented, three blocks or cylinders of fuel, of equal length and diameter, will be formed at each com- plete stroke of the engine. As there is a tendency in the block of fuel to stick to the plungers M, a detaching frame is placed at the end of the machine where the blocks are expelled. 4 4 are thin bars of iron fixed on an axis 5, the ends of which work in lugs 6 on the guide-bar r; the other end of the bars 4 4 are connected together by a rod 8, and upon the cross- head s there are bolted two small frames 9 9 which carry rollers 10; upon these rollers the bars 4 4 rest, and when in the position shown in Fig. 131, the bars are supported a little distance above the plungers p; but when the cross-head s moves backward, and allows the blocks of ooal to be projected outward by the plungers M, then the roller will pass under the inclined part of the bars 4*, when they wiU descend by their own weight, and the rod 8 will come in contact with the blocks of coal and detach them from the ends of the plungers ; if they should adhere, the reverse motion of the cross-head s will again raise up the bars 4 in readiness for a repetition of the process. From what has been before stated in reference to the softening process by heat, -it will have been understood that the coal-dust may be made to traverse the shelf 6^, where it will receive a preparatory heating, and after- wards traverse the bottom of the retort so quickly as to produce such a light effect on the bituminous portion of the coal as only to soften it a little and render it fit for the operation of compressing into solid lumps possess- ing the general properties of the coal from which it was produced. But one of the great objects of this apparatus is to alter and modify the com- position of the resulting fuel by driving off certain of the volatile consti- tuents of coal, and thereby rendering such fuel more fitted for certain pro- cesses in the arts than ordinary coal. To efiect this object, the speed of the feeding and polygonal drums may be I'egulated so as to subject the coal to any assigned period of operation, and the intensity of the fire being also regulated, the extent to which the distillatory process is carried will be under perfect control ; the gaseous matter given off from the coal as it passes into the hottest part of the retort over the fire-plate s, will have to pass over the surface of the coal which is advancing in that direction, and help to heat it, while it also assists in transmitting heat to the under side of the shelf b\ It will ascend through the opening 6'*, and pass along over 224 OTHER AKTIFICIAL FUELS. the coal-dust spread upon the shelf, and farther assist in heating it, and finally make its escape through the pipe u. This pipe should have an elbow- descending in the manner usually adopted in gas-works, and known as the hydraulic main. In this vessel, the liquefiable portion of the volatile matters will be condensed, and the gas may be passed into a gasometer, where it may be stored and used. The fuel resulting from this partial distillatory process will be found to be less fusible in the furnace than ordinary raw coal, and consequently the caking in the furnace will be prevented. In order to facilitate the evolution of gaseous matters from the coal at as low a temperature as possible, and to increase the density of the com- pressed fuel, an air-pump, constructed in the manner generally employed for exhausting sugar vacuum-pans, is used. The pump is connected with the pipe u, Sheet B, Plate III. (opposite), and by the application of steam or other motive power the retort is kept in a state of exhaustion, which should, if possible, be equal to 24 or 25 inches of mercury in the barometer; the effect of this exhaustion is to cause the liberation of the gas from the cells and interstices of the fuel, and to render it more dense and compact when pressed. When the air-pump is used, the eduction valves must be made to communicate with the hydrauUc main, so that the gaseous matters pumped out may pass off into the gasometer. Instead of applying fire directly to the under side of the retort, as shown in Sheet B, highly heated steam may be used for the purpose of heating and softening coal, to be afterwards pressed into lumps or cylindrical pieces. For this purpose, a set of cast-iron pipes is arranged in a furnace in the same way as is now commonly used for heating air for hot-blast furnaces, and also for heating steam. Into one end of this series of heating pipes, the waste steam of the engine is allowed to pass, and the pipes being kept at a red heat, the steam will acquire a very high temperature, and in that state is to be supplied to the interior of the retort for the purpose of softening the coal ; in this case, the retort, which may be made in the same manner as that represented in Sheet B, but will not require any fire-place or flue beneath it, but should be enclosed in brickwork or other bad conductor of heat ; the pipe which conveys the steam should enter at the hopper t, the steam escaping with the gases through the pipe u into the hydraulic main, where condensation will take place, the gases passing off to the gasometer. In addition to the processes described above, the following plans have also been suggested or patented for preparing artificial fuel : — Bell proposed to use pitch, asphalte or bituminous matters, and small coals in a pug-mill, whose knives and shafts are hollow, so as to be heated with steam, and then moulded. Cobbold agitated peat in water by means of machinery, so as to separate the earthy matter, and allow the peat afterwards to subside. Dobree proposed to heat ground small coals, breeze or cinders, and pitch, (fee, in close vessels with high-pressure steam, which will so amalgamate the whole that they may be moulded. Godwin proposed to make bricks from mud, or clay, ground up with pitch and coals ; and Greary to melt pitch, coals, tar, sawdust and clay together for the same purposes. Holcombe proposed to run a mixture of tar, pitch, dead-oil, &c., over bricks formed of limestone or other porous materials. Mohun mixed alum, nitre, peat coke, &c., in a pug-mill, and afterwards compressed them into moulds. This combination in one substance of an anti-combustible like alum, and a powerful oxidizing agent like nitre, is renlarkable. BESSEMER'S PATENT. Plate m. To face pcLge. 224. OTHER ARTIFICIAL FUELS, BRIQUETTES. 225 Oram used tar, coals, mud, &c., and compressed them into moulds, after being previously carefully mixed and sifted. Stirling used the ordinary materials but exposed the bricks to a tempera- ture of 250° F. afterwards. Warlich heats his bricks in large kilns up to a temperature of 400° or 600° F., to expel all the gaseous constituents, exposing the square bricks, so as to nlake coke in the usual way. Hill's process consists in distilling peat in the same way as wood, and mixing the residual charcoal with the hot pitch, so as to form lumps or bricks on cooling. Lowe saturated dry blocks of peat with tar or other carbonaceous fluids in large cisterns, by means of heat. Holland mixed gypsum, lime or cement with tar or small coals, and com- pressed the mixture into moulds. Buckwell simply employs enormous pressure to form bricks out of small coal, or breeze from coke, whilst Rees submits such materials in moulds to a temperature of 500° to 990° F., which, partly melting, adhere on cooUng and form solid masses suit- able for use. Brooman substituted gutta-percha as the binding ingredient when using the usual materials, whilst Ransome employed a solution of silicate of soda for the same purpose. W. H. Cory, of Cardiflf, inventeel a method of utilizing slack or small coal, which is said to have been in successful operation since 1873. The process (which Percy, however, states was first patented by Mr. John Bethell in 1854), consists in mixing the slack or dust with fireclay and silicate of soda (for bituminous coal, 2 per cent, of clay and 3 per cent, of silicate), and subjecting the block to a pressure of a ton to the square inch of the block surface. The block thus formed is as hard as ordinary coal, and has all its angles rounded to prevent chipping. The surface is glazed by the manner in which the pressure is delivered, and the press turns out 240 tons in twenty-four hours. The blocks require twenty-four hours to become hard and fit for use. During that time, the required chemical action takes place, the clay converting the silicate of soda into alumino-sodic silicate, which vitrifies the block and causes it to be weather proof. A very simple plan was introduced in 1867 or earlier in Austria by Von Stummer-Traunfels, who was engineer to one of the State railways, the locomotives of which used his briquettes. He mixed a certain proportion of farinaceous, amylaceous, or glutinous matter with a certain proportion of fibrous material, and these being boiled together to form a cement were then mixed with coal-dust or small coal, and moulded into bricks. He stated that he found the cost of working the process to amount to two shillings per ton, including cement. Stummer was evidently not the first to use farinaceous material for agglomerating small coal, as Percy refers (p. 465, " Fuel ") to Barker's patents of 1864 and 1865 for the manufacture of artificial fuel by means of mucilage made from any farinaceous substance. But Barker stipulates that the gluten should be first removed, whereas Stummer employs it for its binding qualities. Percy also records that, according to Mr. Prim, a native of Killarney, it was the practice in Ireland previously to the potato famine to boil potatoes unpeeled, and that the stiff pulp obtained by pounding their skins with the addition of a little water, was mixed with coal-dust and sufficient water to make a mixture about the consistency of stiff mortar. The mass was then well mixed, moulded by hand into oval-shaped balls, which were stacked in. a dry cellar for use as fuel for domestic operations. Q 226 GASEOUS COMBUSTIBLES. The processes of Barber and Bethell have been introduced practically in Britain, but the artificial fuel or fuel brick industry has never made any great advance in this country, no doubt on account of the abundant supply of cheap coal. It may come to the front, however, at any time in con- sequence of the efforts made by coal producers to economize in various directions and to improve, by washing, screening, &c., the quality of the slack which they sell. On the Continent, however, it is a well-established industry. Under the name of Peras, artificial fuel made from small coal of screenings, dust, &c , washed, ground, and mixed with thick coal-tar and moulded into bricks under pressure, has been known in France for a considerable time. So also has the moulded charcoal or Parisian coal introduced many years ago by Popelin- Ducarre, and the use of coal briquettes on Austrian railways has already been referred to. The briquettes possess several advantages — they are less friable than coal lumps when properly made, and being of regular shape are more easily stowed. For domestic use they have the advantage of not soiling the hands, and they can be purchased by number, so that a check is kept on the weight supplied. Within the last few years, the manufacture of coal briquettes has attained considerable proportions in South Wales, and during 1886 the deve- lopment of the manufacture commenced in Scotland. This is the outcome of the recovery of large quantities of tar from blast-furnace gases, the tar being of low quality and practically unsaleable for the extraction of benzene or the more valuable hydrocarbons from it. Messrs. Wm. Baird & Co. have started this, for Scotland, new industry at their Lugar Ironworks, South Ayrshire, where the coal-dust or dross used is that of very fine coal known as the Bute Jewel Coal, a good household coal. The dross of this coal is first carefully washed, and is then sorted by passing through screens of five different meshes. Of the classes of sorted fuel, the larger (nuts and peas) are used without further manufacture, but the finer classes are dried and ground, and then mixed with a proportion of pitch powder, when they are compressed into small blocks by hydraulic rams — the pressure exceeding 2 tons per square inch. The result is a brick-shaped block of coal, clean and compact, but yet easily combustible and containing under 3.6 per cent, of ash. The plant at Lugar Works is capable of turning out 200 tons of briquettes per day. GASEOtrS COMBUSTIBLES. Although the practical use of gaseous fuel has been accomplished on any- thing like a general scale only in recent times, yet the knowledge of its value and of several sources of supply dates back nearly ninety years. In 1 80 1, Lampadius proved the possibility of utilizing the waste gases escaping in the carbonization of wood, and in 1809 to 181 1 M. Aubertot employed the waste gases of blast furnaces for roasting ores, burning lime, &c. In the year 1811 or 1812, a patent was granted to Aubertot for the application of th6se gases to metallurgical purposes, and in 1814 he is found advocating the building of suitable furnaces for their employment. A Report communicated to the French Academy of Sciences in May 1842, by MM. Thenard, Berthier, and Chevreul, mentions these facts. Lampadius in 1830, at the Lead Smelting Works of Halsbriicke near Freiberg, attempted to employ the flame of coal-gas in cupelling silver lead ; and in 1837, the use of waste gases was carefully investigated by Faber du Faur, who carried out some laborious experiments at an ironwork in Wur- temburg. These experiments attracted attention widely to the advantages of employing the waste gases from blast furnaces as fuel, and may be said to have led to the present almost general adoptioA of that method of working. WASTE GASES FEOM BLAST FURNACES. 227 The property of burning with flame is common to most of the natural fuels, and is due to the evolution and combustion, at a high temperature, of the combustible gases, carbonic oxide, hydrogen, hydrocarbons, 9 9 85 98.06 1.48 097 I. 57.06 ■'•39 28.61 0.20 a.74 11. 56.64 11.39 28,93 3.04 100.00 100.00 100.00 JOO.OO 100.00 100.00 100.00 100.00 Oxyiien for every loo vols, of nitrogen 4I.» 29.9 30.J 30.6 29.6 40.0 45-0 45-6 Vapour of carbon for every loo vols, of nitrogen 41 -3 29.9 39,6 30.0 29.4 33.0 35-» COMPOSITION OF BLAST-FUENAOE GASES. 237 The height of the furnace of Seraing from the blast to the mouth was 46 feet. The blast was heated to 212° F., and the pressure was 0.05 mill, of mercury. It will be observed that at the corresponding height above the blast, or at 34 to 36 feet in this furnace, as compared with the other two, the gases have very nearly the same composition. The gases from iron-furnaces consuming coal as fuel have been examined at Alfreton, Derbyshire, by Bunsen and Playfair, at nine different levels. Their results were as follows : Height above the blast . 2j ft. I2fl. 13I rt- 16J ft. 19I ft. 22f ft. 25? ft. 28J ft. 3>J ft- S5 35 Nitrogen . 5»-°i S6.Ji, 58.28 60.46 55-49 50.95 52.57 54-77 Carbonic acid lo.oS 8.19 10.8J 12-43 9.10 9-41 942 7-77 Carbonic oiide . 37-13 2S-I9 26.97 19.48 1877 19.32 23.16 20.24 25-97 Marsh gas . ■ . 2-33 1.04 4.40 4-31 6.64 4-58 8.23 3-75 Hydrogen . . 3.18 S.6S 4.92 4-S3 7.62 12.42 9-33 6.49 6.73 Oleiiant gas . 1.38 '-S7 0.95 0.8s 0.43 Cyanogen 1-34 trace trace — 100.00 100.00 100.00 100 00 100.00 100.00 100.00 100.00 100.00 The height of the Alfreton furnace from the blast to the mouth was 36I feet. The blast was heated to 626° F., with a pressure of 6.75 inches of mercury. The most appropriate spot for withdrawing the gases from this furnace would be at about 22f feet above the blast, where the gases have the follow- ing composition : Nitrogen ... . 50.95 Carbonic apiil . Carbonic oxide Marsh gas Hydrogen defiant gas . 9.10 19.32 6.64 12.42 1-57 100.00 The composition by weight corresponding with the above is as follows : Nitrogen Carbonic acid Carbonic oxide Marsh gas Hydrogen defiant gas . 56.3 15-2 21.5 4-2 I.O 1.8 The gases evolved from the anthracite furnaces at Ystalyfera were analysed at two levels by SchafhautI, with the following results : Depth below the coal and mineral 16 ft. I ft. Nitrogen Carbonic acid ..... Carbonic oxide .... Marsh gas Hydrogen Sulphurous acid, with traces of arseniu- retted and phospliuretted hydrogen . 49.844 00.136 18.974 3.212 27.844 trace 54-505 9.546 12.012 2-548 21.278 cm 100.000 100 000 The value of the escaping gases as affording an index of the working of blast-furnaces has been established by the labours of Sir I. Lowthian Bell, and has been fully illustrated in his writings on the subject and in 238 EXAMINATION OF BLAST-FUENACE GASES. those of Prof. Griiner, 0. Schinz and others.* The analyses quoted above have been examined in Sir I. L. Bell's writings in this light, and many others have .been added by him, Mr. C. Cochrane, and other workers in that field, and the chemical and calorific phenomena have been so connected and shown in their relation to one another that it has become possible to calculate within narrow limits of error " the technical useful efiect of any furnace and the econoniiccd effect of furnaces working in any district for which the propor- tions of fuel, ores and fluxes, and the temperature of the blast are known." Griiner in his " Studies " has also emphasized the importance of ascertain- ing the proportion of carbonic oxide to carbonic acid present in the escaping gases of any furnace, and maintains that the ratio -j— i^ these gases is the KjKJ index of the working of the furnace. It is impossible to give in a condensed form any satisfactory account of the voluminous researches and calculations which Sir I. Lowthian Bell has used in explanation and illustration of the complex phenomena of iron smelting ; for these his own writings mvist be studied. He carefully measures the amount of heat generated in the furnace by combustion of the carbon, and conveyed into it by the heat of the blast, and apportions this heat in the amounts required by the several operations conducted by its means. In addition to these considerations, there are investigated the questions of the chemical combinations which take place between the carbon of the fuel and the oxygen of the blast, the carbonic acid formed by combustion and expelled from limestone, and the incandescent carbon, the carbonic oxide, and the oxygen of the iron ore; and the relations which these bear to the quantity and composition of the escaping gases and to the weight of materials delivered into the furnace. As regards the one p6int of the ratio existing in the waste gases between the volume of the carbonic acid and that of the carbonic oxide which they contain. Sir I. L. Bell has said that his observations on the conduct of furnaces smelting Cleveland ore led him to conclude that, when the ratio is I volume of CO2 to 2 of CO, the mixture of gases ceases practically to act on that ore. The largest average proportion of COj he, found was represented by I volume 00^ to 2.09 vols, of CO, but, as a rule, fairly good working is obtained when the ratio is i vol. of COj to 2.20 of CO. The examination of various furnaces of different heights and sizes, and of their gases, ores, temperatures of blast, &c., has furnished data which lead to sound conclusions as to the requisite size of furnace for a given temperature of blast, the quantity of fuel required by ore of a given com- position, and many kindred matters of importance. The part played in these investigations by examination of the chemical composition of the escaping gases cannot be over-estimated, and the result is that the index of the economical application of the fuel in the furnace is found in these gases. The following, which is quoted from a comparison by Sir I. L. Bell between a blast furnace worked with raw coal and one worked with coke, illustrates the importance and usefulness of these investigations : " The chief object of the present communication is to consider the differences between bituminous coal and coke in the smelting of iron, and to compare their respective action. " If we measure the value of these two substances in a calorific point of view when both are fully ,oxidized, there is but little difierence between them ; the value being ascertained by the power possessed to raise the temperature of a given quantity of water. » See, by Sir I. Lowthian Bell, " Chemical Phenomena of Iron Smelting ;" " Chemisti-y of the .Blast Furnaee," " Jour. Chem. Soc." i86q, " Jour. Iron and Steel Inst. ; "" Crookes and KShrig's "Metallurgy ;" Grtiner's "Studies of Blast Furaace Phenomena ;" 0. Schinz, " The Blast Furnace." HEATING POWER OF GOAL AND COKE IN THE BLAST FUENACE. 239 " Full oxidization or complete combustion means, in the case of coke, the conversion of all the carbon into carbonic acid, and in the case of coal its conversion into carbonic acid and water. '■ For the purpose of illustration, a specimen of coal from the Brockwell seam at a South Durham colliery will be taken ; its calorific power will first be estimated in the raw state, and then a similar calculation will be applied to the coke made from the same coal. Composition of Estimated Composition of tbe Coal. Colte from the same Coal. Per cent. Pei- cent. Carbon 81.47 ••• 92.44 Hydrogen 4.57 ... — Oxygen . 5.04 ... — Nitrogen .91 ... — Water . .76 ... — Sulphur Ash . 1.22 i.oo 6.56 100.48 100.00 72.89 20.84 ■76 92.44 ml nil Fixed carbon Volatile above 100° C. (212° F.) Volatile below 100° C. HEAT DEVELOPMENT FROM EACH UNIT OF FUEL.* Coal. Coke. Carbon to carbonic acid . .8147 x 8000 = 6518 calories, .9244 + 8000 = 7395 calories Hydrogen to water . . .0457x34000=1554 „ jiil „ Total developed .... 8072 „ 7395 „ Deduct heat absorbed by ex- pulsion of hydrocarbons, &c. (including deficiency in heat development of C and H through com- bined 0) ... .2084 X 2000 = 417 ,, nil ,, Net heat development . . 7655 „ 7395 n " By these computations it will be remarked that practically the heating power of coal and coke of the composition just given is the same, and the following are the results of a trial recently made on the North-Eastern Railway : " Two lengths of road were selected on the North-Eastern system for the experiments. The same engines were used at both localities in the two sets of experiments ; the trains consisted of the same number of waggons in the trials of coal and coke, and the loads were practically the same also. The trials were continued for one week with each kind of fuel, full loads being taken to the place of shipment, and the waggons returned empty to the collieries. Coai. Coke. One week's trial of each fuel; pounds consumed per train mile . 40.5 ... 41.6 One week's trial of each kind of fuel; pounds consumed per train mi!e+ 37.0 ... 42.2 " The parity of results observed in burning coal and coke on a grate where the combustion is, generally speaking, perfect, is not to be found in blast furnace experience, for the simple reason that the volatile constituents * No credit is taken for the heat evolved by the combustion of the sulphur in either case, because the exact form in which it exists was not determined. Besides this, the heat evolved by the oxidation of sulphur is very small, and consequently its omis.siou does not seriously affect the calculation. The water in the coke is also neglected, but this at Durham is also very iosigriificant in quantity. t The coal in this trial contained only 1.2 per cent, of ash against 7.4 per cent, in the cok In both trials the coal and coke were from the same colliery — viz. , Eldon and West Wylam. 240 GASES FROM COAL AND COKE IN THE BLAST FURNACE. are scarcely at all oxidized in the furnace, and consequently little or no useful effect is obtained from their presence. This statement presupposes that the smelting operation is conducted in a close-topped furnace ; but in cases where the escaping gases are not utilised, the combustion on the mere upper surface of the materials is attended with little or no benefit. "There is, however, another way in which the volatile hydrocarbons might be useful in the blast furnace — viz., as a means of reducing the oxide of iron to the metalhc state. " Reverting for a moment to the action of a blast furnace using coke, this first stage in the operation of smelting iron may be performed by one of two processes. Carbonic oxide generated by the combustion of carbon at the tuyferes may be the reducing agent, in which case carbonic acid is the product ; or else the operation may be effected by solid carbon, in which case ' carbonic oxide is generated. In the latter case, not only does the carbon which has served for the purpose of reduction never reach the tuyeres, and in consequence acts no part in fusing the iron and slag, but since the heat generated by a unit of carbon leaving the furnace as carbonic oxide and as carbonic acid is respectively as 2400 to 8000, there is a great loss in the heating power of the fuel employed. "The statement just made is, of course, an' argument for seeking to obtain as large a proportion as possible of carbonic acid in the escaping gases. Experiment and practice, however, have demonstrated that the power of carbonic oxide to reduce an oxide of iron to the metallic state has its limits ; and that when something like one-third of this gas is saturated with oxygen, i.e., has become carbonic acid, further change is suspended. We have then the carbon gases in their ultimate form composed of one volume of carbonic acid and. two volumes of carbonic oxide. It might, however, be possible to dispense with a portion of the carbonic oxide, and still maintain the reducing power of the mixture by substituting for it a gas also capable of deoxidizing the ore. The hydrocarbons, like the oxide of carbon, are energetic reducing agents ; but it will be seen by a study of the composition of the escaping gases, as well as by a consideration of the quantity of fixed carbon present when raw coal is used in the blast furnace, that they do not render any marked service in the process itself. "I have been permitted to examine with all the necessary care the working of blast furnaces using the celebrated splint coal of the Lanarkshire coal-field. The information thus obtained I propose to employ for the purpose of illustrating the subject of the present paper, selecting for this purpose the performance of a furnace having a height of 74 feet, and blown with air having a mean temperature of 800° F. (427° C). " Numerous specimens of the coal itself were collected, so as to obtain an average sample. This, as well as average samples of the escaping gases, were carefully analysed in the Clarence laboratory, and I would first direct attention to the composition of the coal as thus ascertained : — ANALYSIS OP SCOTCH SPLINT COAL. Per cent. Water given off at 100° C. (212° C.) . 11.62 Carbon ... . 66.00 namely, 53.41 fixed, and 12.59 volatile Hvdrogin 4.34 4.34 „ Oxygen 11.09 11.09 ,1 Nitrogen ...... .94 .94 „ Sulphur* 59 — Ash 5.42 — Total . . . 100.00 Matter volatile above 212° F. 28.96 „ » A portion, probably one-half, of the sulphur Is volatile; but in the calculation this is GASES FROM COAL AND COKE IN THE BLAST FUENACE. 24 1 " As a source of heat, the chemical composition of this coal indicates a great inferiority as compared with the analysis of South Durham coal. Instead of 81.47 per cent, of carbon and 4.57 per cent, of hydrogen, it only contains 66.00 and 4.34 of these substances respectively. Again, while the English coal only shows .76 of water and 5.04 of combined oxygen, we have in the Scotch 11.62 of the former and ir.09 of the latter. Computed in the manner applied to the South Brancepeth coal ante, the heating power of the Scotch splint stands thus : — Carbon to carbonic acid . . . .6066 x 8,000 = ^^:* ANALYSIS OF GAS FROM SIEMENS PEODUCEES. combustible 34-6 Per Cent. by Voiume. Carbonic oxide . 24.2 j Hydrogen . . 8.2 [ Hi diocarbides . 2.2J Carbonic acid 4. 2 I incombustible Nitrogen . . . 61.2J 65.4 100 o This analysis was published by Kraus in 1865 (or i869),t and re- presents the mean quality of gas obtained from the producers at the Plate Glass Works, St. Gobain, France, burning a mixture of -f caking coal and ^ non-caking coal. M. Boistel, in a communication to the Societe des Ingenieurs Civils, dated August 1867, gave the following average composition of Siemens producer gas : — Carbonic oxide 21.5 to 24. per cent, by volume Carbonic acid . 4. ,, 6. „ „ Nitrogen . 60. „ 64. ,, , Hydrogen 5.2 „ 9.5 Hydrocarbons . 1.3 „ 2.6 „ „ Referring to the St. Gobain analysis, Mr. C. W. Siemens made t the following remarks regarding the action of his cooling-tube. "The gas jising from the producer at a temperature of about 1100° F. is cooled as it passes along the overhead tube, and the descending column is consequently denser and heavier than the ascending column of the same length, and con- tinually overbalances it. The system forms in fact a syphon in which the two limbs are of equal length, but the one is filled" with a heavier fluid than the other. The height of cooling tube required to produce as great a pressure in the flue as would be obtained by placing the gas producers, say, ten feet deeper in the ground, may be readily calculated. The temperature of the gas as it rises from the producers has been taken as 1100° F., and we may assume that it is cooled in the overhead tube to 100° F., an extent of cooling very easily attained. The calculated sp. gr. referred to hydrogen, of the gas of which I have quoted the analysis being 13.14, we obtain the following data : — lb. Weight of the gas per cube foot at 1100° F. . = .022 „ „ „ 100° F. . = .061 atmospheric air per cube foot at 60° F. = .076 and from these we have, on the one hand, the increase of pressure per foot of height, in a flue rising directly from the gas producer, ■= .076 - .022 = .054 lb. per square foot ; and on the other hand, the excess of pressure at the foot of the downtake from the cooling tube over that at the same level in the flue, leading up from the gas producer (for each foot in height of the cooling tube), = .061 - .022 = .039 lb. per square foot. The height of the cooling tube above the level of the flue that will be * See " Jour. Chem. Sec," 1868, p. 279, Siemeus on the Regenerative Gas Furnace, t See Memoirea de la Societi dea Jngin. Cieils, No. 28, 1874, P- 782- i Op. at. ante. COMPOSITION OF PEODUCEE GAS. 281 sufficient to produce the required pressure, equal to 10 feet of heated gas column, is therefore, :OS4 •039 10 feet = 13' 10", or say 14 feet." M. Sylvain Perisse, in a paper in the Bemoires de la Somite des Ingenieurs Civils (No. 28, Oct. to Dec. 1874, pp. 752, 812) on the Ponsard furnace has given the following analyses of gas as generated in Ponsard producers which are of the Siemens form with some slight modifications : — I. II. III. IV. i Carbonic oxide Carbonic acid . Nitrogen Hjdrogen and hydrocarbons . 21.0 6.0 61.0 12.0 25.0 4.0 60.0 II. 22.5 4-5 57.0 16.0 22.0 4.4 S2.0 21.6 24.0 4.0 5S-0 17.0 By calculation. By difference. Volumes 1 00.0 lOO.O lOO.O lOO.O 100. I. The coal used was a caking coal, which on analysis, after drying at 110° C. (230° F.) gave 79 to 81 per cent, of coke, and 21 to 19 per cent, of volatile matter. The quantity of ash varied from 9 to 18 per cent. Cinders amounting to about ^ of the quantity were charged with the coal. Cold air was used, but the producer was worked fast. II. The producers were charged with f of good coal and f cinders from other fires. Ordinary producer with cold air. Temperature of gas about 650° 0. III. Producer worked with forge coal giving 73 per cent, coke, well formed but feebly swelled, and 27 per cent, volatile matter. The coal contained 20 per cent, ash, and was used without admixture with cinders. The gas escaped from the ordinary producer at 850° C. Water was allowed to trickle under the gi-ate from a tap. IV. Hot air from the Ponsard recuperator was supplied to the producer, but the air was not freed from moisture. The coal was a gas coal giving 65 per cent, of a feebly formed coke, and 35 per cent, volatile products. Ash 15 to 20 per cent. Temperature of the gas equal to that of melting copper. v. Sarre conditions as No. IV., but with the air dried. ANALYSES OF GAS PRODUCED FEOM PEAT. Carbonic oxide Carbonic acid . Ponsard Producer. VI. VII. 21. ... II. ... 23- No. VI. Peat very wet, containing 50 per cent, water, but there was a slight loss of water, while it was kept in the boxes before charging. VII. Wet peat, containing 28 per cent, water. The peat used in VI. and VII. gave after desiccation : — Volatile matter . . . 58.5 per cent. Solid (including ash) . 41.5 ,, Ash amounted to 8 per cent. 282 COMPOSITION OF PEODUCEE GAS. ANALYSES OF GAS PRODUCED FROM COKE AND WOOD CHARCOAL. From Siemens' Producers with Coke. Ebelmen's with Dried Air. With Wood Charcoal with Moist Air. Carbonic oxide Carbonic acid Nitrogen Oxygen Hydrogen 26.0 67.S as not given. 33-3 634 2.8 27.2 S-5 53-3 14.0 — 1 00.0 1 00.0 The first of these analyses is from the work X)f M. Felix Leblanc, on the Gas Works of the Compagnie Farisienime. ANALYSES OF GAS FROM WILSON PRODUCERS. I. II. in. Carbonic oxide Marsh gas (CHJ .... Hydrogen . . . . Nitrogen ... . . Carbonic acid 26.89 I -45 ii.SS S6.11 4.00 2341 2.22 13.82 55-86 4.69 23.60 3-oS lO-SS 57-55 5-25 Volumes Total percentage of combustibles 100.00 39-9 100.00 39-45 100.00 37-2 No. I. Analysed by Pattinson and Stiead, of Middlesbro', from producer using Durham coal. No. II. Analysed by Pattinson and Stead, being average of 6 samples taken during an hour from a producer working on fine Yorkshire slack. No. III. Analysis by the Director of the Hainault Glass "Works, Bou^ near Charleroi. Producer using Belgian coal. The following analyses of gas from Wilson producers were made by the engineer to the Plas Power Colliery, Wrexham, in connetjtion with some comparative tests of gas firing as against hand firing for the steam boilers of the colliery : — Description of coal used, IV. refuse, V. and VI. best coal. ANALYSIS OF GAS. IV. V. VI. Carbonic acid Oxygen . . .... Hydrogen Carbonic oxide ... . . Marsh gas Nitrogen 7.14 0.00 12. IS 19-83 3-61 57-24 4-'l , 0.00 12.42 26.48 51.06 6.26 0.00 14.68 23.98 4.72 50-36 99-97 9998 100.00 IV. Pressure of gas in producer, 20 millimetres. Temperature of gas in producer, 960° C. ,, „ above gas valve at boiler, 740° C. ., ,, fuel of producer, 1300° C. V. and VI. Pressure of gas in producer, about 22 millim. Temperature of gas in producer, 600° C. ,, ,, at gas valve at boiler, 450° 0. In these latter trials, the column of fuel in the producer was kept 2 feet COMPOSITION OF PEODUOEK GAS. 283 higher than in No. IV., and a larger amount of steam was allowed to enter the producer by the steam jet, at a lower velocity than in No. IV. The following analyses of producer gas were published by the late Mr. Magnus TroUius, chemist to the Midvale Steel Co., Philadelphia : * — Notes. Philips Producer at Hoopes and Townsend. Siemens Producer Midvale. xa and ib from differ- ent producers, but at the same time, aa md 3&, ditto. 3a and 36 Irom the same producer. The last two analyses from Midvale belong to- gether, being taken with half an hour interval. " 1% = i 1-5 g Ip i s . p 1 11 . No, 3& taken lo Minutes after 3a with Air shut off aa far as passible, and only Steam let ou. le-i 111 1^ is II to 3 Samples taken just after coolinjf down Fires with Water from below. Carbonic acid, CO, Ethylene, C1H4 . . Carbonic oxide, CO Hydrogen, H Marsh gas, CB^ . ^ffiituqgen^differeoce)^ ^ Totals Calories per 100 litres at 0° and 760 mm. . Flame temperature 3-9 "7-3 8.7 30.0 8.7 1.2 61.4 9-3 8.6 ».7 63.9 7-5 16.0 15-3 1.9 59-3 8.0 15-5 14.9 6i.6 6.1 22.3 28.7 I.O -4X^ 5-7 ■9 15-4 '■5 23.6 60 3-° -65.^ 5-9 9.8 24 64.2 lOO.O 100. lOO.O 100.0 100.0 zoo.o ^00.0 .. 100,0 100.0 93.966 1,619 & l%7s^ "1.474 1,706" 92.620 1,613° 164,164 1,846 "6 753 7,^76'.'^ 103,843 1,642"=^ The following comparative table of properties and composition of various kinds of gaseous fuel is from a paper by Mr. Alfred Wilson (" Proc. Cleveland Inst, of Engineers," June 9, 1879) : — Composition of 100 Parts by Weight. Percent- lbs. of tde lb. Units d. Combus- er Constant BAfure. n No. Oases. age of Combus- Air to Burn .at" tible. lib. II g' N. H. CO.. CO. CH,. C.H4. Cen Pro tion ^1 I. Blast furnace. Scotch . 48.J 0.9 2i. 7 29.24 30.14 0.96 946 1,010 1. Blaat furnace. Askam . S«.S9 C.14 ■3.47 3380 — — 33.94 0.9 859 1.873 3. Blast furnace. Cleveland 58-S4 0.06 l4-3a 27.03 — — 27.09 0.87 669 ■.9^J 4. Producer gas. Siemens . 64.'! — 6.9S 14.92 0.89 1.73 J8.54 1.17 1,038 1,000 i- Producer gas. Siemens . PixtdQieKlas. 'Wilson . 63.22 0.6J 8.,l 'S-91 ■•4S 18.07 1. 11 1,036 ».95J t). bi.7 0.90 6.01 "Q.fS 0.91 — 31.39 1. 10 1.139 1,128 1- Producer gas. Wilson . 61.84 i.ii 8.2, 16.33 ■•43 — 18.87 1.18 1,201 1,204 H. Retort made town gas — 8..; 18.61 56.10 ■ J.ll 100.00 ■ J. 60 11,623 3.171 NoTEB. — No. 1 is from Sir I. Lowtbian Bell's "Chemical Phenom. of Iroh Smelting," p. 313 ; No. 2 is an analysis by W. Crossley ; Kos. 3, 6, and 7 are by J. E. Stead, of Middles- bro' ; Nos. 4 and j are by 6. J. Snelas. From a paper published by him in the Journal of the Society of Chemical Industry,! the following average analysis of gas from Mr. Sutherland's producer is given by the inventor himself : — Carbonic oxide Carbonic acid . Nitrogen Hydrogen 34 to 30 per cent. ■2 >. 2-5 55 „ 60 4„ 8 Mr. G. Beilbyt gives the following as the composition of the gas from the Young and Beilby apparatus for the treatment of coal in order to obtain all the nitrogen as ammonia. He remarks " the dross used in these retorts contains nitrogen equal to 165 to 170 lbs. of sulphate of ammonia per ton. • " Trans. American Inst. Mining Eng.," Feb. 1883. t Feb. 1883. t " Jour. Soc. Ohem. Ind.," 1884, p. 216. 284 COMPOSITION OF PEODUCEK GAS. Bcsults have been regularly obtained, yielding from 90 lbs. to 125 lbs. of sulphate per ton, or say 60 to 70 per cent, of the total nitrogen. The quantity of steam used has varied from 2500 lbs. to 3500 lbs. per ton of dross, equal to 250 to 350 gallons of vaporised water, so that the proportions of coal to steam now stand, i coal to i^ steam. The composition of the incondensable gas varies somewhat according to temperature, air supply, (fee. A sample showed the following percentage composition, by volume : — Carbonic acid Carbonic oxide Marsh gas (CHJ Hydrogen . Nitrogen 1&6 8.1 2-3 286 444 With regard to this analysis, Mr. Beilby remarks that it indicates a rather excessive air supply, as the point aimed at in using this apparatus is to obtain a consumption of one-half of the fixed carbon with air and the other half with steam. Corrected to the results produced with such an admission of air, the composition of the gas would be : — Carbonic acid . . . . 21.32 Carbonic oxide . 10.72 Marsh gas, &c. . nil Hydrogen . 37.19 Nitrogen ... . 30.77 Elsewhere* Mr. Beilby has explained that in decomposing steam by incan- descent carbon according to the equation + H,0 = CO + H, (1.) the nitrogen contained in the mineral would not be recovered as ammonia, in consequence of the high temperature at which that reaction takes place. In his apparatus, a much lower temperature is maintained, and an excess of steam or other neutral gas (or of hydrogen according to Mr. Tervet's method) is used, the result of such lowering of the temperature being the formation of carbonic acid, thus : — 3C + 9H3O = 00 + 2CO2 + 5H, + 4H2O (excess) (II.) At the same time, the conditions are realized for the formation and pre- servation of ammonia from the nitrogen of the fuel, and as this is the main object of the Young and Beilby plans it is perhaps scarcely fair to class their apparatus with others whose object is the production of heating gas. The reactions expressed by the preceding equations, excepting the excess of HjO in (II.) show what takes place in the formation of so-called " water gas," that is, the gas resulting from the decomposition of steam by red-hot carbon. According to the temperature employed in the process, the mixture of gases contains more or less carbonic acid, but the first equation is of course what is aimed at by those who wish to make water gas for use as fuel. In practice, however, it has very seldom been attained, although of late years there have been some approximations to it. Dr. Percy (" Metallurgy," vol. Fuel, p. 418) gives the following analyses of water gas made in the apparatus patented by Mr. J. Dawes, who he believes (p. 516) was the first to apply the mixture of gases so obtained : — f " Proc. Inst. C.E.," vol. Ixxvii. pt. iii. COMPOSITION OF PEODUCEE GAS. 28$ COMPOSITION PER CENT. BY VOLUME OF GASES RESULTING FROM THE ACTION OF STEAM ON EED-HOT COKE. s^ ■ ■ >t"s) ...»:'. Carbonic oxid I . 31-86 ... 29.30 Carbonic acid 1.200 ... 13.80 The first analysis was made by Langlois, whose investigations of the sub- ject of the action of steam on heated charcoal are also quoted by Dr. Percy (pp. 364, 365). These investigations showed that the gas obtained when the charcoal was red hot contained about 22 per cent, of carbonic oxide, and about 18 per cent, of carbonic acid, but that when the "charcoal was kept at a red-white heat the proportion of carbonic oxide rose to 42 per cent, and that of carbonic acid fell to 6 per cent. The second analysis was made by Frankland. The apparatus patented some years ago by Mr. Joshua Kidd, produced gas which, as analysed by Mr. T. W. Keates, consulting chemist to the Metropolitan Board of Works, gave the following results ; — Carbonic oxiile . 28.6 pei' cent. Hydrogen . . . 14.6 ,, Nitrogen . . . . 53.0 „ Carbonic acid .... . 4.0 „ The nitrogen in this gas is of course due to the air which is forced into the fuel along with the steam. The best quality of water gas obtained in practice seems to have been that produced by the Strong water gas apparatus, p. 261. The following is an analysis of the dry gas, afte'r having been washed, made by Dr. G. E. JMoore, of Jersey City, for the American Gas Fuel and Light Co., New York, who owned the patents for the Lowe and the Strong apparatus : — ' STRONG GAS COMPOSITION BY VOLUME. Oxygen Carbonic acid Nitrogen . Carbonic oxide Hydrogen . Marsh gas. C.77 per cent. 2.05 „ 4-43 , ,1 35-88 „ 52.76 ., 4-II „ 100.00 The weight of a cubic foot of this gas at 62° F. is stated to be 0.041 16 lb and it requires for its combustion 2.47 cubic feet of air weighing 0.1880 lb. Dr. Moore states that the theoretical calorific intensity of the flame of this gas is over 5400° F., a temperature which of course could not be attained in practice, as it is beyond the point at which dissociation of the gases begins. These facts seem to indicate that there is still room for a producer which will combine the action of the distilling retorts with the manufacture of water gas from the resulting coke, and which will thus utilize the whole of the fuel for the manufacture of gas, without deteriorating its products by any admixture of atmospheric air or nitrogen. Such a producer has been proposed by F. J. Rowan, in a British patent. No. 2693 — 1885. 286 NATURAL GAS. WATtTBAL GAS AS FUEL. In Amei'ioa, since the year 1875, considerable quantities of combustible gas have been obtained from wells or bore-holes, originally drilled in searching for petroleum. It may be stated, generally, that gas has been found in nearly every oil-well drilled ; but all gas-wells do not yield petroleum. The use of this gas as fuel has grown to such importance that the area of territory con- taining gas-bearing strata is being carefully observed, and numerous bores have been drilled for gas, in order that it should be systematically used on an extended scale. According'to Mr. C. A. Ashburner ,* a well at Sheffield, Pennsylvania, was drilled in 1875, and in September 1885 was still supplying that town with light and fuel. Mr..Andrew Carnegiet records that in 1878 a company drilled for oil at Murraysville, about eighteen miles from Pittsburg, and at a depth of 1,320 feet struck an enormous reservoir of gas, which escaped with such force that the drills and derrick were thrown high into the air, and broken, the roar of the escaping gas being heard in Munroville, five miles distant. The same writer observes that "it is now [1885] many years since the pumping engines at oil-wells were first run by gas, obtained in small quantities from many of the holes which failed to yield oil. In several cases, immense gas-wells were found near the oil-district ; but some years elapsed before there occurred to any one the idea of piping it to the nearest manu- facturing establishments, which were those about Pittsburg." One of the ear- liest attempts to use the gas for manufacturing operations seems to have been about 1879, when Mr. John RogersonJ states that hesawit used in puddling furnaces at an ironworks outside Pittsburg — the gas having been brought, he was told, a distance of about fifteen miles. Thie does not seem to be the same instance as is referred to by Mr. Carnegie when he says (speaking in 1885) that " some years ago the product of several gas-wells in the Butler region were piped to two mills at Sharpsburg, five mUes from Pittsburg city, and there used as fuel, but not with such triumphant success as to attract much attention to the experiment. Failures of supply, faults in the tubing, and imperfect appliances for use at the mills combined to make the new fuel troublesome." The Murraysville gas at first escaped from the well through four pipes, each of 2 inches diameter, ignited, and allowed to go to waste by burning uselessly for five years, although the well was only nine miles from the steel rail mills at Pittsburg ; the reasons for this given by Mr. Carnegie being the cost of the pipe-lines, and also the fact that the business of conducting the gas to the mills, and of using it when it got there, was not understood untU more recent times. Mr. Carnegie thus describes the appearance of the burning gas, as observed by him at Murraysville and at the wells in Wash- ington County in the autumn of 1884 : — " In the Murraysville district, the gas rushes with such velocity through a 6-inch pipe, extending, perhaps, 20 feet above the surface, that it does not ignite within 6 feet of the mouth of the pipe. Looking up into the clear blue sky, you see before you a dancing golden fiend, without visible connection with the earth, swayed by the wind into fantastic shapes, and whirling in every direction. As the gas from the well strikes the centre of the flame and passes partly through it, the lower part of the mass curls inward, giving rise to the most beautiful efiects gathered into graceful folds at the bottom — a veritable pillar of fire. There is not a particle of smoke from it. The gas from the wells at Washington was allowed to escape through pipes which lay on the ground. Looking down from the roadside upon the first well we saw in the valley, there appeared • " Trans. Amer. Inst. Min. Eng.," vol. xiv. pp. 428-439. . t "Jour. Iron and Steel Inst," i. 1885, pp. 168-178. J Jbid. p. 182. NATUEAL GAS. 287 to be an immense circus ring, the verdure having been burnt and the earth baked by the flame. The ring was quite round, as the wind had driven the flame in one direction after another ; and the efiect of the great golden flame lying prone upon the earth, swaying and swirling with the wind in every direction, was most startling." In the early part of 1885, it was stated that eleven lines of pipe then conveyed gas from the various wells to the manufacturing establishments in and around Pittsburg, the largest of these pipes being, for the latter part of the distance, 1 2 inches in diameter. Some were of 8 inches throughout, while the lines originally laid were 6 inches in diameter. The cost of laying pipe-lines fell in 1885 to about _;^i,5oo per mile, from about double that amount, which was the cost six to eight years previously, so that the cost of a line to Pittsburg might be said to be ^^27,000 ; the cost of drUhng being about ^1000. In 1883, a gas company offered to supply Messrs. Carnegie Brothers with gas for a sum per annum equal to their coal bill (their coal at that time cost three shillings a ton) until the capital outlay for piping was reached, when the gas was to be supplied at half the cost of the coal. It took eighteen months to recoup the gas company, and the success of the introduction of this fuel in this instance induced the starting of other pipe- lines for gas, and the leading of them into the city of Pittsburg, which is 15 to 18 miles from, the wells. In a Paper read at the Pittsburg meeting of the American Institute of Mining Engineers, Mr. W. P. Shinn stated that, according to the report of one of the companies supplying the city of Pittsburg, the supply of gas was drawn from 42 wells, situated in the Mur- raysville, Tarentum, and Washington fields, about 20 to 22 miles from the Post Office. The mains and distribution pipes then laid were 1,773,662 feet, or 335 miles 4,862 feet, in length. The amount of coal displaced by this company's gas was about 10,000 tons per day. Mr. H. M. Chance* estimated that the total amount of coal displaced daily by gas about the end of 1885 was 10,000 to 15,000 tons; whilst Mr. C. A. Ashburnerf states that, in the city of Pittsburg, 1,500 dwellings, 66 glass-works, 34 rolling-mills, and 45 other industrial establishments were in September 1 885 being supplied with natural gas, mainly for heating purposes ; the amount of coal displaced being esti- mated at 1 0,000 tons daily. The estimated value of the coal thus supplanted in Pennsylvania and the adjacent States, for three succeeding years, is given as follows : — In 1882 ;^43.ooo 1883 95.000 1884 .... ... 292,000 About two-thirds of the last amount (or ;^2 20,000) represents the consump- tion in the Pittsburg district. The extent of the territory which may be considered either as the reservoir or as containing the source of natural gas has not yet been clearly defined. One writer statesj that the district of natural gas covers a much greater area than that of oil. In general, it may be said to include a section of country extending from Western New York, through Pennsylvania into West Vir- ginia and Ohio, and lying nearly parallel to the Alleghany Mountains. The width of this section varies considerably — the boundary lines are very irregular, and are being extended by the finding of new wells. Although the outlines enclose a large territory, gas is found in only a small portion of it, and then in spots and narrow belts or lines. It was estimated that in 1885 there were 500 gas-wells in the oil country and its vicinity, which were producing at least 100,000,000 cubic feet per day. • " Iron Age," vol. xxxvii. Ko. 12. t " Tvans. Amer. Inst, of Min. Eng.," Sept. i885- J " Iron Age," vol. xxxv. No. 17. 288 NATURAL GAS. . The principal gas-producing districts are evidently those of Murraysville and of Washington County. Dealing with the districts surroundiag Pitts- burg as a centre, Mr. Carnegie says* that in the Murraysville field he found, in the autumn of 1884, that nine wells had been sunk, and were yielding gas in large quantities. " One of these was estimated as yielding 30,000,000 cubic feet in twenty-four hours. This district lies to the north-east of Pitts- burg, running southwards from it towards the Pennsylvania Railroad. Gas has been found upon a belt averaging about half a mile in width, for a distance of between four and iive miles." Thirty successful wells are now in operation in this district. " Beyond that, we reach a point where salt water flows into the wells and drowns the gas. Several wells have been bored upon this belt near the Pennsylvania Railroad, and have been found to be useless from this cause. Geologists say that in this region a depression of 600 feet occurs in the strata, but how far the fault extends has not yet been ascertained. Wells will, no doubt, be sunk southwards of the Pennsylvania Railroad, upon this- half-mile belt. Swinging round towards the south-west, and about twenty miles from the city, we reach the gas-fields of Washington County. There are now five wells yielding gas in that district, and others are being drilled. Passing still farther to the west we reach another gas territory, from which manufacturing works in Bever Falls and Rochester, some twenty-eight miles west of Pittsburg, receive their supply. Proceeding with the circle we are drawing in imagination around Pittsburg, we pass from the west to the north-west without finding gas in any considerable quantity, until we reach the Butler gas-field, equidistant from Pittsburg on the north-west with Wash- ington Co. wells on the south-west. Proceeding now from the Butler field to the AUeghany river, we reach the Tarentum district, stiU about twenty miles from Pittsburg, which is supplying a considerable portion of the gas used. Drawing thus a circle around Pittsburg with a radius of fifteen to twenty miles, we find four distinct gas-producing districts. In the city of Pittsburg itself, several wells have been bored ; but the fault before men- tioned seems to extend towards the centre of the circle, as salt water has rushed in and rendered these wells wholly unproductive, although gas was found in all of them." Since Mr. Carnegie recorded these observations, some very powerful gas wells have been found in Washington Co. It is saidf that the most powerful gas-well in the world is to be found there now. The rush of gas was origin- ally so great that it was almost beyond control, and there was a constant fear lest the tubing, &c., should be blown to pieces. It was consequently decided to sink another well within 100 feet of the first, in the hope that the gas- pressure would be thereby diminished. Instead of a 3-inch casing, the new well was lined with 6 -inch heavy iron pipe, which was carefully secured. At the end of less than sixty days from starting the new bore, the depth of the first — called the McGuigan — well was reached, this depth being 2,238 feet, and scarcely any gas was found. At the depth of 2,250 feet, however, the gas was struck, tools were blown out, and then the greatest flow of gas observed as yet in the Washington field took place. An efiect on the McGuigan well was immediately noticed ; its roar diminished and its pres- sure became weaker, ond it was finally screwed down; as a consequence of this operation, a larger quantity of gas issued from the new well. Dealing with the geological formations in which natural gas is found, Mr. C. A. Ashburner J gives the results of observations made in connection with the geological survey of Pennsylvania. The oil and gas regions of * " Jour. Iron and Steel Inst,," vol. ii. 1883. t " Iron Age," vol. xxxvii. No. 10 ; " Jour. Iron and Steel Inst.," vol. i. i886, p. 265. J "Trans. Amer. Inst. Min. Eng.," Sept. 1885. See "Miu. Proc. Inst. C.E.," vol. Ixxxiii. p. 491. NATUEAL GAS. 289 Pennsylvania are substantially one in a geological sense. The strata drilled through by the gas wells in the vicinity of Pittsburg are in a general way the same as those of the Beaver and other oil districts, lying at distances varying from eight to forty-five miles from that place. Gras is a common associate of liquid oils, and the product of the so-called dry gas wells, though supposed to be free from oil and water, generally yields one or both in small quantity when subjected to great compression. The rocks of the oil and gas regions lie neatly horizontally in broad and almost imperceptible folds, whose axes are, roughly speaking, parallel to the escarpment of the Alleghany moun- tains. The maximum dip is 69 feet per mile, but is generally much less. The vertical range of gas-producing beds is included in about 3,000 feet of carbon- iferous and Devonian strata, extending from the Mahoning sandstone at the base of the lower barren coal measures, 500 feet below the Pittsburg coal seam, down to the Smithport oil sand. There are three principal gas horizons, the first being probably the representative of the Venango first oil sand, 1,800 to 1,850 feet below the Pittsburg coal; the second, the Sheffield gas sand, corresponding with the lowest oil bed of the Warren district, 2,220 feet below the Mahoning sandstone; and the third, the Bradford oil sand, 1,775 ^^^^ below the Pottsville conglomerate. In the adjoining States of West Virginia, Ohio, and Kentucky, natural gases have been obtained from lower horizons down to the lower Silurian limestones ; but in the most productive wells the gas is derived from the Devonian sands. It is believed that the gas is not indigenous to the saud rocks producing it, but that it is derived from the decomposition of organic matter contained in the strata below. If this be so, the amount of gas contained in any one sand depends on the extent to which the rocks are cracked below it, to allow the gas from the lower fossUiferous level to flow upwards ; and the continuity of the covering strata, which, if mvch cracked above the gas sand, would allow it to escape into the atmosphere and disappear. The absence of both petroleum and natural gas in the plicated strata east of the oil regions is evident from the fact that these strata extend far beyond the areas in which oil and gas are found, and even within these areas the direction of certain productive flows is due to the jointing of the strata. Prof. E. Orton has examined the records and cores of six wells which were bored during 1884 in Hancock and Wood counties, Ohio. He reports* that they agree entirely in their main features. All begin in Upper Silurian limestone, and find their main supply of gas in the Trenton limestone. The Trenton limestone was drilled through in only one well. The gas obtained from these wells contained a notable quantity of sulphuretted hydrogen. In selecting localities for boring gas wells, the so-called " anticlinal theory " has been most generally followed. This supposes that the most abundant flow will be obtained on or near the summit of an anticlinal arch ; but this is not of universal application, because in many notable instances the gas has been found in synclinal troughs or in perfectly horizontal strata. On the other hand, some of the largest wells have been found on the crests of anticlinal axes, one of the most notable being the Sheffield well, drilled in 1875. This one is remarkable from the great pressure of the gas, which rendered the drilling difficult. A vein of salt water, passed through at 418 feet, was allowed to leak into the well ; the gas sand, 45 feet thick, was struck at 1,350 feet, when the gas, being suddenly relieved from pressure, as it expanded into the well absorbed heat from the water so rapidly as to form a core of ice about 200 feet deep, which nearly stopped up the bore. The average pressure of gas in the Pittsburg district is from 100 to 200 lbs. per square inch. At Carnegie Brothers' steel works, nine miles • " Science," vol. v. p. 474. 290 ANALYSES OF NATURAL GAS. from the well at Murraysville, it is 75 lbs. per square inch. The highest pressure recorded as measured is 750 lbs. per square inch. The average calorific value of natural gas is not yet fully determined, but some experiments have shown that about 1,000 cubic feet of the gas weighing about 38 lbs. Av., are equal in heating power to about 55 lbs. of Pittsburg bituminous coal, or about 20,000 cubic feet to the ton. As regards its chemical composition, the following is an analysis of the gas made by Dr. Q. Hay for the Natural Gas Commission, and published in the " Engineering and Mining Journal," vol. xxxix. p. 247 : — Per cent. Carbonic anhydride 0.00 Carbonic oxide ...... . i.oo Heavy hydrocarbons 0.50 Marsh gas 9S20 Hydrogen . . • . ... 2.00 Oxygen . . . . ... 1.30 Nitrogen 0.00 100.00 This, however, does not quite agree with the analyses given by Mr. S. A. Ford, chemist to the Edgar Thomson Steel "Works, who communicated the following examination of the gas, through Mr. Carnegie, to the Iron and Steel Institute : — " So much has been claimed for natural gas as regards the superiority of its heating properties as compared with coal, that some analyses of this gas, together with calculations showing the comparison between its heating power and that of coal, may be of interest. " These calculations are, of course, theoretical in both cases, and it must not be imagined that the total amount of heat either in a ton of coal or 1,000 cubic feet of natui'al gas can ever be fully utilized. In making these calculations, I employed as a basis what, in my estimation, was a gas of an average chemical composition, as I have found that gas from the same well varies continually in-its composition. Thus, samples of gas from the same well, but taken on different days, vary in nitrogen from 23 per cent, to nU, carbonic acid from 2 per cent, to nil, oxygen from 4 per cent, to 0.4 per cent., and so with all the component gases. " Before giving the theoretical heating power of 1,000 cubic feet of this gas, I will note a few analyses. The first four are of gas from the same well ; samples taken on the same day that they were analysed. The two last are from two different wells in the East Liberty district. I also give a few analyses of Siemens' producer gas. The immense heating-power of the natural gas over the Siemens' may be seen at a glance when compared bulk for bulk. Analyses of Natural Gas. No. I. 10/28/84 No. 2. No. 3. ^o. 4. No. 5. No. 6. When tested . 10/29/84 11/24/84 12/4/84 10/18/84 Nil 10/25/84 Carbonic acid . •8% •6% Nil •4°/o ■3o7o Carbonic oxide . I.O .8 ■S87. ■4 i.ooVo .60 Oxygen . I.I .8 .78 .8 2.10 1.20 defiant gas ■ 7 .8 .98 .6 .80 .60 Ethylio hydride 3-6 5-S 7.92 12.30 5.20 4.80 Marsh gas 72.18 65-25 60.70 49.58 57-85 75-16 Hydrogen 20.02 26.16 29.03 35-92 9.64 14-45 Nitrogen . Heat units Nil Nil Nil Nil 23.41 2.89 728,746 698,852 627,170 745.813 592,380 745.591 HEAT VALUE OF NATURAL GAS. 291 Analyses of Siemens' Producer Gas. {See vol. xi. p. 300, " Tromsactiona of American Institute of Mining Engineers.") Carbonic acid . Carbonic oxide . Marsli gas . Nitrogen . Heat units . 3-97o 273 1.4 67.4 8-67. 20.0 8.7 1.2 61.4 9.37o 16.5 8.6 2.7 62.9 i.57» 23.6 6.0 30 6S-9 6.i7o 22.3 28.7 1.0 41.9 93.966 97.184 99,074 1 14.939 164,164 .60 per cent. .60 " We will now show how the natural gas compares with coal, weight for weight, or in other words how many cubic feet of natural gas contains as many heat units as a given weight of coal — say a ton. " In order to accomplish this end, we will be obliged, as I have said before, to assume as a basis for our calculations what I consider a gas of an average chemical composition, viz. : — Carbonic acid .... . . Carbonic oxide . . .... Oxygen . . ... . .80 defiant gas ..... i .00 Ethylio hydride .... . . 5.00 Marsh gas ... .... 67.00 Hyilrogen 22.00 Nitrogen 3.00 "Now by the specific gravity of these gases we find that 100 litres of this gas will weigh 64.8585 grams, thus — Marsh gas ... . 67.0 litres weighs 48.0256 grams i-o .. 1-2534 „ Olefiant gas Ethylio hydride Hydrogen Nitrogen . Carbonic acid . Carbonic oxide . Oxygen . 5.0 22.0 3-0 .6 .6 .8 6.7200 1.9712 37632 1.2257 .7526 1. 1468 Total . . . 64.8585 " Then if we take the heat units of these gases we will find — Marsh gas . Olefiant gas Ethylio hydride Hydrogen . Carbonic oxide Nitrogen Carbonic acid Oxygen 48.0256 grams contains 627,358 heat units '•2534 ,, 14,910 6.7200 ,, 77,679 1. 9712 ,, 67,929 .7526 „ 1,808 37630 „ — 1.2257 „ _ 1. 1468 „ — 64.8585 „ 789,694 64.8585 grams are almost exactly 1,000 grains, and i cubic foot of this gas will weigh 267.9 grains, then the 100 litres or 64.8585 grams or 1,000 grains are 3.761 cubic feet. " 3.761 cubic feet of this gas contains 709,694 heat units, and 1,000 cubic feet will contain 210,069,604 heat units. "Now 1,000 cubic feet of this gas will weigh 265,887 grains, or in round numbers 38 lbs. avoirdupois. "We find that 64.8585 grams, or 1,000 grains of carbon, contain 524,046 heat units, and 265,887 grains, or 38 lbs. of carbon, contain 139.398,896 heat units. Then 57.25 lbs. of carbon contain the same number of heat units as a 1,000 cubic feet of the natural gas — viz., 210,069,604. " Now, if we say that coke contains in round numbers 90 per cent, carbon, u 2 292. HEAT VALUE OF NATURAL GAS. then we will have 62.97 lbs. of coke equal in heat units to 1,000 cubic feet of natural gas. " Then if a ton of coke, or 2,000 lbs., cost los., 62.97 lbs. will cost 4 pence or 1,000 cubic feet of gas is worth 4 pence for its heating power. " We will now compare the heating power of this gas with bituminous coal, taking as a basis a coal slightly above the general average of the Pitts- burg coal, viz. : — Carbon . 82.75 per cent. Hydrogen . 5.31 Nitrogen .... 1.04 Oxygen 4.64 Ash . 5.31 Sulphur .95 "We find that 38 lbs. of this coal contains 146,903,820 heat units. Then 54.4 lbs. of this coal contains 210,069,640 heat units, or 54.4 lbs. of coal is equal in its heating power to 1,000 cubic feet of natural gas. If our coal cost us 5s. per ton of 2,000 lbs., then 54.4 lbs. will cost 1.632 pence, and 1,000 cubic feet of gas Will be worth for its heat units 1.632 pence. " As the price of coal increases or decreases, the value of the gas will naturally vary in like proportions. Thus, with the price of coal at los. per ton, the gas will be worth 3.264 pence per 1,000 cubic feet. " If 54.4 lbs. of coal be equal to 1,000 cubic feet of gas, then one ton, or 2,000 lbs., will be equal to 36,764 cubic feet, or 2,240 lbs. of coal will be equal to 40,768 cubic feet of natural gas. " If we compare this gas with anthracite coal, we find that 1,000 cubic feet of gas is equal to 58.4 lbs. of this coal, and 2,000 lbs. of coal is equal to 34,246 cubic feet of natural gas. Then if this coal cost 26*. per ton, 1,000 cubic feet of natural gas will be worth 9^ pence for its heating power. " In collecting samples of this gas I have noted some very interesting deposits from the wells. Thus, in one well the pipe was nearly tilled up with a soft greyish-white material, which proved on testing to be chloride of calcium. In another well, soon after the gas vein had been struck, crystals of carbonate of ammonia were thrown out, and upon testing the gas I found a considerable amount of that alkali, and with this well no chloride of calcium was observed until about two months after the gas had been struck. " In these calculations of the heating power of gas and coal, no account is of course taken of the loss of heat by radiation, &c. My object has been to compare these two fuels merely as regards their actual value in heat units." A practical test* of the fuel value of natural gas has been carried out by the Westinghouse Air-brake Company, who possess valuable gas wells at Pittsburg. Taking the usual " best " quality of Pittsburg coal, it was found that its evaporating duty in a particular boiler was 10.38 lbs. of water per lb. of the solid fuel. With the same boiler 1.18 cubic feet of natural gas evaporated i lb. of water ; whence it follows that i lb. of coal is equivalent to 12.25 cubic feet of gas, or that 1,000 cubic feet of the gas were as good as 8i|f lbs. of coal. According to calorimetric tests, 55.4 lbs. of coal contain the same number of heat units as 1,000 cubic feet of gas, so that the practical test was better for the gas than might have been expected. Even with this good result, however, as the coal in question is worth only about five shillings per ton, or ^d. per cwt., the fuel value of the natural gas supply used in competition with it can only be about 2d. per 1,000 cubic feet. It is evident that the expenses of winning, piping, and managing a natural gas supply in the neighbourhood of Pittsburg must be very low to pay a profit upor a service sold upon this valuation. It is stated, however, that there is a greater economy in the use of natural gas, as compared with coal, • See " Mechanical World," Dec. 17, 1886 ; " Jour. Iron and Steel lust.," vol. i. 1887, PP> 366, 418. LIQUID FUEL. 293 for domestic purposes and small industrial establishments, which is inde- pendent of its advantages when used for purposes for which freedom from smoke is a recommendation. The freedom of the gas from sulphur has been an important element in its metallurgical value. At first, on account of its abundance, natural gas was burned without regard to waste, but economical appliances are being introduced. Messrs. Carnegie Bros, have attached to each puddling furnace a small regenerative appliance, which is found to be effectual in saving gas. The principle of the argand burner has also been applied to the burning of this gas by Mr. E. J . Dashbach,* with the result that furnaces to which it has been applied work with greater speed. It is saidf that, when this gas is used in ordinary open -hearth furnaces, it is liable, on being heated, to decompose, with the formation of a very pure, hard, and glossy coke, which chokes up the chequer work of the regenerators. LIQUID FtTEL. The discovery of large quantities of petroleum in America, and the accumulation of dead oil in this country (owing to the temporary abandon- ment of the creasoting process), drew attention to the employment of these substances as liquid fuels. An American Commission appointed to investigate the question of the employment of petroleum as fuel reported that it was more than twice as effective as anthracite for steam raising, and methods were soon proposed for the use of liquid fuel, principally for steam raising. The following table (from " Facts about Oil," by Mr. John P. Zane) shows the number of producing wells, the amount of production, the price of oil per barrel at the wells, consumption and stock on hand in America for the last twenty-eight years : — Tear. No. of VNells. Amount of Pro- ductioB. Average Price for the Year. Consumption. stock. 1859 I 2,000 I20.OO i860 2CX3 200,000 9 60 1861 200 2,110,000 2.73 1862 400 3,055,000 1.06 'l^J 500 2,610,000 3- IS 1S64 1,000 2,130,000 9874 1865 1,000 2,721,000 6.59 1866 900 3,732,000 374 1867 900 3,583,000 2.41 1868 1,000 3,716,000 3-62J 1869 1,000 4,351,000 5-631 1870 1,044 5.371.000 3.89 5.156,528 534.626 1871 I.47Z 5,531,000 4-34 s.553,626 532,000 1872 1,201 6,357,000 3-64 5.804,577 1,084,423 1873 2,361 9,932,000 1.83 9,391,226 1.625,157 1874 1.350 10,883,000 1.17 8.802,513 3.705,639 187s 2,38s 8,800,000 I-3S 8,956.439 3,550,200 .876 2,960 9,015,000 2.56! 9.740.461 2,824,730 'In 3.954 13,043,000 2.42 12,739.902 3.127,827 1878 3.018 15,367,000 1.19 13.879.538 4.615.299 'f?9 2,889 19,827,000 8Si 15.961,809 8,470,190 1880 4,194 26,048,000 944 15.590,040 18.938.430 1881 3.848 27,238,000 851 29,146,726 25,019,704 1882 3,269 30,460,000 78J 21,883,098 34,596,612 1883 2,886 24,300,000 i.05i 22,006,612 36,800,000 1884 2.309 23,500,000 U^ 23,500,000 36,800,000 1885 2,857 20,900,000 88 23,900,000 33,800,000 1886 3.52s 26,150,000 7ii 26,700,000 33,000,000 • " Engineering and Mining Journal," vol. xli. p. 90. t " Iron Age," vol. xxxv. No. 17. 294 . LIQUID FUEL. Admiral Selwyn * very early recognized the advantages possessed by a fuel in this concentrated and easily handled form, especially for use in steam ships and ships of war, and has repeatedly advocated its employment. Professor Rankinet also wrote on this subject, and he and Dr. B. H. Paul J investigated the theoretical efficiency of liquid fuels, calculating the evapora- tive power of the hydrocarbons as the sum of that of the hydrogen and carbon in each, as found by ordinary chemical analysis. It is to be observed, however, that the theoretical efficiency, as thus calculated, is not always to be depended on. When hydrocarbons are formed, there is a loss of energy in the act of formation, and the law of this loss has not yet been accurately ascertained. Moreover, numerous hydrocarbons exist whose properties are different, although their composition is the same, and these different hydrocarbons give out different amounts of heat on combustion, which amounts do not (as in the case of other hydrocarbons also) always agree with the calorific power, calculated as the sum of that of their elements. Thus, whilst marsh gas yields by experiment 2,672 units per lb. less than that due by calcula- tion from its elements, both olefines and acetylene yield a much larger amount of heat than is estimated from their chemical constituents. Kankine adopted as his unit the weight of coihbustible required to eva- porate I lb. of water at 212° F., under an atmospheric pressure of 14.7 lbs. per square inch. This is equal to 966 British thermal units (or 537 IVench or centigrade units), or 966 times the quantity of heat that raises i lb. of water from 39° to 40° F. His observations were reduced as follows : — Let E be the corrected and reduced evaporation, £ the weight of water actually evaporated, Tj the standard boiling point (say 212° F.), Tf the temperature of the feed water, Tb the actual boiling point observed ; then f T.-T,-Ho.3(T,-TJ ) ^ - M ' ^ 966 F. or 537 C. / • The result shows the number of times its own weight of water which a fuel would evaporate at the standard temperature if there were absolutely no waste of heating power, but, as there is always more or less waste, the „ . „ . . , , , . E' (available) , . , efficiency of a furnace is expressed by the ratio — p, /. . .> — , which, were there no loss, would be = i. To ascertain the loss of units of evaporation by the waste gases, Rankine proposed the formula : — 1 + A/' Loss by chimney = To (F.°), where i -(- A' denotes the weight of burnt gas per unit weight of fuel, and Tc (F.°) the temperature of chimney gases above that of the atmosphere. For ordinary coal' i -t- A' ranges from 13 to 25 (19 being a medium quantity), and for hydrocarbon oils it is 16.3, if no excess of air is necessary above what is required for the oxidation of the fuel. Taking coal examples with chimney draught (600° F. being the tem- perature of waste gases necessary to produce draught), where I -H A' = 13 ' ... 19 ... 25^ Tc . . . . = 600° ... 600° ... 600° Volume of gases in cubic feet . =325 ••• 475 ■•• 625 Loss of evaporative power . = 1.95 ... 2.85 ... 3-75 • "Min. Proo. Inst. C.E.," toI. xxix. p. 194; "Jour. Eoyal United Service Institution," 1865, vol. ix. p. 66 i "Trans. Inst. Naval Architects," 1868, 1869, 1870, 1885. f "Jour. Boy. U.S. Inst,," vol. xi. p. 218. t "Jour, of the Society of Arts," April 17, 1868. LIQUID FUEL, 295 The theoretical evaporative power of hydrogen and carbon (under various conditions) is given by Rankine as follows : — Weight. Air per Unit of Weight. Units Evaporated. Hydrogen . .... Carbon, solid Carbon, solid, half oxidized . Carbon gas in 2^ parts carbonic oxide . Carbon, gaseous (calculated) . 8 2S 36 12 6 6 12 64.2 150 4-5 10. s 21.0 The figures for carbon apply to charcoal carbon. Rankine also assumed, in his calculation, that six units became latent in the operation of making gaseous from solid carbon. Dr. Paul calculated the evaporative power of the hydrocarbons as the sum of that of the hydrogen and carbon supposed to exist in each, on the assumption that, when burned with the minimum- of air for perfect com- bustion, each lb. of carbon will evaporate 11.359 l^s., and each pound of hydrogen 41.895 lbs. of water at 60° F. into steam at 212° F. His results are contained in the following table. Column V. gives the evaporative duty when the furnace gases are discharged at 600° F. above the temperature of the air supplied to the furnace. I. Carbon. II. Hydrogen. III. Oxygen. IV. Evaporative Power: IbB. Water at 212° F. V. Evaporative Duty : lbs. Water at 60° F. Phenol . 76.60 6.40 17.00 12.2437 10.5025 Cresol . 77.70 741 14.82 13.0096 1 1. 1632 Naphthalin 9S-7S 6.2s — 15-4350 13.0751 Anthracene 94.38 S.62. — 15.2417 13.2675 Xylol . . 90.56 9-44 — 16.5866 14.2415 Cumol 90.00 10.00 — 16.7838 14.4126 Cymol . 89-55 10.45 — 16.9422 14.5500 In estimating the theoretical evaporative efficiency of different com- bustibles from their chemical constitution, Eankine proposed the formula, E= 15C-1- 64H -80, but pointed out that it gives a slightly higher value for evaporative power than experiment showed. To calculate the amount of air necessary for the combustion of any fuel, he used the rule A=i2C + 36H-4iO. The quantity actually used, is, however, generally much in excess of that found by this rule. Rankine announced the following results obtained by the use of these rules : — Description of Fuels, Chemical Composition. A. E. Evaporation due to | C. -93 H. 0. C. 8 Charcoal II. 5 14.0 14.0 Coke .... .88 10.6 13.2 13.2 Eock oils 1 S>»1«' .84 .16 15-75 22.7 12.7 10. •S5 ■IS 1565 22.5 12.66 9.84 Coal . .87 .05 .04 12. 1 15-9 13-05 2.85 1, .85 .05 .06 II. 7 15-5 12.75 2.75 T, ',' , ■ ■75 .05 .05 10.6 14. 1 11.25 2.85 Kthylene, C„H Acetylene, C.H, . •75 .25 18.0 27-3 11.25 16.05 ■85 .14 15-43 22.1 12.9 92 Peat, dry . .56 .06 ■31 7-7 10.0 8-5 1-5 Wood, dry . .58 •05 .40 6.0 7.5 7-5 296 LIQUID FUEL. Paul arrives at the effective heat as follows : — COMBUSTION OF I LB. OF OAEBON. Heat Units. Equivalent Evaporation of Water. At 212° P. At 60° P. Total heat of combustion .... Available hefat Waste of furnace gases at 600° F. Eifective heat .... 14,500 14,500 3,480 15 3-6 11,020 1 1.4 9.8 COMBUSTION OF I LB. OF HYDEOGEN. Total heat of combustion .... Latent heat of water vapour Available heat Waste heat of furnace gases Effective heat . 62,032 8,695 64.2 11.9 53,337 11,520 41,817 43-3 38. The following is the calculation per lb. for two typical hydrocarbons having the composition indicated : — A. Carbon. Hydrogen. Total Heat of Equivalent Evaporation of Water. At 212°. At 60°. .86 X 14,500 = 12,470 .14 X 62,032 = 8,684 21,154 21.9 18.8 Furnace Graaes. Heat Units in Furnace Gases. 2.2 lbs. Carbonic acid . . . 3.16 Water vapour . . i .26 Nitrogen. . 11.45 Surplus air . . 14-37 30-74 411 i,i! 2,124 4-577 4.8 Total beat of combustion Latent heat of water vapour 21,154 1,217 1.3 ♦ 4.8 15.8 13-6 Available heat Waste in furnace gases Effective heat . - 19,937 • 4,577 • 15,360 Theoretical evaporating power 21.9 Relative efficiency, taking carbon as i, = 1.39. LIQUID FUEL. B. 297 Carbon. Hydrogen. Total Heat of Equivalent Evaporation of Water. At 212°. At 60". ■75 X H.500 = IO,77S .25 X 62,032 = 15,508 26,283 27.1 23.1 Furnace Gaaes. Heat Units in Furnace Gases. 2,6 lbs. Carbonic acid .... 2.75 Water vapour . . 2.25 Nitrogen 13.39 Surplus air . . 17.39 3578 641 1,968 2.483 5.450 Total heat of combustion . . 26,283 Latent heat of water vapour . 2,174 Available heat . . 24,109 Waste in furnace gases . . . 5,450 Effective heat .... 18,659 Theoretical evaporating power 2.2 5.6 193 16,6 27.1 1 Relative efficiency, taking carbon as 1, = 1.69. Paul estimates that, on the whole, i lb. of hydrocarbon fuel is not likely in practice, and on the average, to evaporate more than 16 lbs. of steam; but, if only just sufficient air for combustion were supplied (i.e., half the quantities estimated for above), the effect might in case A. be increased by 13 or 14 per cent. On the latter understanding, also, Paul takes dead oil as on an average capable of evaporating 13 lbs. of water from 60° F. to steam at 212 P. Storer has estimated the theoretical evaporative power of a pure petroleum containing 86 per cent, of carbon at rather more than 18 lbs. He also states that a kilo, of crude petroleum evaporates 10.36 kilos, of water against 5.1 kUos. evaporated by the same weight of anthracite. The following figures are due (1866-9) *'° Seville : — Heavy oil from West Virginia Light „ „ ,, Pennsylvania Heavy ,, Ohio . Oil from Java (Rembaug) . ,, „ (Cheribon) . Petroleum from Schwabwiler (Alsace) „ ,, E. Galicia W » it^ ' • }i ' Crude shale oil from Autun (France) . , Heat Units. 10,180 10,223 9,963 10,399 10,831 9,593 10,183 10,458 10,005 10,235 9,95° As the above oils vary considerably in their composition — the Galician oils more particularly — these results can have but a general value. As regards suitability for liquid fuel, it is to be observed that most tars and petroleum admit of combustion in suitable plant ; but those liquid fuels are least valuable which contain most oxygen and nitrogen. Sulphur, 298 RUSSIAN PETROLEUM. ■which is, of course, an objectionable constituent, always occurs in coal tars' but is frequently absent from petroleum and petroleum residues. The rapid development, since the year 1876, of the enormous stores of petroleum existing at Biku and the Caucasus district, and the consequent vast accumulations of naphtha refuse there as the result of refining the natural oil, have led to a greatly extended employment of liquid fuel in South-east Europe— princip illy in South-east Russia. Some idea of the extent of this oil-producing region may be derived from the following figures : — " In the beginning of the present century, the estimated yield from the springs at Baku was about 4,009 tons annually, and of that quantity the larger portion went to Persia. From 1813 to 1872, the raising of the oil was made a State monopoly, and production did not develop to any extent. Still, from 1832 to 1850 the average yearly output was 1,000,000 gallons, and in the next ten years the rate was increased to 2,000,000 gallons. By 1872, the production had grown to 7,679,905 gallons. At this time the product of the American oil fields began to flood, not only Europe, but B.ussia, and the Russian Government, becoming alive to the importance of the Baku district, abolished the monopoly." * By the end of 1873, the output had risen to 19,757,857 gallons, by 1874 to 24,313,215 gallons, and by the close of 1875 to 29,045,215 gallons. The output since 1875 ^^^ been as follows: — 1876 . 1,400,000 barrels or 56,000,000 1877 . . 2,000,000 » 80,000,000 1878 . 2,500,000 M 100,000,000 1879 • 3,000,000 ,, 120,000,000 r88o . to 1881 . 4,000,000 1} 160,000,000 1882 . 5,000,000 H 200,000,000 An area of about 4^ squar^ miles forms , the nucleus of the oil-bearing region of the Caucasus. The naphtha-bearing beds consist of sand, calcare- ous clays, marls, and, in places, compact sandstone, often of great thickness, and penetrated by bands of pyrites. As in Pennsylvania, the naphtha is in some places associated with salt water, which gives much trouble in driving bore holes. The plateau is on a level of about 140 feet above the surface of the Caspian, and a depth of 700 feet below that great lake has been reached by boring. Petroleum, however, is found not at Baku only, but, according to Mr. C. Marvin, it exists throughout the whole extent of the Caucasus, under the Caspian to Tcheleken, and again in the Little and Big Balkans beyond, a distance of over 1,200 miles. Professor RomanofFsky has proposed a method of boring for this oil which avoids the outcrops and the anticlinal bends of the oil-bearing strata, and arranges the bore holes to «trike the beds at not less than 400 feet below the outcrop. When the oil is struck, the pressure of gas, which occurs here as in America, forces the oil up, forming fountains of varying size. The gas pressure has been found to range between 50 lbs. and 300 lbs. per square inch, and, under the higher pressures, stones, clay, and sand are often projected out of the bore holes along with the oil, which breaks up into fine spray and is often carried far by the wind. In the year 1883 two fountains played simultaneously to a height of between 250 and 350 feet, and during 1887 one has, it is said, reached a height of 400 feet. Mr. Thomas Urquhartt observes that cases occur almost annually of petroleum gushing forth from wells under great pressure and spouting to a height of from 50 to 75 feet, with a diameter at the issuing point of from 10 to 15 • Mr. C. Marvin, "Baku, the Petrolia of Europe." t On the Useot Petroleum Refuse as Fuel in Locomotives, " Proo Inst M.E.," 1884, p. 272, SOURCES OF SUPPLY OF LIQUID FUEL. 299 inches. Such a fountain flows uncontrollably for weeks together, flooding all the immediate vicinity and forming lakes of petroleum. This oil is called " lake petroleum," and it loses, after a few days' settling, the more volatile portion of its constituents by evaporation. Vast quantities of oil have been lost from the breaking forth of foun- tains before any reservoirs had been constructed. Some of the fountains are intermittent, playing for from two to three hours at a time, and then ceasing for a day or two. These are the most lucrative, as they give time for storing their produce. Continuous fountains after a time become inter- mittent, finally subsiding into ordinary wells. A continuous fountain may yield over 3,300 tuns of oU, and require the labour of one hundred men to coil6ct and store its product. The daily yield is worth about ;£ioo, the cost of labour being from ;^i5 to £^20. At Balaxna (Black Town), near Baku, there are many large distilling establishments for manufacturing kerosene, benzene, photogen, &c., from crude petroleum. The bye-products or refuse are used for the manufacture of lubricating oils, but more generally as fuel. In Russia, the quantity of refuse in proportion to the distilled kerosene is very great; the finest kerosene amounts to about 25 per cent, only of the original weight of crude oil used, and ordinary commercial kerosene to only about 30 per cent., the remaining 70 or 75 per cent, being available for fuel. In America the results obtained from native petroleum are different, the amount of ordinary kerosene for illuminating purposes produced from the Pennsylvania crude oil being from 70 to 75 per cent, of the crude oil used. There is, however, very little difierence in the percentage composition of the crude oils of the two countries, as the following statement, due to M. Goulis- hambaroff',* shows : — Sp. Gr. Composition. Heating Power. British Units. Theoretical Evaporation per lb. at 8 Atmospheres. lbs. Carbon. Hydrogen. Oxjgen. Edsbian crade 1 Light petroleum oil J Heavy Russian naplitlia refuse Pehnstlvaniah crude heavy petroleum oil .884 ■938 .928 .886 86.3 86.6 87.1 84.9 '3-6 12-3 11.7 137 .1 I.I 1.2 1.4 22,628 19,440 19,260 19,210 17.4 16.4 16.2 16.2 Whilst America and Russia are at present the chief oil-producing coun- tries in the world, there are evidences that stores of natural petroleum are widely distributed over the globe. Oil has been already found in Roumania, Hanover, Burmah, Australia, Galicia, Egypt, India, New Zealand, Cali- fornia, and Africa, and will probably be discovered in other countries also. Natural bitumen exists in the West Indie^. The question of supply has a most important bearing on the use of liquid fuel, as it is only the existence of abundance of this fuel which can regulate the price of it to a point at which it can be used with advantage instead of coal. In addition to the products from natural petroleum, the visible sources of supply are — (i) the tar from gasworks ; (2) that which is recovered from coal used in blast-furnaces, coke-ovens, and gas-producers ; and (3) products from the mineral-oil industry. The first of these is not capable of much extension, at least in this country, but the second may be increased, as it is only quite recently that much attention has been directed to the recovery of bye-products from the use of coal in manufacturing operations. The mineral oil industry has been largely developed in Scotland during recent years, * Campt. Rend., tome Ixix. pp. 442-453. 300 METHODS OF USING LIQUID FUEL. the amount of shale distilled having been, in 187 1, 800,000 tons, producing 25,000,000 gallons of crude oil, whUst in 1885, 2,090,000 tons of shale were distilled, producing 62,712,000 gallons of crude oil. In connection with this method of obtaining oil. Admiral Selwyn has mentioned that in several parts of England — particularly on the southern coasts — there is a practically unlimited supply of shale, known as " Kimmeridge clay," which is said to yield 40 gallons of crude oil per ton. These combined sources of supply make it appear that there is less fear now than formerly that the demand can exceed the supply of liquid fuel. Its general introduction therefore depends principally on the price which can be paid for it without counter- balancing its advantages over coal. On this point there is much diversity of opinion, founded upon the view which is taken of its comparative advan- tages and upon the results obtained in trials of long or short duration. The solution of the matter largely depends on the evaporative or heat-producing effect which is realized by the use of this fuel ; but even with a small margin of economy in respect of that effect, there are special circumstances connected with the use of fuel in steamships, and especially in ships of war, which cause the other qualities of liquid fuel to weigh heavily in its favour. Methods of tTsing Liquid Fuel. — The various methods of using liquid fuel which had been introduced prior to the year 1878 were classified by the late Harrison Aydon ("Min. Proc. Inst. C.E.," vol. lii. p. 177, &c.*). 1. Injection with compressed air. — In this plan (patented by W. Bridges Adams in 1863) the oil was injected through a double nozzle from a tank by means of compressed air, a layer of incandescent coke being kept on the furnace bars. This is evidently the forerunner of the method introduced by Mr. Tarbutt in 1885. 2. Percolation through a porous bed. — The liquid fuel accompanied by heated air percolates upwards through a porous bed placed in the bottom of the furnace space. This system was introduced by C. J. Richardson in 1864, and improved in 1866 by the introduction of steam with the air supply. In Weir and'G-ray's modification of this plan, a porous bed was placed at the level of the fire-bars, the oil coming in through a perforated pipe at its lower surface; and a jet of steam, carrying in air along with it, was introduced above the furnace door. Aydon places St. Clair DevUle's plan as used in French locomotives in this class, although it differs from Richardson's to some extent. The oil was allowed by Deville to trickle through numerous small channels on to the upper surface of heated fire- bricks placed in the bottom of the ash-pit of the furnace, air being admitted through a small damper at the same level. 3. Vaporization. — The oil is fed into a small retort lying in, and heated by, the furnace ; the gas which is thus formed issues through numerous openings in jets, which are ignited. This plan was introduced in America by Col. Foote in the United States gunboat Palos, and is shown in Fig. 183 (p. 301), and a similar plan was patented (in 1865 and i867)bySirom and Barff, of Glasgow. In Col. Foote's plan, the retort was placed at the fire-bridge; small pipes, carrying 125 jets or burners, were led from the retort along the lines of the fire-bars ; and steam was admitted into the furnace, superheated in a zigzag coil placed over the gas jets. 4. Steam-spray injection. — A jet of steam, superheated if possible, is used to inject the liquid fuel into the furnace, at the same time breaking it up into the finest spray, turning it either wholly or partially into vapour, by the heat of the steam (and partly by the radiated heat of the furnace), and mixing it with the air supply, which is drawn in as an induced current. <» See also 0. C. D. Eoss, vol. xl. pp. 150-161 ; vol. xlii. p. 336. METHODS OF USING LIQUID FUEL. 301 This, in some form, has been the most successful, as it is the most con- venient, method of applying oil-fuel. It has been combined with a variety of arrangements in the combustion chamber — as, for instance, a layer of incandescent fuel covering the fire-bars ; a portion of the fire-bars covered with fire-bricks and the rest with fuel ; a combustion chamber entirely of fire-brick, all fire-bars being removed. The late Harrison Aydon was the first to introduce a practicable method of this class, which he patented with Messrs. Wise and Field in 1865-1867. Fro. 183. Colonel Foote's American Furnace, as tried in U.S. gunboat Falos. James Donald, of Glasgow, patented in 1868 a modification of the same plan, and another form was in 1874 applied by Urquhart to locomotives in Russia. Many varieties of injectors and nozzles have been subsequently introduced, but the successful use of oil on this system depends to a large extent on the proper distribution of brickwork in the combustion chamber so that what is required is a combination of the best nozzle with the best construction of furnace. 5. Vaporization in a separate (external) boiler or retort. — Here the retort is not heated in the furnace, and the'oil is vaporized by independent heating of the retort, or by the heat of steam passed into contact with the oil, or by a combination of both methods. The first was Dorsett's plan, patented in 1 863 and 1869; the second, a modification patented in America by Dr. C. J. Eames in 1875. Eames's generator was of wrought iron, similar to an egg-shaped boiler placed on end. It was divided by horizontal iron shelves, projecting alter- nately from each side, nearly across the generator. The generator was placed over a fireplace in which a coil of pipes was arranged as a superheater for the steam, which, after passing through the coil, entered the generator at the bottom. The oil was admitted by a pipe at the top, and, running on to 302 METHODS OF USING LIQUID FUEL. the top shelf, trickled across it and dropped to the shelf below, repeating this until the other shelves were passed in succession. A large surface of oil was thus exposed to the action of the superheated steam, which, entering below, passed upwards through the generator. The effect of contact between the steam and oil at the high temperature employed was that they mutually decomposed each other, and issued as gas at the top of the generator through pipes with regulating valves, from which the gas passed to a combustion chamber. Air for combustion was admitted here, and the flame then entered the furnace. Fig. 184 shows this arrangement of Eames' as applied to an iron-heating furnace with a steam boUer above, which was heated by the waste heat. Fig. 184. Fia. 185. f eAlieS' AMSKICAII ni|IIAee.(OOIISETTls SYSTEM MtSOVEB.) ' The manufacture of gas from oil* has received much attention in recent years, although chiefly in connection with its application to lighting. The production and quaUty of this gas are, however, of great interest in connec- tion with the use of liquid fuel, and, it is probable, will influence the methods of using oil to a large extent. In the apparatus used by Pintsch, Keith, and others, oil is simply dropped into a red-hot retort and volatilized in this way, from about 80 to 150 cubic feet of purified gas per gallon of oil being ob- tained, according to the quality of oil and the temperature employed. In a form of appai-atus made by Messrs. Rogers, of Watford, the oil is injeoted as spray into the red-hot retort by means of a steam jet, and from no to 120 cubic feet (after condensation and purification) of a very rich gas are obtained per gallon of oil. Fig. 185 illustrates an apparatus patented by Mr. J. B. Archer, of Washington, America, for the production of oil gas for furnaces. According to Archer's method of production, steam superheated to about 1000° F. is made to pass through an injector and draw with it a quantity of oil, which becomes mixed with the steam. The mixture is further heated to about 1300° F. when it receives an additional qu.antity of oil, and finally this mixture is heated to about 2400° F., whereby it is * H. E. Armstrong, "Jour. Soo. Chem. Indus.," vol. iii. p. 462; "A Manual of the Manu- facture of Gas from Tar Oil and other Liquid Hydrocarbons," by W. Burns, C.E. (London ; Spon) ; " A Manuelette of Destructive Distillation," by E. J. Mills, D.Sc, F.B.S. aydon's injectors for liquid fuel. 303 converted into permanent gas. The apparatus coroprises three concentric cylindrical casings, of which the outermost is enclosed in brickwork T, and consists of a superheater Q, having within it a helical passage y and a retort m, in which the gaseous mixture undergoes its final heating. Separated by an annular flue space z is the second casing v, of metal, formed_ with a helical . passage I, containing a helical pipe h of smaller diameter. In the flue space D is suspended the primary retort o, consist- ing of a vertical cylinder closed at its bottom s, which is diiectly heated by a circle of gas-jets B. The hot gases from these jets ascend through D, descend by z, and pass by the flue z' to the chimney. Within the en- larged part of the primary retort o is a spherical shell P, divided by per- forated partitions b, from which a helical pipe w extends down nearly to the bottom of the primary retort, where it terminates with an open mouth. Steam supplied by a pipe a enters the lowest coil of the superheater y, and flowing upwards by a pipe Y^ through the injector y'', to which the oil-supply pipe R is connected, draws in the oil, which passes with the steam, through the pipe r^ into the spherical shell p. Here the oil and steam are thoroughly mixed, and the mixture passes down the helical pipe w, up the body of the retort, and out at the top by a pipe E to the external mixing chamber Ei, where an additional quantity of oil is supplied to it by a branch e'' from the oil pipe r. From the mixing chamber e", the mixed fluid enters the inner pipe h of the hehcal retort v, flows along its convolutions, out at its lower open end, back along the convolutions of the helical passage i contain- ing the pipe, thence by the pipe u into the final retort M, whence it passes away by the pipe F as a permanent gas. By the pipe L gas can be led off without passing through the retort M, and the pipe l' of the burner B can be supplied either from l or by a branch from the retort M. Figs. 186-190 illustrate different forms of liquid fuel injectors introduced successfully by Messrs. Aydon, Wise, and Field, and Figs. 191 and 192 show- arrangements of boiler furnaces used by them. Fio. 186. 'Ayoon's type of injector as useo jx MESsn Fteui^ Fig. 187. ATDOM^ TVK OP IRJSCTDII.I AS useo n wooLWicNAc 3C4 atdon's injectors for liquid fueu Fig. i88. VISE. riELO AND AVDON'S UMPKO-VeO INJECTOR, AS USED AT HILLW/tU^ Fig. 189 Scale 1 Inch _ 4 tnchEt , . . . . Voth, LIQUID FUEL INJECTORS. 305 Fia. 191, Aydon's Syatem applied to a Cornish Boiler, at Messrs. Field's, and at Messrs. Barnes. Fig. 192. Aydon's type of Furnace, as used at Messrs. Barnes. In the Russian oil field, various forms of apparatus have been employed and of late years the use of the pulverizer or injector system in some shape has become almost universal. In the steamers of the Caspian and Volga, the best known and most widely used* pulverizer is that of Lents, which is shown in figs. 193-J96. Fio. 193. • Crtr i , Sectim, GM, * "Engineering," June 22, 1883 ; see also paper by Col. C. E. Stewart, ''Proo. Eoy. U.S. Inst.," June 18, 1886. 306 LIQUID FUEL INJECTOES. Fig. 194. FiQ. 196. It consists of two horizontal iron pipes, to the upper of vhich petroleum is LIQUID FUEL INJECTOES. 307 fed, steam being admitted by the lower, each pipe having a cock for shut- ting off the supply. The two fluids enter the pulverizer at e and f (Fig. 194), but are prevented from mingling by the diaphragm (4). Notches are filed in the edge or lip of this diaphragm (Fig. 195), and through them the petroleum trickles, to be blown off by the steam, which escapes at the under side in jets, with intervening spaces for the admission of air. Two semi- circular slides (3, 3) are used as regulators ; these are kept to their working faces by helical springs, and are worked by eccentrics fixed at the ends of the spindles No. i. No. 2. On the locomotives of the Trans-Caucasian Railway, this apparatus did not succeed, as it blew the flame too directly on the tube plate, and, combus- tion not being complete, the tubes were fouled with soot. But in stationary boilers and on board ship, it is a favourite form of apparatus. FiQ. 197. Artemeff's pulverizer, shown in Fig. 197, is a more simple arrange- ment, the difference being mainly in the means of regulation by cocks instead of slides, as in Lents'. The petroleum and steam enter by two pas- sages, and meet round a portion of the diaphragm, where a slot is cut through the outer casing for the escape of the spray. The diaphragm itself is a conical washer, ground up to a close bearing with the lower and main part of the pulverizer, and held in its place by a cap and a single bolt. The apparatus is generally attached to the boiler by a swing joint, so that it can be turned back and taken to pieces rapidly, without interfering with the working of the boiler. X 2 308 LIQUID FUEL INJECTOES. An ingenious central pulverizer for locomotives, invented by Brandt, is shown in Figs. 198 and 199. The petroleum enters through the central Fio. 198. pipe A, and, overflowing on to the diaphragm b, trickles down to the lip c, where it meets the steam and is driven ofl' in spray. The steam and oil Fio. 199. are regulated by means of separate cocks, which are manipulated from the foot-plate, the burner being pljaoed in the centre of the fire-box in locomotive boilers. When applied to stationary boilers, another form of this pulverizer is used, which is illustrated in Figs. 200 and 201. This forms a conical flame, which has a helical or rolling motion when spiral grooves are cut in the conical head as proposed by Mr. Ludwig Nobel. Karapetoflf's apparatus, which is said to be an improvement upon the LIQUID FUEL INJECTOES, 309 other arrangements tried on the Russian railways, is shown in Figs. 202—204. It is fixed in the fire-box door in such a way as to throw a flat fan of flame Fio. 200. ^iani FlQ, 201. Fio. 202. ' Sjfet^ in^eetor. Fio. 206. rih _ 974 2,241,273 56.58 8.08 .lune . 3Q-74 147,720 48,638* 3,043,384 57-46 8.46 July . 28.39 145,232 51,826 2,652,482 48.69 7-13 August 27.04 152,659 52,697 2,703,475 49.88 6.92 September . 28.93 143,000 50,112 2,693,239 55-49 7.71 October 23-30 163,442 53.837 3,101,778 62.29 8.26 Noyember . 21.60 159,669 43-640 2,508,388 63.88 9.15 December Total and average 20.04 112,118 36,081 1.517,773 ,68.37 9.72 for year . 26.32 1,341,681 474.679 23,253,148 57-25 7.80 With Petroleum Residuum in 1885. Average Aggregate Aggregate Aggregate Average Consump- tion of Fnel and Month. Number Distance run by Locomotives. Unproductive Distance run by Freight Cars. Cost per Mile. Train. Run of Locomotives. Petroleum Kesiduum. Cost. miles. miles. miles. lbs. d. 1 January 22. r4 114,192 46,052 1,509,005 34-43 4.77 February 22 0[ 89,648 37,513 1,148,056 34-09 484 M^rob . 22.58 88,950 33,721 1,097,442 28.98 482 April . 25-33 141,584 46,654 2,354,348 31-73 5.16 May 28.49 179,872 65.985 3,246,003 29.88 4.59 June . 28.35 144,669 55.347 2,533,104 2993 4.28 July . 24-77 131-341 48,001 2,064,742 27-57 3-71 August 28.27 128,559 46,677 2,315.544 28.75 4.17 September 31-89 130,846 46,088 2,703,087 32-07 4.55 October 28.04 125,523 38,266 2,448,912 35-55 5.09 November 21.41 119,788 36.258 2,451,573 35-74 5,21 December Total and average 22.15 1 92,361 34.171 1,287,893 38.13 5-74 for year . 25-45 1,487,333 534.733 25,159,709 32-23 4.50 EESULTS OBTAINED BY THE USE OF LIQUID FUEL. 323 03 P w 1:2 o r <§ g . til -S "^1 s g& u 1^ 1 l-i M t^ s m s S H ji 2 ^ a - ■g be ■o a be . " bji:: * M . s . .s £'s.£Pi:.£P.5?i-3.'E'3 E 2 n'S ° S^^t- 1 = 11-1 I i - + I I o e 13 bc9 P4 „.-,j^ g rn "^ 11 TfOO « li-i tri ON M ON O (^''tiONOOOOOOQOOOOO 00 O On W (^ u-iOO 00 w^ ON On CM fo r^oo vo m "j^ in rrt'O t^ "^ m onoo r^ r->. ^ Ti- r^ t^oo On OnnO t^ONON"^"^ONONf*^ •* ^ '^OO N NO 00 00 ^ « 00 Tj- ^ O I-" ON -^NO NO •* ON vn _ M _■ HH M l-l Mf*^^ N o g I- o ■8IB0 papuo"! [0 •^ ON^ ThTj-Tt-M M TfONO 00 00 >-< t^OO N in 10 N ON ^ .2 f^u-i Ml-. ^ HH 7 OvhH fpr^T^fO^ rOQ H 4o6"Nt:.N^,:^N^ro (N N « M N 83A!;omo3oq S'??f?J?f?"^J5°°*§- 13 • • -M ' • (S J J ^ • • -T, ■ J^ se i -1 C s k to Filon Arcbeda Tsaritsin Taaritsin k to Tsari 1-^ . % M ^^R n m ^ 2^o£5J .5-S n '^M ■= "biSB ^ .5 -5) «.s <« H Eli itto, orisc lone robe rohe oriso 13 e3 cq Qi3afc(<1-( M Tj- mu^ fooo "- Th g ?! ^ CO 1-3 1^ .SP-2 bo 9 .S o ■£3 ^ irj p^ 5n£ CO ia Ph- Pl, o E " l§ VO S f1 II B. II ^n vo ^ II a ^ M 11 (> II ^ .3 a> o - ¥*8 ^ •f i^.. Y 2 324 EESULTS OBTAINED BY THE USE OF LIQUID FUEL. pa n e1 "if s §1 ^1 'I «s s g II I w s ^ ■Si s B 00 M 1 13 1 V. 1 to o5 o — w i ■"1 ' — , - . ^ F — — S ii = -1 s i^ r^ « ^ 00 2-i ^ ir tn A - ■^ lO ON 00 o ^ ^ s :: - M ^ E u o m o fO tN. U^ M & u^ t^ "1 N t-< -o 00 i$ '■d- \o fO ^■?n CX 51 ■3 a u-1 ^ lO 00 rO ■3 ^ ON r^ M ■O M M o u i -S * ^ b S S- -2 *o S ^ t2 1 'o M -s o 4 s <^ ^ ^ f^ AS 8 8 a o .9, Pn 00 00 "a o\ cS ■* ^ •* Th ^ d S 00 00 •+ rh Th Th 00 a fR 5 10 h a rn M '5 91° 1 11 ^' §. 8 8 8 8 8 OiJ H. ^ -^ ■* "J- T|- Tl- •BJBO H pspuoTjo H « M N . , foro ^ M On fO hH t^ ,5 ? V « « N "I" N " (if , li 1 n ft?fi C f s On H O m *■ 5 .00 ■= -S <£ -s •* «' a i 3 Train. Train alone. Train- miles. Fuel. Consumption, inclu- ding lighting up. Cost of Fuel per Train- mile. Gross Load. Total. Per Train- mile. ■3-! 37 14 32' 57 31-34 2J-I2 No. 30 30 30 30 Tons, 480 480 480 480 194 194 19+ 194 Bituminous coal Fetroleumrefuse Anthracite . . Petroleum refvse lbs. 14,084.07 6,175-325 12,784.002 6,103.097 lbs. 72.598 31-831 65-897 31-459 Pence. ! 10.599 j 3-5»i ! 9.621 I 3 539 Prices f Fuel. — Petroleum refu'se, 2i'>. per ton ; anthracite, and litiiminouB coal, 27«. id. per ton. 326 RESULTS OBTAINED BY THE USE OF LIQUID FUEL. g w ■ l-l 13 . l-H S ^ p, 1— 1 Sq^ . cKm oco^ -^ roe» Tj- M ao t^ O^-flt ^ moo tj< "~» foo iri m^ 00 o ^ c>oo «a ."^meo to O vO 00 O N CO CO MO C^ N « a^ OMO -^ -q-co - VOO VO O CO ^ 0) 00 rnia 00 "-)« lOO oa O O^TH > N 00 O t^ O 1 > < s vd ^fH vd -^ ' ■n 1^ 1-1 d ini^ a f, M O « O t^ 1 s \6 -^09 -^yS 1 r^^^ fopo 0\ N rH 00 « 1 t^OO CO iri PO 1 8 R§ 9-^ ' J3 0\^^ N O , ^ ii O tN.lC tN, -^ \0 lOOJ \0 'O 1 a O *OiH r>.00 1 00 mm 11 d 1 OS rN.«3 u-i Tj- w .^ ^ a (S 5 -t^ -"CO ■O'O op "H hhM '^ poi t^^d ^ ■3 * ONUS f-^ Q 1 moo iH \o "O '«j■d^«>vd vd 1 i "*) onc* m m 10 - b- d r^ >-3 e£ 0^ pa 05 "-)p^ 1 Tj- u^« m root- 1^^ ■ § % •S O O _« O O JJ O CS S Ph ■S. -a ^ - a ^ p, Ph o 3 o o « 5 " " 0^ DO S 03 ^ ^ t -f 3 ^ ^ s .SP K Is] OS pE< N s :a :3 a •IS ?>■ o "^ I i RESULTS OBTAINED BY THE USE OF LIQUID FUEL. 327 5. Eesults obtained with the system of a primary gasification of the oil in a separate chamber or retort have already been referred to (under section 3), the retort having been in these cases heated by the furnace in which combustion of the resulting oil-vapour took place. Dorsett's plan of an external gasifying chamber was introduced in 1868 at his chemical works at Deptford, and gave results of great economy. Trials were also carried out in the steamer Retriever of 500 tons burthen and about 90 nominal h.p., and the ratio of evaporative duty was as 2.5 to 2.7, is to I in favour of liquid fuel as compared with coal. Furnaces at Woolwich Dockyard and at Millwall were also fitted up on this system for heating boiler plates, and for shingling or balling scrap iron, and gave a ratio of 2.87 to i in favour of the quantity of liquid fuel used, and a saving in time of heating as 2.5 to i in favour of oil. The relative duty in the scrap furnace was as 1.5, is to i in favour of oil. Eames's plan (as shown in Fig. 184), as applied to a furnace for welding pUes of scrap having a steam boiler heated by the waste heat, and also as applied in another case to a puddling furnace, was very successful, the duty of the scrap furnace being stated at from 7 to 8 times in favour of liquid fuel as compared with coal, and that of -the puddling furnace as 1 2 to I in favour of liquid fuel. A similar system was (under the name of vapour fuel) introduced * on an extensive scale at the works of the Norway Steel and Iron Company, Boston, U.S.A., and applied to steam-raising, puddling, re- heating, and steel- melting furnaces — the latter being a lo-ton open-hearth furnace. Crude petroleum was stored in tanks, and led from them by pipes to the vapour generators,t called " thermogens," in the diiferent parts of the works. A thermogen seems to have been connected with each furnace worked with Hquid fuel, but the regenerative furnaces required merely the air for com- bustion to be heated in the regenerators. All the operations mentioned were carried out successfully with this fuel, and were found to be more entirely under control than when coal or producer gas was used. A considerable saving in first cost, repairs, and cost of fuel is announced, and also a larger output, from furnaces worked on this plan. Archer's oil-gas generator (Fig. 185) has also been used in connection with steel-melting furnaces at the works of the Steel Company of Scotland, Limited, and gave good results as to the economy of fuel, although it is questionable whether the form of this apparatus is the most suitable for continued use. The wide variety in, or the intermittent character of, the results obtained by the different methods of using liquid fuel — and even by the same method under different circumstances — is due to imperfections in the apparatus used, and to want of experience in the best method of treating the fuel. Admiral Selwyn explained the high evaporative rates obtained by him, by assuming that the hydrogen of the steam used in his injectors is burned ; and Mr. Henwood, following in his steps, has claimed for his apparatus that the oil and steam are so proportioned that the hydrogen is fully utilized in the same way in his furnaces. But, inasmuch as, in the dissociation of the hydrogen and oxygen composing steam, an amount of heat is absorbed and becomes latent, which is the same as that developed when the hydrogen is burnt and again combines with oxygen to form water, it is very impro- bable that this view affords an explanation of the results obtained. On the other hand, those who have rejected Admiral Selwyn's view have * " Iron Age," Wov. 22, 18S3 ; "Jour. Irou and Steel Inst.," vol. ii. 1883, p. 749 ; &o. t See " Iron," vol. xxiv. p. 54. 328 CALOEIFIC VALUE OF LIQUID FUEL. not given proper weight to several considerations which belong to thi subject. The estimates made of the calorific value of liquid fuels from their ele- mentary chemical analyses are usually based upon the amount of carbon contained in them as if it were solid carbon, and to be bwned as such. It is, however, beginning to be understood that, even in estimating the calorific power of coal, some alteration is required in this respect, because part of the carbon in it (probably all) does not exist as such in the solid state. In liquid fuels, it is certain that none of it exists in that state, and hence weight inust be allowed to the argument advanced years ago by Aydon. Speaking of liquid fuel, he said : " Here was a fuel naturally prepared the first stage towards gasification, as to effect the same result artificially 6,000 or more heat units would have to be expended, which heat would become latent, and so be lost as useful work. Now, these 6,000 heat units added to 15,000 heat units derived from converting or burning carbon into carbonic acid would give 21,000 heat units, which the late Prof. Hankine stated to be the amount due to gaseous carbon." Aydon "then applied this estimate to the case of American petroleum, and to the creosote or dead oil which he had used at Woolwich. Taking petroleum of the composition, carbon 86, hydrogen 14, if the value for gaseous carbon were employed, it would give this a calorific value of 26.887 lbs. of water per lb. of oU. The dead oil as analysed by Prof. Church, contained— Cavbon . . 86.48 Hydrogen . ^.06 Oxygen, &c. . . . 6.46 Estimating its calorific power as if the carbon were solid, it would give 17.50 lbs. water per lb. of oil, whilst on the basis of gaseous carbon it would give 22.18 lbs. In addition to this point, that the physical state of liquid fuel represents so much latent heat, we have to remember that the carbon which it contains is also combined with hydrogen in hydrocarbons of some kind. These com- pounds of carbon are very readily dissociated by heat, especially in presence of steam of high temperature, and the result of this action is the formation of gaseous hydrocarbons which have a high calorific power. There is reason to believe that these reactions are accomplished with the expenditure of a moderate amount of " work " in the shape of heat. The temperature at which steam is dissociated in the presence of gaseous carbon must be less than that which is required with steam and solid carbon by at least the equivalent of the quantity of heat which becomes latent in gasifying the carbon in order that it may unite with the oxygen of the steam to complete the action ; H^O -I- C = H^ + CO. When the steam is thus decomposed, there is nascent hydrogen in contact with carbon in the gaseous form in some of the heavier hydrocarbons, and there is thus present the opportunity for the formation of those gaseous hydrocarbons which are desired and which ignite at a higher temperature. The oxygen of the decomposed steam may either unite with part of the carbon to form carbonic oxide, or, if left uncombiaed in the primary reactions, it is ready to support combustion subsequently, and this it does, as is well known, with vigour. For the proper carrying out of these reactions, certain conditions are necessary. The suitable temperature for the various reactions must be maintained, with sufiicient time to enable them to be completed before the application of the heat of combustion is required (that is, before heat is abstracted by the requirements of the furnace). There must also be a proper relation between the steam and oil, whilst the air for combustion CALOEIFIC VALUE OF OIL GAS. 329 should be carried to another point in the furnace, and not admitted with the steam and oil. In fact, full consideration of the matter points to some method of primary gasification of the oil with steam before combustion with air as the most Hkely to yield the highest results in constant work. This account of the actions involved in the proper use of liquid fuel is confirmed by the evidence of the results of ordinary oil-gas manufacture. In one important particular — namely, the quantity of gas produced from oil — there is a great difierence between the processes which we compare. Gas which is to be used for lighting must be cooled and purified from condens- able matters before being stored and conveyed or distributed in pipes. Consequently, we find that in the processes of Pintsch, Keith, Rogers, and others, whilst about 150 cubic feet* of gas per gallon of oil used are stored for illuminating purposes, there is a liquid residue from the manufacture amounting to about 6 gallons per 1,000 cubic feet of gas made. These liquid hydrocarbons are quite suitable for gas-making, and in some cases the gas-making apparatus has been worked with them exclusively for the production of illuminating gas. In making use of liquid fuel for heating operations, it will readily be understood that all the original oil is com- pletely gasified, so that the quantity of gas produced per gallon of oil is in that case probably from 250 to 300 cubic feet. The quality of gas made by the two methods may, however, be fairly considered as comparable, since the conditions can certainly be very nearly approximated in the two cases. The following is an analysis of the gas produced by the apparatus of Messrs. Rogers, in which the oil is injected into red-hot retorts by steam, the oil used being a heavy hydrocarbon (its flashing point being given at 250= F.):- Oxygen 0.73 Nitrogen Luminiferous livdrocarbons Marsh gas . Hydrogen 5.06 16.29 46.17 31.61 Carbonic oxide . . . 0.14 The following figures give the thermic value of this gas, on the supposition that the " luminous hydrocarbons " mentioned in the analysis are ethylene of the composition C^H^. If the composition CjHj had been assumed for these hydrocarbons, the heating power would have been considerably higher. Evaporative power of gas per lb. . . = 40.75 lbs. „ cub. ft. = 1.622 „ Fahr. heat nnits per lb. . 21,843 „ cub. ft. 869.3 Calculated sp. gr. of gas .4941 On the supposition that 25 to 27 cubic feet of such gas are produced per lb. of oil, these figures result in giving a theoretical evaporating power oifrom 40.5 to 43.79 lbs. of water per lb. of oil when completely turned into gas with steam. This gas is stated to be of 56-candle power, and the results obtained from experiments made (at the Surgeons' Hall, Edinburgh, and in Glasgow by Dr. Wallace) on specimens of Scotch crude oils show that gas of even higher heat- ing power may be obtained from oil of the kind used for fuel. The following table (published in the " Glasgow Herald " of Decem- ber 10, 1886) gives the results of these experiments collected and arranged * Processes employing distillation alone, yield about 90 cubic feet per gallon of the inter- mediate quality of oil used. 330 MINOR FUELS. for comparison with the yield of gas from several of the best Scotch cannel coals : — 1 Gas per Ton. Candle Value per Ten i Cubic Feet. Power. in lbs. Sperm. 1 West Lothian oil .840 sp. gr. 24,922 60.15 5,139 i .. » -89° >. 23,573 55-29 4,469 .. -870 „ 24,383 56.26 4,702 i ,, -, -870 „ 24,396 57-65 4,822 Westfield oil (cniile) . ifi,755 49-03 2,815 Walkinshaw oil .653 fp. gr. 19,464 40.23 2,683 Boghead coal ... 14,900 42.19 2,157 Cairntable coal (1872) 11,294 35-75 I,384i Haywood coal (1884) .... 11,360 32.12 1,251.02 Lesmahagow, Auclienheath coal (1882) 13,201 34-52 1,562.39 The quantities of gas yielded per ton, and the comparative values per ton of oil or coal in lbs. of sperm, are, of course, given on the basis of gas being made and stored for illuminating purposes. The table, however, reveals a store of heat-producing energy in oils of low quality which has not yet been utilized, if recognized.* It is evident that it is on its ability to produce gas of high calorific power that the value of the liquid form of fuel rests, and that, in order to use this fuel successfully, efforts must be directed to the complete production and utilization of this gas. The evidence before us points to the conclusion that with suitable apparatus it may be possible to obtain, continuously, results equivalent to an evaporation of from 40 to 50 lbs. of water per lb. of oil. Such results have been obtained at rare intervals in the experiments already made, but in general they have been considered as abnormal, and possibly incapable of a reasonable explanation. MINOR PTJELS. In certain localities, especially where a better quality of fuel is not easily obtained, refuse vegetable matters are used as fuel for steam raising. Thus, spent tan has been frequently employed, and straw has also been used for portable agricultural boilers ; both " megass," or the refuse from the sugar- cane, and cotton stalks are also among the substances used. AU these materials are frequently referred to as minor fuels. Prof. E. H. Thurstonf investigated the performance of spent tan, both air-dried, weighing 42^ lbs. per cubic foot, and also containing from 55 to 59 per cent, of moisture as it came fresh from the leaches. By the combustion of wet tan, from 3^ to 4J lbs. of water were evaporated per lb. of tan ; or, allowing for the excess of moisture in the tan, from 4.41 lbs. to 5.68 lbs. of water per lb. of air-dried tan. Peclet, quoted by Mr. D. K. Clark, found that five parts of oak-bark produce four parts of dry tan, and the heating power of perfectly dry tan, containing 15 per cent, of ash, is 6,100 British units, whilst that of tan in an ordinary state of dryness, containing 30 per cent, of water, is only 4,284 units. The weight of water evaporated from and at 212° F. by i lb. of tan equivalent to these heating powers is : — For perfectly dry tan . . . . . . .6.31 lbs. For tan containing 30 per cent, of moisture . . . 4.44 „ Mr. J. Headi states that 3.25 to 3.75 lbs. of average dry wheat straw * Befer also to W. Ivison Macadan on The Manufacture of Gas from Paraffin Cil, " Joum. Soo. Chem. Indus.," 1887, p. 199. + " Min. Proc. Inst. C.E.," vol. xl. p. 347. X Ibid., vol. jdviii. p. 75, &o. Also " A Fe-w Notes on the Portable Steam Engine," 1877. THEORY OF HEAT. 33 1 will evaporate as much water in the same time as i lb. of good coal in a modern boiler. The relative commercial value of the fuels is, however, as i to 5, because 3,300 lbs. straw, costing about 44s., are equal to 943 lb«. coal at 8«. 6d. Mr. Head also gives results with the use of "megass" and cotton stalks, and states generally that in portable engine boilers from 2| to 2| lbs. of water are evaporated per lb. of "megass " containing 16 per cent, of moisture, and from 2 1 to 3 lbs. of water per lb. of cotton stalks or brushwood. • THEORY OF HEAT. Various theories have been held as to the intimate nature of heat. In •what is probably the first scientific hypothesis on the subject, Bacon described heat as a vibratory motion of the smallest parts of bodies, and this view was in the main held until partly effaced, in the last century, by the suggestion that heat is an imponderable substance. In 1 799, however, Davy and Rumford conclusively proved that heat can be generated by mere friction ; the former described heat as being caused by motion, the latter identified it with motion. Of the two alternative theories — the material and the dynamical — it may be correctly said that the capabilities of neither have been exhaustively studied. In certain cases, it is stUl perfectly possible to reason fruitfully on the theory that heat is an imponderable chemical substance ; and on the other hand, the dynamical theory is not one of pure motion, but invariably considers the motion of material particles. The two theories are thus more closely akin than is usually supposed. If we adopt the current view that matter consists of atoms or molecules surrounded by setherial envelopes (as the earth is surrounded by its atmosphere), we may raise the question, Is the motion that causes heat a motion of the atoms, of the ether, or of both 1 Physicists have found insurmountable obstacles in any other theory than that heat is some kind of atomic motion. Modern ideas on the subject of heat derive most of their distinctness from the discussion of Mayer (1842) and the experiments of Joule (1843), who showed that heat is a perfectly measurable mechanical quantity ; the latter investigator in fact determined the amount of heat produced in various ways, and in particular by friction between solids and liquids. This definite relation between heat and work — which indeed holds true whether work causes heat or heat causes work — is called the Mechanical Equivalent of Heat. It is quantitatively expressed in the following statements : — In order to raise the temperature of i pound of water i degi'ee F., the mechanical energy to be expended is that of 772 pounds falling i foot : or in French units, 424 kilogram-metres are required to raise i kilo, of water 1° C. This result is commonly known as the first principle of thermodynamics. Although this equivalence of heat and work may be regarded as certainly established, we can readily see that it is subject to what may be termed " actual " limitation. It can only hold good when we transfer heat from a warmer to a colder body, or, what is the same thing, when we transform heat of a higher temperature into heat of a lower temperature. It is the more quickly vibrating body which loses motion to the more slowly vibrating body. Thomson expresses this result as follows : — " It is impossible, by means of inanimate material agency, to derive mechanical eflfect from any portion of matter by cooling it below the temperature of the coldest of the surrounding objects." This is the second principle of thermodynamics. Considerations as to the efficiency, of engines mainly depend on the second principle. It is not sufficient to consider, for example, the heat 332 RELATIVE VALUE OF FUELS. given out by the combustion of a fuel, unless we also bear in mind the temperature of the environment. In oth&c words, the portion of the total energy of a fuel that can be thus exchanged for work, depends on the relative temperatures of the boiler and condenser. The mathematical ex- pression of this law (for a perfect, or reversible engine) is — W ^ T-t . H 273 + r' where W represents the work performed by the engine, H the heat actually communicated to it, T is the temperature (C.°) of the boiler, and t that of W the condenser. The fraction _r represents what is called the " efficiency " II of the heat engine in mechanical units ; and this evidently depends on the difference between the temperatures of the boiler and condenser. The temperature —273° 0. has been approximated to, but not actually attained, experimentally. It is usually known by the name "absolute zero;" which implies that all bodies when at that temperature cannot in any way be regarded as sources of heat. EELATIVB VALUE OP FUEL. JDiiferent kinds of fuel are by no means capable of producing a like amount of heat, and it becomes both interesting and highly important to learn the methods which science has adopted for ascertaining their maximum heating effect. The results obtained from these researches are called the theoretical calorific effect ; and in order to ascertain this, it is necessary to know the quwntity of heat which a certain amount of fuel is capable of pro- ducing, and the time which is required for effecting that object. These two points furnish the idea of what is called heating power. The value of the fuel depends on its heating power, and its price at the time of consumption; it varies, therefore, in different localities, and can only be relatively fixed. The determination of the first point (the quantity of heat) with accuracy is exceedingly difficult ; but for practical purposes a knowledge of the absolute quantity is not required, it is sufficient to know how much the heat produced by one kind of fuel exceeds or falls short of that produced by another, the actual quantities produced by each being undetermined. Several methods have been employed at different times to ascertain this relative heating power. The more ancient, purely physical experiments, undertaken by the most distinguished men of science, were all conducted on the same prin- ciple, that of causing the whole of the heat which a burning substance or fuel emits, to act on a third body, in order to compare the action which the different kinds respectively had upon it. The apparatus by which this was done, is the well-known caloriineter. Lavoisier and Laplace caused the heat evolved in this apparatus to act on ice, and measured the amount of heat by the quantity of ice that was melted. At a later period, Count Eumford, to whom we are indebted for many experiments on fuel, used water instead of ice, and measured the heat by the increase of temperatiu'e produced in a given quantity of water. Both methods of determination are in fact the same, the quantity of heat which will melt i lb. of ice at 0°, being just sufficient, according to Lavoisier and Laplace, to'raise the temperature of as much water (i lb.) 75° C. ;* or what is the same thing, to raise 0.75 lb. of water 100° C. Clement and Desormes have likewise shown, that an equal weight of aqueous vapour, whatever may be its temperature and tension, is always produced by one and the same amount of heat, and con- * From the more recent and accurate experiments of de la Prevostaye and Desains as well as from those of Begnault, it appears that this number must be raised to 79°. EUMFOilD'S EESULTS. 333 sequently always contains that same quantity ; and, farther, the quantity of heat which water at ioo° C. absorbs (latent heat) in a manner no longer indicated by the thermometer, in order to be converted into vapour, is 5.5 times (according to Rumford, 5.67) as much as would suffice to heat the same weight of water from 0° to 100° C. According to the later and more exact researches of Eegnault this value is 5.367. It is therefore easy to cal- culate how much water would be converted into vapour by the heat that is required to melt i lb. of ice. Eumford's experiments, which only extended to the different kinds of wood, led to the following results : One Pound of the fallowing Kinds of Wood, wlien burnt, will heat : I. Lime-tree. Dry wood, 4 years old „ „ slightly dried ,, „ strongly dried . 2. Beech. Dry wood, 4 or 5 years old „ „ strongly dried . 3. Elm. Wood, rather damp . ,, dried, 4 or 5 years old . „ strongly dried „ dried brown . 4. Oak. Common firewood, in small shav- ings .... The same in thicker shavings ,, thick shavings ,, dried in the air. Very dry wood in thin shavings I) )) thicker „ 5. Ash. Common dry wood . The same dried in air, shavings The same, shavings dried in an oven ..... Founds of Water from 0° to 100° C. 34-707 38-833 40.131 33-798 36.746 32-147 30.205 34-083 30.900 26.272 25.590 24.478 29.210 29-838 26.227 30.666 33-720 35-449 One Pound of the following Kinds of Wood, when burnt, will heal : 6. Sycamore. Strongly dried in an oven . 7. Mountain Ash. Strongly dried in an overt Dried brown . . . . 8. Bird Cheny. Dried wood . . . . Strongly dried in an oven . Dried brown . . . . 9. Fir (Deal). Ordinary dry wood . Well dried in tlie air, in shav- ings .... Well dried in an oven, in shav- ings _ Well dried brown, in shavings . Well dried, in thick shavings 10. Poplar. Wool dried in the ordinary manner . . . . Wood strongly dried in an oven . . . . . II. Hornbeam. Dried wood (ordinary) Pounds of Water from ooto loo^C. 36.117 36.130 32.337 33-339 36.904 34-736 30-322 34.000 37-379 33-358 28.695 34-601 37.161 31-704 By means of instruments of the same kind, the following results have also been obtained : lb. of hydrogen will raise the temperature of 234 lbs. of water pure carbon ,, „ 72 ,, wood charcoal ,, ,, 75 ,, dry wood „ „ 36 „ wood containing 20 per cent, of water „ „ 27 „ good coal , „ 60 „ P^^t ,. II 25—30 ,, alcohol . „ „ 67 „ ether ■ ,, , 80 „ vegetable oil, rape oil, wax oil, &c. „ „ 95 „ „ / The same quantity of heat being required to raise the temperature of TOO lbs. of water 1° as in heating i lb. of water 100°, it follows from the above results, that — 334 lb. CALOEIMETERS. of hydrogen , vegetable oil, rape- will, raise the temperat ure of 23,400 oil, wax, &c. , ether , pure charcoal , wood charcoal , alcohol , good coal , dry wood , wood containing; 20 n }) 9,000- -9-500 8,000 7,200 7-500 6,700 6,000 3,600 per cent, moisture , peat ti 2,500- 2,700 —3,000 Hydrogen . 324 Vegetable oil, &o. 1.23— 1.30 Ether . 1.09 Gas-carbon . 1.07 Wood charcoal . 1.02 The numbers placed against the different combustibles in this table, or the quantities of water which i part of a combustible will raise 1° C: in temperature, represent units of heating power — ^the quantity of heat neces- sary to raise a given quantity (i lb.) of water 1° C. being assumed as unity or the standard of comparison for the eiTects of heat. If the heating effect of pure carbon be taken as unity, the relative heat- ing values of the other combustibles will range as follows : Alcohol . . . 0.92 Good coal . . 0.77 — 0.82 Dry wood 0.49 Wood with 20 per cent, water . o. 37 Peat 0.35—0.41 It appears from this table that the absolute heating effect of hydrogen is nearly 3 times as great as that of carbon. The greater the quantity of hydrogen, therefore, contained in any com- bustible body, the greater will be its beating effect. Regnault's apparatus (see Ganot's " Physics," p. 356 ; " Chemistry, &c.," art. " Fuel," W. Mackenzie, Glasgow), although designed for the de- termination of specific heats, contains features illustrating the method of observing and measuring temperatures, and the precautions against error which are necessary. Favre and SUbermann's calorimeter * (see Watts, " Diet, of Chemistry," Second Supplement, pp. 608, &c.) is likewise a delicate apparatus suitable specially for determining the calorific capacity of liquids, the latent heat of evaporation, and the heat disengaged in chemical action. Thompson's calorimeter, represented in Figs. 217-219, is an instrument for determining the relative Fio. 217. 22 grams of a very dry mixture of value of fuels— indeed, it is the only one generally em- ployed for that purpose. It consists, as will be seen in the accompanying diagram. Fig. 218, of a glass jar, h, graduated to contain 1,934 grams of water. In this are inserted (i) a thermotieter to indicate elevation of tem- perature, and (2) a cylindri- cal combustion chamber, g, capped and'tappedatthetop. The combustible to be ex- amined (2 grams) is mixed as intimately as possible with 3 parts of potassic chlorate with i of * See also W. Anderson, " On the Generation of Steam, &c.," Inst. C.E. Lectures on heat and its mechanical applications. Snssions 1883-84, p. 5. CALOEIMETEES. 335 nitrate, and introduced into a small cylindrical copper reservoir, E ; a piece of nitrate of lead fuse, f, is added and lighted. The combustion chamber or cap is closed and instantly caused to cover the reservoir, and the whole is placed without delay in the water of the calorimeter. Gases soon issue from orifices at the lower edge of the chamber, and rise through the liquid, imparting their heat to it. "When combustion has ceased, the rise in tempera- ture of the water is observed ; to this, one-tenth is added for the water-value of the calorimeter. The corrected number gives the number of grams of water which a gram of the combustible can evaporate at the boiling point. Fia. 218. Fia. 219. |i|i| 11 Calorimeter in Action. Combustibles that burn too easily require the addition of 0.5—1 gram of china-clay, purified by roasting in air. The apparatus can, if desired, be caUbrated by burning in it a known quantity of pure sulphur. Thompson's calorimeter is made by Wright, of Millbank Street, London, S.W. Prof. P. Sohwackhofer has designed and constructed a calorimeter for determining the calorific power of coal or other fuel. It has a platinum com- bustion chamber divided into two parts, in the lower of which the sample is burned by means of oxygen gas, which is led into the apparatus. The heat is measured by the rise of temperature of a measured quantity of water. For full details of the apparatus, the original paper must be consulted in Zeit. anal. Ghem., vol. xxiii. p. 453, where it is described. A short abstract and illustration are given in " Jour. Soc. Chem. Indus.," 1885, p. 332. See also " Jour. Soc. Chem. Indus.," 1886, pp. 635-637, for description of Heisch and Folkard's instruments. A most remarkable connection between the quantities of heat evolved, and the chemical process of combustion, was first pointed out by Welter in the calorimetrical experiments of Laplace, Lavoisier, Despretz, Eumford, and others, and gave rise to a new and more convenient method of deter- mining the heating power. Welter observed that those quantities of a com- bustible body which require an equal amount of oxygen for combustion, evolve also equal quantities of heat, as is shown by the following examples : I lb. of: will heat lbs. of Water from 0° to 100'' C. Or, I lb. of Oxygen in consuming : will heat lbs. of Water from 0° to 100° C. Hydrogen Charcoal Perfectly dry wood . 236.4 Despretz 78-15 43.141 Eumford 0.125 "j. 0-375 „ 0-724 „ 2.955 2.931 3-093 336 ABSOLUTE HEATING EFFECT. In the greater number of combustible bodies, the differences observed were not greater than might have been anticipated from the difl5.culties attending all calorimetrical researches, whilst in others, as phosphorus iron, &c., they were twice as great. Welter therefore drew the conclusion that the oxygen required for the combustion of a body being in the same relation as the quantity of heat evolved, might fairly be made the measure of the heating power. In fact, we are led, a priori, to this supposition, if we consider that, on the one hand, the heat evolved must bear some relation to the mass of the body burnt ; and, on the other, that oxygen may with equal propriety be considered the combustible, as the body with which it combines (the fuel). When, therefore, oxygen burns by means of carbon, wood, hydrogen, &c., the heat which is evolved must increase with the quantity of it that is consumed ; or the same amount of heat is generated by a certain given weight of oxygen, whether that qiuintity be employed in converting carbon into carbonic acid, or hydrogen into water. The amount of heat generated can easily be calculated from the experimental results given at p. 333. For as , . and I part of carbon requires for combustion 2| parts of oxygen, and I „ hydrogen „ „ 8 „ „ I part of carbon will raise the temperatare of 72 parts of water, and I „ hydrogen „ „ 234 „ from the freezing to the boiling point, it follows directly that 72 I part of oxygen in burning carbon will heat — = 27.0 parts of water, I part of oxygen in burning hydrogen will heat -|4 = 29.3 „ „ from the freezing to the boiling point. In round numbers, therefore, the heating effect of oxygen may be assumed at 28 or expressed in units of heating power at 2800. Absolute Heating Effect. — If, therefore, . the quantity of oxygen required by i part of a combustible be denoted by 0, the absolute heating power of that combustible may be expressed by the equation (i) ^ = 28000 or .4 = 2800 -, a in which latter formula, n = the number of oxygen atoms with which the body combines during combustion, and a = the atomic weight of the sub- stance, that of oxygen being = i. The number obtained by means of either of these equations consequently indicates the amount of water which will be raised 1° 0. in temperature by the heat generated during the combustion of i part of the combustible body. The formula may easily be extended for bodies containing more than one eombustible element. Let a fuel contain ah c d parts by weight of different combustible ingredients, which respectively combine with 0' 0" 0'", parts by weight of oxygen, then (2) A = 22,oo\aO + hO' + cO"+ J orA = 2?,oo\aV: + b'^ + c- + 1 (4) L a /3 7 J In the latter formula n n' n" . . . denote the number of oxygen atoms with which i part of the corresponding combustible bodies combines; a ^ y . . . denote the equivalent weights of those bodies. ABSOLUTE HEATING EFFECT. 337 The second formula is deduced from the first by making = *^, 0' = *^', 0" = -.... a fi y The general correctness of Welter's theory has not been proved, indeed recent researches (as will be stated presently) tend to invalidate it ; but G. Bethke and F. Liirmann have advanced some considerations founded upon the latent heat of the gasification of carbon which go far to remove the doubts thrown upon it by these later researches. Berthier founded a practical process on Welter's theory to determine in one experiment the quantity of oxygen requisite for combustion, and thus the heating power of the combustible. It consists in mixing intimately a weighed quantity (lo grs.) of the combustible with a large excess (400 grs.) of pure litharge (protoxide of lead). The mixture is placed in a crucible, sufiiciently capacious to contain 3 times the bulk of the mixture, and rendered impervious to the gases of the furnace by a coating of fire-clay or by a glaze, and is covered with an equal quantity of pure litharge. The crucible, being covered with a lid and placed on a support in a furnace, is slowly heated to redness, and when the gases which cause the mixture to swell considerably have escaped, the crucible is covered with fuel, and strongly heated for about ten minutes in order to collect the globules of reduced lead into a single button at the bottom of the mass of fused Ktharge. The oxygen of the oxide of lead com- bines with and burns the combustible ingredients of the fuel, leaving for every equivalent of oxygen consumed an equivalent of reduced metallic lead. It is, therefore, only necessary to weigh the metallic lead, which is easily separated from the fused litharge by a few strokes of the hammer, in order to discover the amount of oxygen consumed and the relative heating power of the fuel. If, however, it is required to ascertain the quantity of water heated up to 1° or 100° C, it is necessary to refer to the known calorimetric power of a single combustible body, and carbon is then usually made the standard of comparison. Now i part of pure carbon requires 2.666 parts of oxygen, which, taken from litharge, leave 34.5 parts of metallic lead; the same quantity of carbon, according to Despretz, is suificient to heat 78.15 parts of water from 0° to 100° ; so that every unit of lead that is reduced by any kind of fuel corresponds with — 2.265 parts of water, which it can raise from 0° to 100° C* Taking the corrected numerator 72.26 this becomes 2.095 P^'Cts. An elementary analysis, in which the substance is completely consumed — its carbon being converted into carbonic acid and its hydrogen into water — affords a convenient means of calculating approximately its heating power, compared with that of carbon as unity.t If H is made to denote the percentage amount of hydrogen, and C the percentage amount of carbon, in any kind of fuel containing only carbon and hydrogen, the heating power of hydrogen being approximately 4.25 times that of carbon, the absolute heating effect A of the fuel will be expressed by« the formula : A = 4.2SH + C. (3) But if, at the same time, along with carbon and hydrogen, the fuel also contains oxygen, and this is already in combination either with carbon or with hydrogen, it of course must diminish the absolute heating power of the fuel, and as i equiv. of carbon takes up 2.666, and i equiv. of hydrogen takes treble ' Practical experiments on a large scale, as well as elementary analysis, have shown that the determinations made with litharge are liable to a constant error, and afford results which are always about i below the actual calorific power. t See "On the Estimation of the Oalorifio Value of Solid and Liquid Fuel," by P. J. Eowan, "Jonm. Soc. Chem. Ind.," 1888, p. 195. Z 338 HEATING POWEES EEFEEEED TO VOLUME. that quantity — namely, 8 parts of oxygen — we have to deduct from the sum of both, the quantity of oxygen actually present in the combustible — that is, supposing it is known to be already in combination — in order to ascertain the quantity furnished from without, which then becomes the measure of the heating power ; e.g., in oak-wood there are : 0.4943 parts carbon, and 0.0607 hydrogen, which would give 0.4943 X 2.666 + 0.0607 X 8 == 1. 318 + 0.485 = 1.803. If the oxygen in the oak-wood, viz., 0.445, i® deducted from that quantity, we obtain i .803 -^ 0.445 = i -358 as the amount of oxygen required, coixespond- ing to 17.58 of lead reduced, or to 39.8 of water, which would be heated to 100° C. by one part of oak-wood. Or, as i part of oxygen is combined in 3arbonic acid with | parts of carbon and in water with \ of hydrogen, and we designate by the quantity of oxygen contained in the combustible, its absolute heating effect A will be expressed by one or other of the following formulse, according as the oxygen is supposed to detract from the heating effects of the carbon or hydrogen : A = 4-25[H-|0] + C. (4) To convert the product from either of these equations into units of heat- ing power, it is only necessary to multiply by the heating power of carbon = 7226. As an example, the heating power of alcohol may be thus calculated. The elementary composition of alcohol is expressed by the formula : CjH,0, and it contains in 100 parts : Carbon . . . . . .52.66 Hydrogen . . . . 12.90 Oxygen 34.44 The one half of the oxygen in alcohol, according to the formula, is already combined with hydrogen to form water. The heating power of alcohol will consequently be = 4.25 (0.129-^.^.0.3444) -I- 0.5 266 = 0.85, which agrees very closely with the experimental number given in the table at p. 334. Heating Power referred to Volume. — This property of a combustible is expressed by the amount of heat which' a certain volume of the com- bustible yields during perfect combustion. The absolute heating power being ascertained, it is only necessary to multiply that by the specific gravity of the combustible in order to obtain its specific heating power. The following table exhibits the specific heating power of the combustible bodies enumerated in the tables (p. 334), the heating power by volume of pure carbon (diamond) being = 100. Dry wood 5-26 Wood charcoal . . . • 4'94 Wood containing 20 per cent. moisture 4'9i Hydrogen 0.0077 The specific gravities from which the numbers in the above table have been deduced are the following : Diamond = 3.5, coal =1.5, vegetable oil = 0.92, ether = 0.7 2, alcohol = 0.8, dry wood = 0.4, wood with 20 per cent, moisture = 0.5, wood charcoal = 0.1 8, hydrogen (compared with water) = 0.00009. For the specific gravity of porous substances, such as wood and wood charcoal, numbers have been taken which have reference to those sub- stances in the usual state when their pores are filled with air. Pure carbon (diamond) 100 Good coal . 33-00 Vegetable oil . . 30.20 Ether 21.10 Alcohol .... 19.80 PYKOMfiTKICAL HEATING EFFECT. 339 PYBOMETERS. Pyrometrical Heating Effect. — The pyrometrical heating effect of a combustible is expressed by the degree of heat developed during its complete combustion. Various instruments have been constructed for the approximative estimation, in a direct manner, of the high degrees of tem- perature which most ordinary combustibles produce during combustion ; but none of the older instruments, which were called pyrometers, attained such a degree of perfection that their indications could be considered trustworthy. "Wedgwood adapted the progressive contractility of clays at very elevated temperatures to the construction of the pyrometer which bears his name. The instrument consists of a plate of copper, upon which two strips of the same metal gradually converge to one point, between which small truncated cones of clay are inserted, these latter passing farther forward towards the point at which the two strips meet in proportion to the contraction which the clay has undergone by exposure to different high degrees of temperature. Great care is required in the preparation of the clay for these small cones ; it should always be of the same composition, and, containing an equal amount of water, should be baked at the same temperature. The diminu- tion of volume which clay sustains at higher temperatures is partly due to a loss of water, and partly to a closer agglomeration of the particles in obedience to some law yet unknown. Incipient redness has been adopted for the zero point on Wedgwood's scale, and is the point at which the cones, having been heated to that temperature, are arrested by the strips of metal 240 divisions are traced upon one of the strips beyond that point, each one of which corresponds to 72° of the centigrade thermometer (130° F.). In order to ascertain the temperature of a furnace by this pyrometer, one of the small clay cones is placed in a crucible, in which it is allowed to acquire the temperature of the furnace ; it is then withdrawn, and when cool is inserted between the two metallic strips ; the point at which its farther progress is arrested then indicates the temperature to which it has been exposed. The difficulty of securing at all times the same quality of clay, and conse- quently the same contraction for the same temperature, renders this pyrometer next to useless ; indeed, it is now no longer in use in the Stafford- shire potteries, where alone, at one time, it was extensively employed. The constant temperature at which certain metals and alloys enter into fusion may be employed to a limited extent for estimating high temperatures. M. Princep employed 10 alloys of gold and silver, containing each an in- crease of y'^ of gold; aiid 100 alloys of gold with platinum, in which the latter Aetal is progressively increased by ^^th. By placing a number of these alloys in pieces of the size of a pin's head upon a cupel of bone-ash in which small cavities for the reception of each alloy have been made, and introducing this into any furnace, the temperature of which is to be deter- mined, the alloy at which fusion has been arrested may be observed when the cupel is withdrawn. The temperature of two furnaces can thus be directly compared ; but in order to arrive at a knowledge of the exact tem- perature of any, it is obviously necessary to ascertain the precise thermo- metrical degree at which each alloy enters into fusion. This has been done by M. Princep for the points of fusion of silver and several of the alloys of gold, by measuring the dilatation of air confined in a vessel of pure gold. The results of his experiments on these points are the following : Ked heat .... 649° C. (1200° F.) Orange heat . 899 Silver fuses 999 Silver with ^ jmld . Silver with J golJ . 1121 (1650 (1830 (2998 (2050 Z2 340 PYROMETERS. Daniell proposed the linear expansion of platinum as a pyrometrical standard, and the mode of applying his instrument to the measurement of furnace temperatures is familiar to every student of the elements of natural philosophy. For the accurate measurement of high temperatures, instruments similar to the air thermometer have been proposed by Deville and Troost and by Regnault, the essential modification being the employment of a vapour much heavier than air, and therefore susceptible of determination by the balance. Deville and Troost's pyrometer consists of a sphere of refractory porcelain, having a capacity of about 500 c.c, and provided with a narrow tubulus, into which a stopper of the same porcelain fits loosely. Some iodine having been placed in the flask and the plug inserted, the whole is introduced into the place whose temperature is to be determined. Iodine vapour soon escapes from the flask, driving out all the air before it. In about twenty minutes the flask will have acquired its maximum temperature, and iodine will cease to be evolved. The plug is then sealed to the end of the tubulus by means of an oxyhydrogen blowpipe, and the flask cooled, cleaned, and weighed. The end of the tubulus is then broken under water, and the water which then enters the flask is weighed together with the flask. The flask, if necessary, is next filled entirely with water, and again weighed ; lastly, it is weighed dry. The observer is now supposed to be in possession of the following information — viz. : Temperature of the balance . . . . . . t° C. Height of barometer corrected . . . . . h mm. Difference between weight of flask full of iodine vapour and flask full of air ....... gram Capacity of flask ... . . v c.c. Residual air . . . . . . . a c.c. Weight of I c.c. normal air . . .001293 gram Density of iodine vapour referred to ail- . 8.716 Co-efficient of expansion of air (1° C.) .... .00367 Co-efficient of cubical expansion of porcelain (1° 0.) . .0000108 and the temperature T is calculated as follows : — l^ ^ iv—a).ooi2g3h ^ ^ (i -(-.oo367«)76o is the weight of iodine vapour at sealing ; and the corresponding volume is — J _ I„(i -i-.oo367T)76o .001293 X 8.716/i Finally, we have the relation — T , a(i + .oo367T)76o , , o™< Iv + —h ^ J '' = ■■y{n-.ooooio8T), (i-f .003671)/* ^ ' which only contains one unknown quantity T, the temperature sought. Eegnault's mercury pyrometer is simflar in principle. It consists of a wrought-iron bottle in which mercury is placed, and the mouth of which can be closed by a perforated stopper sliding horizontally. The capacity of the flask is about a litre or half a litre. After acquiring the temperature of a heated space (a point not so easy to ascertain as in the case of the iodine pyrometer), the stopper is slid over the orifice and the flask is removed and cooled. The mercury remaining in the bottle is removed and weighed. The foil owing are the requisite data : — V = capacity of the bottle in c.c. at 0° C. ; k = co-efficient of cubical expansion of iron ; PYROMETERS. 341 h = corrected barometric reading when the flask is withdrawn from the furnace ; . ; rf= density of mercury vapour ; " p = grams of mercury remaining in the bottle. The weight of mercury vapour which fills the flask at T (the required temperature) is — _ ^(i + AT).ooi2932/ifZ _ ^ ( I + .003671)760"' hence, i+^T ^ 76°y ^ ^P 1 + .00367T .0012()^2vdh li M being a constant for the same bottle. We have, therefore — T = i-Mf h .oo367M^ — /!; Ducomet proposed the employment of a series of alloys of known melting point. These are introduced into a tube (or space otherwise protected) having the temperature required to be known. As their melting points range above and below the temperatiire of the medium, it is easy to ascer- tain this approximately either by ocular observation or by feeling the alloys with an iron rod. It must be remarked that the same samples of an alloy will not retain the same melting point after repeated trials, so that they should be used once only, or at most a very few times. This method has been greatly developed by Carnelley. From a long series of determinations which he has published in the Transactions of the Chemical Society for 1878 and 1880, the following may be selected as likely to prove of greatest service : — Substance. Sddic chlorate Sodic nitrate Potassio nitrate Potassio chlorate Plumbic iodide Zinc bromide . Cadmic iodide Baric chlorate . ■ Argentic bromide Cuprous chloride Zinc iodide Argentic chloride Tri-argentio phosphate Cnpric chloride . Strontic iodide . Argentic iodide Cadmic chloride Borax Melting Puint C. 302 316 339 359 383 394 404 414 427 434 446 ■ 451 482 498 507 527 541 . 561 Substance. Cadmic bromide Potassic iodate . Baric nitrate Potassio peroUprate Sodic iodide Strontis nitrate Calcic bromide . Magnesic bromide Sodic bromide . Calcic chloride . Potassio chloride Molybdio trioxide Sodic chloride . . Potassio fluoride Sodic carbonate Potassio carbonate Sodic sulphate . Calcic fluoride . Meltin, Point The following numbers will also be found of value : — Tin . Bismuth . Cadmium . 228 264 315 Lead Zinc Aluminium 571 582 593 610 628 64s 676 69s 708 719 734 759 772 789 814 834 861 902 32s 412 700 By the preceding methods, the temperature of a heated space can be ascertained at a given time, but not continuously. Several pyrometers have, however, been invented to enable large numbers of consecutive obser- vations to be taken. 342 PYKOMETEES. Gauntlett avails himself of the difference between the expansions of two rods as a means of moving a system of springs which cause the hand on a dial to rotate. For temperatures up to iooo°j one rod is of iron, the other of brass; for the range iooo°-i5oo°, the brass rod is exchanged for one of fire-clay. The Trampler pyrometer is similar in principle. A hard, but very porous rod of graphite is inserted in an iron tube, which, on exposure to heat, expands much more than does the rod. This excess of expansion is indicated by magnifying gear. Camelley and Burton claim to have invented in 1879 {though they did not then publish it) a water-current pyrometer. The arrangement is of an es±remely simple character (Fig. 220). A current of water flows from a cis- FiG. 220. tern, c, of constant level through a tube of thin copper, d e. At the place, a, where the temperature is to be determined, the tube is coiled for several turns, a b ; the effluent water is led through a small chamber, B, against the bulb of a small mercurial thermometer, d, therein contained. The difference of temperature between the inflowing and effluent water is observed, and this difference furnishes the temperature required by reference to a table pre- viously constructed from,experimen(ts at known temperatures. As uniform flow and capacity cannot possibly be maintained in a copper tube under the conditions indicated, it is obvious that the greatest possible care should be taken with the arbitrary graduation, on which the use of this instrument wholly depends. PYEOMETEES. 343 Fig. 221. Saintignon's pyrometer seems to be identical with this. Amagat also, in 1882', invented a water-current pyrometer of the same kind, in which he caused the water to flow first downwards and then upwards in the heated medium. Messrs. Boulier Brothers patented in 1883 another form of this instrument. The water is caused to circulate in a casing of thin copper, and the pipes which carry on the circulation are both led into a refrigerator, through which flows a rapid current of cold water. The temperature of the water is ascer- tained at its exit from the casing and from the refrigerator, the dif- ference between these two readings determining the temperature of the casing. It is probable that a water-cur- rent pyrometer might be made to give good indications if used for the same furnace with a steady flow of pure water — or at least of water yielding little or no deposit when heated. Siemens' electrical pyrometer dates from i860, when its inventor utilized the efiect of heat in pro- ducing increased resistance in a pro- tected copper wire, to detect heating in a telegraph cable coiled ui a ship's hold. As applied to high tempera- tures, it is constructed as follows : — Upon a cylinder of hard baked pipe- clay a double thread is cut, and in this are coiled two platinum wires, united at the lower end, whose resistance is to give the desired indication. The wire has a diameter of .01 inch, and a resistance of- about 3.6 units, per yard. The clay cylinder' occupies the lower end of an iron or platinum external case, which again is inserted in a long tube of wrought iron, employed as a handle. Connections with upper leading wires are made at the upper end of the case, there being in all a is tlie encased pyrometer, with handle and three leading wires. leading wires , b is a plan of the ciroiut Instead of employing a galvano- »°1'*^ divisions. _„„4. 4.„ „ iu -J. V V are the two voltameter branches. meter to measure the resistance y is the battery. effect, two voltameter tubes are used, s a binding screws conrjecting battery to com- in which dilute sulphuric acid is mutator. subjected to electrolysis. These are "^ '^ conductor in undivided circuit. sold withthe instrument, and are ^ fpjtlSr"^ ""• accompanied by a table, in which the temperatures corresponding with given volumes of the mixed gases are entered. Fig. 221 will assist in comprehending the nature of the arrangement. 344 PYROMETERS. FlO. 222. It will be observed that the principle of the instrument consists in com- paring the volume of mixed gases given off in one voltameter by passing an electric current through a known resistance, with the corresponding volume in a precisely similar voltameter simultaneously affected by the resistance of the heated wire. In continued practical use, the platinum undergoes some slight physical change, causing the zero indication to rise, and involving consequently a re-adjustment of the table. This is particularly noticeable after very high temperatures have been measured. Siemens' pyrometer has been used in various technical operations. The calorimetric method has been employed with considerable success as a means of pyrometry. If a body of known specific heat be raised to an unknown temperature and then immersed in an always constant volume of water, a thermometer placed in the water will give readings which are a definite function of the unknown temperature. Almost any calorimeter, if well jacketed to prevent fluctuations of temperature, will do for this pur- pose ; and the rise of temperature of the thermometer can be converted into measured temperatures by graduating the instrument with a constant weight of suitable material raised to known temperatures. Thus, Bystrbm employed a platinum ball placed inside a clay tube, which was duly exposed to the temperature required to be deter- mined ; the ball was then suddenly trans- ferred to a water calorimeter* arbitrarily graduated as above described. Siemens used a thermometer with a detached scale, so that the zero of the scale could always be set at the initial height of the mercury in the thermometer; this scale gave the unknown temperature by direct reading. Unfortunately, the scale was graduated on the assumption that the specific heat of metals does not alter with temperature. The greater part of modern pyrometry is effected by means of Weinhold's instru- ment. Fig. 222 shows a modification of it which has been found very useful in manufacturing operations. It consists of an inner vessel, A, containing a litre of water, and constructed of common tin- plate. This has two apertures — one at b, through which the pyrometric iron balls are thrown in, and another at c, in which is fixed a tin tube, protecting a thermome- ter t (reading directly to tenths centigrade); The outer vessel d also consists of tin-plate, and is closed by a lid. Cotton-wool is tightly packed between the two vessels, which are about half an inch apart. In an actual determmation, three balls of wrought iron, weighing about 20 grams apiece, are placed m a wrought-iron or clay tube, then raised to the desired temperature therein, and suddenly transferred into the water contained in the mner vessel. The aperture b is quickly closed with an india-rubber cork, and the whole well shaken. The highest reading of the thermometer is next read. It a reading has been taken just before the experiment, the rise is, of course, known. The temperature x is calculated as follows : — Let W = weight of water in pyrometer, w = weight of iron balls, C ^ water value of pyrom ter (about 20 grams), PYROMETERS. 345 then T = highest reading of calorimeter, t — initial do., s = mean specific heat of wrought iron between T and x : Inasmuch, however, as the s in this equation involves a knowledge of x, an assumption has first to be made that x has a certain value ; and the s corresponding with this is used in the calculation. The result of the calculation gives a new value of x, with which corresponds a better value of s, to be employed in a second similar calculation ; the third approximation is in general sufficiently close. This method gives results which are accurate at high temperatures to about ± io°, provided the iron balls are renewed sufficiently often. A table of values of s is subjoined. Mean Specific Heat of 'Wrought Iron Between Temperatures t^ and t^, calcidatedfrom the Formula —f- =0.105907 + 0:00003269 (<2 + <,) +0 000000022 1 59 r-S-±iL±i's±li]!'l. H-h L 2 J (Weinhold .dftM. (ier P%s. «. Chem., vol. cxlix p. 214.) Forfi= For(i = 3^8 For/,= For 734 I 490 708 9 526 746 6 663 87s 4 572 785 2 543 761 480 580 801 7 713 924 5 623 836 3 596 814 I 635 855 8 763 974 6 674 888 4 649 867 2 689 910 9 !'3 . 122023 7 725 939 5 702 920 3 744 964 370 863 072 8 776 990 6 755 973 4 799 .128019 I 912 121 9 828 .124041 7 808 .126026 5 853 073 2 961 171 410 879 093 8 861 079 6 908 128 3 .127.010 221 I 930 14s 9 9:4 132 7 962 183 4 059 271 2 982 196 450 967 185 8 .128017 238 5 109 321 3 .124033 248 I .126020 238 9 072 293 6 159 371 4 085 299 2 073 292 490 126 348 7 209 421 5 136 351 3 126 345 I 181 403 8 259 471 6 188 402 4 180 399 2 236 458 9 310 521 7 239 454 5 233 452 3 291 513 380 360 S7I 8 291 505 6 287 505 4 346 568 I 410 621 9 342 557 7 340 559 5 401 624 2 460 671 420 394 6c9 8 393 612 6 456 679 3 S'o 722 I 446 661 9 446 666 7 5i> 734 4 561 772 2 498 713 460 500 719 8 566 789 5 611 822 3 550 7<''S I 553 772 9 621 844 6 661 873 4 602 817 2 606 826 500 676 900 7 7i2 923 s 654 86.9 3 660 880 I 731 955 346 PYROMETERS. MEAN SPECinC HEAT OF WROUGHT IKON — I h For<,= 20° C. For<,= 25° a h ror«,= 20° c. Por«,= 25- C. h For«i= 20° C. Por«i= 25° C. h For«,= 20°C. 25° i. 502 ^128787 .J29011 527 .130185 •130413 552 .131611 .131840 577 .133064 •'33297 3 842 066 8 242 470 3 669 898 8 123 356 4 898 122 9 298 526 4 726 956 9 182 415 s 953 178 530 354 583 5 784 .132013 580 241 473 6 .129009 234 I 410 639 6 842 071 I 300 532 7 064 290 2 467 696 7 899 129 2 359 591 8 120 346 3 524 253 8 957 187 3 418 650 9 175 402 4 l^i 810 9 .132015 245 4 477 709 510 ^11 457 5 638 867 560 073 303 536 I 286 513 6 69s 924 I '3' 361 6 595 828 2 342 569 7 752 981 2 189 419 7 654 887 3 398 t^ 8 ^. .131038 3 247 478 8 713 946 4 454 681 9 866 09s 4 305 536 9 772 .134005 5 53? 737 540 923 152 5 364 594 S90 832 065 o 566 793 I 980 209 6 422 653 I 891 125 7 622 849 2 •131037 266 7 480 711 2 950 18S 8 678 905 3 095 324 8 538 769 3 •134009 244 9 734 961 4 152 381 9 596 827 4 o6g 304 520 790 .130018 S 209 438 570 655 886 128 364 I 846 074 6 267 496 I 713 944 6 188 ' 423 2 903 131 7 324 553 2 771 .133003 7 247 4S3 3 959 187 8 381 610 3 830 062 8 307 543 4 .130016 244 9 438 667 4 888 121 9 366 603 S 072 300 5SO 496 725 5 947 180 6 129 357 I 553 782 6 ■133005 238 / Forti= For«i= For S12 7 923 171 620 108 347 704 945 2 330 575 8 987 23s I 168 407 7 76s .138006 3 393 638 9 .141050 299 2 229 468 8 827 069 4 455 701 700 114 362 3 289 529 9 887 130 5 S'8 764 4 350 589 650 950 193 6 582 828 5 410 650 I .138013 256 7 646 892 Amongst other means of measuring temperatures may be mentioned the well-known thermometer of Berthelot, which consists of a simple upright reservoir of glass, closed by a narrow tube, bent twice at right angles, and terminating in a U gauge containing mercury. The gauge carries a scale empirically graduated by placing the air reservoir in the vapour of liquids at known boiling point, the expansion of the air altering the level of the mercury PYEOMETEES. 347 in the gauge. Recknagel.and Mills, however, have shown that in instruments of this kind the zero cannot probably remain constant for more than a day, on account of entry of air into the reservoir against the mercurial pressure. This thermometer, therefore, is not adapted for use in works. The tension principle has also been proposed by Messrs. Schiiffer and Budenberg. Their instruments consist of extremely strong reservoirs, con- taining ether, water, or mercury, according to the conditions under which the pyrometer is to be employed. The reservoirs are jointed to common Bourdon manometers, filled with the same liquids, and consequently really register tensions. In this case, everything depends on the tightness of the joint, and the impermeability of the metallic envelope to vapour of the liquid at a high temperature. In actual trial for charcoal kilns and other purposes, these instruments have, as might be expected, proved leaky and untrustworthy ; but it is probable that for the lower part of their scale they would show more steady and accurate indications. The pyrometers chiefly used for measuring the heat of the hot blast con- sist of strips of metal soldered together and bent into a helical form; one end of the helix is connected with a hand running over a dial; the other is attached to the wall of a box. A change of temperature causes the helix to coil or uncoil, as the case may be, and thus efiects a movement of the hand over the dial. < Combined strips of brass and steel (Kahl's instrument) wiU measure temperatures up to 440° C. The dial is graduated in the lower part of its scale by comparison with a mercurial thermometer, and in the upper by inference from the lower. A new pyrometer for measuring hot blast .temperatures, which has stood the test of continuous work for over two years in Messrs. Addie's Langloan Ironworks at Coatbridge, N.B., has been described tinder the name of Frew's pyrometer. It makes use of the expansion of the air due to heat to move a coloured liquid over a scale properly graduated. It is an ingenious form of air. thermometer,* with some modifications, which the description and illustration published in " Engineering " of January 8, 1886, will make plain. References may be made to the following papers, which contain sugges- tions of interest — viz., " On a New Form of Gas Thermometer," by G. Beilby ("Jour. Soc. Chem. Ind.," 1885, p. 40), and " Description of an Improved Thermometer for taking High Temperatures," by J. Murrie {Ibid., pp. 45, 189, 65s); Crookes and Rohrig's "Metallurgy," vol. iii. pp. 320-347; " On a New Mode of measuring High Temperatures," by John Wilson (" Proc. Inst. Mech. Engineers," 1852, p. 53). See, also, "Pyrometers" in "Jour. Iron and Steel Inst.," vols. i. 1884, pp. 195, 196, 240-242; i. 1885, p. 325 ; i. 1886, p. 207. None of the earlier instruments or methods for the direct estimation of high degrees of temperature ai'e of any real practical value, and we are consequently referred, in general, to the elementary composition of com- bustibles, in order to estimate their pyrometrical heating values approxi- matively by calculation. The entire amount of heat developed during the combustion of a com- bustible must necessarily be transferred to the products of combustion. The absolute heating power of the different combustibles has been expressed above by the heat which they respectively communicate to a given amount of water ; if this known amount of heat be transferred from water to the products of combustion, we must obviously obtain the mean temperature of the combustion, or the pyrometrical value of the fuel consumed. The specific heat of water, in reference to that of the gases generated, forming an important element in the calculation. • A description of a delicate instrument of this kind is given in Zeit. physikal, Chem,, vol. i. pp. 79, 97 (abstracted in " Journ. Cbem. Soc," toI. liv. p. 331). 348 PYROMETEICAL HEATING POWER. The following example, in which it is j;rop3sed to estimate the pyro- metrical heating power of carbon by calculation will illustrate this method and in order to complicate the calculation as little as possible, the combus- tion is assumed to take place in pure oxygen gas. Carbon requires 2| times its weight of oxygen for complete conversion into carbonic acid. The absolute heating power is consequently according to formula (p. 336) 3000.2! = 8000. The heat generated during the com- bustion of I part of carbon will, therefore, raise the temperature of 8000 parts of water 1° of the centigrade thermometer, or will heat i part of water from o" to 8000° C, or will raise 3| parts of water from 0° C. to — g-= 2182° C. During the combustion of i part of carbon 3I parts of car- 3s _ bonic acid are produced, to which the entire amount of heat generated during the combustion, except the radiant heat, is transferred. If, therefore, the spe- cific heat of carbonic acid were identical with that of water, the temperature of the gas would be 2182° C. ; but the specific heat of carbonic acid as com- pared with water as unity is = 0.2210; the temperature of the carbonic acid produced by the combustion will consequently be in the inverse ratio, or =9873° C The pyrometrical heating' power of carbon burning in 0.2210 oxygen gas is therefore 9873° C. A general formula may be constructed in a similar manner for the pyrometrical heating power of any combustible. If represent the amount of oxygen with which i part of a combustible com- bines on burning and s the specific heat of the products of combustion, its pyrometrical heating power will be expressed by or P= tooo, X- when is made - as explained at ■^ (a + n)s a '^ a former page. The pyrometrical heating power of a simple combustible body is there- fore expressed by its absolute heating power in heat units divided by the product of the relative weight of its combustion-product and its specific heat. This formula has reference to a simple combustible body burning in oxygen gas. In order to establish similar formulae for compound combustible bodies, the following physical law must be known : When A, B, C, D, represent difierent quantities of the same fluid, possessing temperatures corresponding to t, t', t", t'" degrees C, the mean temperature of the mixture of all these fluids will be At + Bt' + Ci" + nt'" ,p. — TrBiir^D ' ^"' if these fluids are of different chemical constitution, and consequently have different specific heats, then when s, /, s", «'", express their corresponding capacities for heat, the mean temperature of the mixture will be expressed by Ast + Bs't' + Cs"t" + Ds"'t"' + . . . ,^,. As + B8' + Cs" + Ds"' + ... ^ With the aid of this formula, the problem in question may be solved in the following manner r Let the fuel consist of a, b, c, d, parts by weight of the difi'erent PYROMETRICAL HEATINQ POWER. 349 combustible bodies. Then retaining the mode of expression employed on a former occasion — By the combustion of: The product of combustion will be obtained a a{i+0) =A b b(i + 0') =B c c(i + C»")=C d d{i+0"')=D &c. (fee. The degree of temperature produced by the combustion of a, h, c, d, or the temperature of the products of combustion (A, B, C, D) are easily obtained by means of the formula (5) By the combustion of: Degree of temperature obtained. 3000 ^^^ =t a 3000 =«' (1 + 0') s' 0" ' ^ {i + 0")s" 3ooo^^,=r (fee. (fee. If these values for A, B, C, and B, and for t, t', t", V", are now inserted in the formula R', we obtain ; and when is made = - , = -^, 0" = — . . . P y a- + b—\c—^d — + . . . . The pyrometrical heating power of a compound combustible body is therefore expressed by its absolute heating effect in units of heat divided by the sum of the relative weights of all the products of combustion of its constituents, each of these being multiplied by its corresponding specific heat. If the combustion takes place in atmospheric air instead of in oxygen, the effect is very much lessened, as the whole of the nitrogen in the air which accompanies the oxygen consumed is necessarily mixed with the products of combustion. It therefore becomes necessary to ascertain what proportion of nitrogen is left for each proportion of oxygen consumed, and likewise what mean temperature will result from the mixture of that amount of nitrogen which, without any serious error, we may assume to be at o" C, with the other products of combustion. When carbon burns in oxygen gas, the temperature of the product of combustion was calculated at 9873° C. Atmospheric air is composed in 100 parts of 23.1 oxygen to 76.9 nitrogen ; to each part of oxygen there are therefore ?— ^ = 3.33 parts of nitrogen. One part of carbon consumes in 23.1 ■^ 350 PYEOMETEICAL HEATINO POWER. burning to carbonic acid 2| parts of oxygen, there will consequently be ^i • 3-33 = 8.88 parts of nitrogen liberated when i part of carbon is burned, and this nitrogen will be mixed with the carbonic acid, which if alone would have acquired the temperature of 9873° C. The specific heat of carbonic acid is = 0.2210, and that of nitrogen = 0.2754. According to formula (E') the temperature must therefore be expressed by 38. X 9873 X 0.2210 + 8.88 X o X 0.2754 ^ ^ go ^ 3| X 0.2210 + 8.88 X 0.2754 ^ The general formula for the pyrometrical heating pdwer obtained in this manner will therefore be expressed by : F — 3000J (i + 0)8 + 0.917 or P = 3000 , r (a + »»)« + 0.917 n In order to obtain a similar general formula for the combustion of a compound combustible body in atmospheric air, the fbllowing physical law must be adverted to. When A B C D . . . . denote different quantities of fluids, all possessing the same temperature *, but different capacities for heat s s' s" s'" . . . ., and to these already mixed fluids a fluid Q is added, the temperature of which = T, and its specific heat = o-, the me-an temperature of the whole will be expressed by : (As + Ba' + Cs" + I)s"'+. . . .)t + Q .a.T ,„„. A8 + Bs' + Gs" + Ds"'+ + Q7Z ^ ' The application of this formula will be readily understood. ABC B .... represent the different products of combustion of the constituents ah cd . . of the fuel ; s if s" s" .... the specific heat of the yiroducts of combustion ; t is the temperature produced by the ■ combustion of the fuel in oxygen, therefore = P in the formula (6) ; Q = the quantity of nitrogen separated from the air with the oxygen consumed ; P = the specific heat of the nitrogen, and T the original temperature of the nitrogen assumed at 0° 0. There must consequently be interpolated in the formula (Sf') : A = a{t+0),B = {i+0'), C = c{i+0"), 8 — S» 8 ^— o • o ^— Q f > ■ ■ > aO + bO' + cO"+ t =- a {i +0) s + b {I + 0') s' + c {i +0") s" + Q = 3-33 {«0 + bO'+cO" +....) a =0.2754 T=0 With these substitutions we obtain : p=,ooo aO + 6Q' + cO" + rfO"'+ . . . (8„) ^ [a(i + 0> + 6(i + 0')s' + c(i + 0")s"+ . . .] + o.9i7[aO+60'+cO"+ . . .1 or when = -, 0' = — , 0" = —, &c., &c. a /3 y o a "= 3000 - a- + o— + c — +0 — + . . . [„(l + 3, + .(:+0. + .(:+.»_y+...] + o.9:7[„^+.|H-£+...] (86) PYEOMETEICAL HEATINO POWER. 3SI In these formulse, which will be subsequently applied : abed... denote the relative proportions by weight of the different combustible bodies of which fuel is composed, the total quantity being = i. 0' 0" . . . . denote the relative quantities of oxygen with which those proportions combine during combustion. nn' n" . . . . denote the number of equivalents of oxygen with which I equivalent of the different combustible substances combine. a p y . ... are the atomic weights of these bodies, the atomic weight of oxygen being = i. s s' s" . . . denote the specific heats of the products of combustion of the bodies consumed. The following table contains the pyrometrical heating powers of several simple and compound bodies calculated according to these formulae, both for jombustion in pure oxygen and in atmospheric air. Pyrometrical Heating Power expressed in o° C. In Oxygen. In Atmo- spheric Air. Carbon Vegetable oil Ethylene . Ether (C,H,0) . Marsh gas . Alcohol* (C^HjO, HO) Hydrogen . 9873° 6024 5793 5484- 4800 4521 3172 2458° 2122 2090 2049 I94S 1910 161 1 Absolute accuracy has not been attempted in calculating these heating values, several circumstances which influence the result more or less having been neglected. Amongst these may be noticed that, for the co-efficients s s' s"s the values which have been introduced have reference to the specific heate of these gases at the ordinary temperature of the air. The co-efficients are consequently too small, the capacities increasing with the temperature ; they should have been calculated for the temperature of combustion. As these only occur in the denominators of the formulse, the pyrometrical heating powers will be somewhat too high. Again, the combustibles before entering into combustion aU require to be heated to a certain extent. Thus, oil for instance requires a temperature of 315° C. at its burning surface, at which temperature it is decomposed into gaseous products ; cold oil does not burn, but the gases do so which are generated at a temperature of 315°, which temperature they consequently possess, and this will have a corresponding effect in raising the pyrometrical value. This cause can exert but little influence on the calculated heating effect of ether and alcohol, as these liquids boil at comparatively low temperatures, and none whatever on the combus- tible gases hydrogen and maish gas. In the case of carbon, however, it is the red-hot carbon alone which burns. The two former of these causes can exert but little influence on the pyrometrical value of fuel, but the latter in- creases to some extent the temperature of combustion of carbon and oil. Again, the prime unit or factor 3,000 is not improbably too high, and would be advantageously exchanged for the lower value 2,800. Although not absolutely accurate, the following general conclusions may be drawn from the results collated in the table above. I. The pyrometrical heating power of carbon is greater, that of hydrogen smaller, than that of any one of the other combustibles. The combustion- * In calculating the pyrometrical effect of alcohol, it has been taken into consideration that if contains 19.37 P^"" cent, of water ready formed, the evaporation of which diminishes its heat- ing effect. The latent heat of the vapour of water has not been taken into account. 352 PYEOMETRICAL HEATING POWER. temperature of carbon is more than 3 times as great as that of hydrogen. The inflammable fuels must therefore all have a lower pyrometrical heating power than those which burn without ilame, or than more or less pure carbon. 2. The pyrometrical heating power of different combustible bodies whose property of combustibility depends on the carbon and hydrogen they contain is greater in proportion to the amount of carbon which they contain. 3. The difference between the pyrometrical heating powers of different fuels is very much more considerable when the combustion takes place in oxygen gas than when it occurs in the air. Thus between carbon and hydrogen, when burnt in oxygen gas, there is a difference of 6000° C, whilst in atmospheric air the difference does not exceed 800° C. It appears anomalous that the pyrometrical heating power of carbon should be 3 times as great as that of hydrogen, while the absolute heating powers of the two substances are precisely in an opposite ratio. The cause of this lies partly in the specific heat of aqueous vapour being nearly 4 times as great as that of carbonic acid, and more especially in the circumstance that I part of hydrogen produces in burning 9 parts of aqueous vapour, while I part of carbon yields only 3| parts of carbonic acid. It must also be noticed that the combustion-temperatures stated in the table above have reference to that locality either in immediate contact with the fuel or in the flame, where the actual combustion takes place. Un- favourable circumstances may confine this to a very limited compass, and the pyrometrical effect will apparently be diminished in proportion. In the preceding calculations, the heating power has been expressed by the quantity of water heated to 1° C. by the heat evolved during the com- bustion of I part of the combustible ; but, practically, where fuel is employed for other purposes than that of raising the temperature of water, as in all metallurgical operations, the effect is very much diminished. In the appar ratus employed by Rumford and others for estimating the absolute heating power, the products of combustion escape at temperatures very little above that of the water heated. The steam produced by the combustion of the hydrogen in the combustible is condensed into the state of water, and the large amount of heat that was latent in the steam is, therefore, expended in raising the number denoting its heating power. When the combustible is employed in the furnace for producing much' higher temperatures than that of boiling water, the water produced by combustion escapes in the state of steam, carrying with it its latent heat, and diminishing by so much the heat- ing effect of the fuel. The formulae above given will therefore require modi- fication. It has been proved by experiment that the quantity of heat required to evaporate i part of water from 100° C. is very nearly 5 J times as great as the quantity required to raise i part of water from 0° to 100° C. In cor- recting the formula for the absolute heating effect of a combustible, the total quantity of hygroscopic and chemically combined water, as well as that produced during combustion must therefore be multiplied by s|.ioo = 550, and the product subtracted from the previously ascertained number. If the latter be denoted by A, the corrected number by a, and the total amount of •water by W, we obtain : a = ^ - 550 r. (9) If a- denote the corrected and iS" the previously calculated specific heating effect, and if n denote the corrected and P the originally calculated pyro- metrical heating effect, we obtain the following proportions : S : or -■- A to a F: TT = A to a RELATIVE VALUE OF FUEL. 353 whence a = -- S A (lo) 2^ (") In the following table (taken from Scheerer's Metallurgie) the dif- ferent heating effects of combustibles which contain water or form water during combustion, are calculated with the corrections. In the column of absolute heating eiTects, the heating effect of carbon is taken as unity. The numbers for the specific heating effects are the products of the absolute heating effects and the respective specific qualities of the combustibles. The pyrometrical effects are expressed in degrees of the centi- grade thermometer. Dulong's determinations of the heating power of hydrogen, carbonic oxide, marsh gas, and olefiant gas have been adopted as the more correct, and the numbers hitherto obtained by Welter's law are quite inadequate to account for the effects produced in practice. Woi.d. (with 20 per cent, hygvoscopic (with ID per cent. hygroBCopic Air-dried wood moisture) . Kiln-dried wood moisture) . Kiln-diied wood (without hygroscopic moisture) White beech* Oak Oalc . . Ash Maple, birch, bird-cherry .... Eed beech, horse chestnut, elm, white-thorn . Scotch fir, alder ....... Sallow Willow . . .... Spruce fir, silver fir, larch . ... Lime, aspen ....... Black poplar, Italian poplar Turf.— Peat. Imperfectly air-dried turf (with 30 per cent, hygro- scopic water and 10 per cent, of ash) . Best air-dried tnrf (25 per cent, moisture and no ash]! Kiln-dried turf (no moiNture and 15 per cent, ash) Best kiln-diied turf (witliout njoisture and ash) Lignita. — Brown coal. Air-dried, fibrous lignite (20 per cent, moistiu'e and no ash) . The same (20 per cent, moisture and 10 per cent, ashi Air-diied, earthy lignite (20 per cent, moisture and no ash) . . \ . The pame (20 per cent, moisture and 10 per cent, ash) Air-dried lignite, conchoidal fracture (20 per cent. moisture and no ash) . ... Air-dried lignite, conchoidal fracture (20 per cent. moisture and 10 per cent, ash) .... Kiln-dried, fibrous lignite (20 per cent, moisture and no ash) ........ The same (20 per cent, moisture and lopercent. ash) Abpoluie. 0.36 0.41 0.47 0.37 0.47 0-5S 0.65 0.48 043 0.61 o-SS 0.69 0.62 0.61 o-SS Heating Ettiiut, Specific. 0.28 0.26 0.25 0.24 0.23 0.21 0.20 o. 19 0.18 0.17 0.16 0.14 0.5S 0.79 0.83 Pyrome- trical. 1575 167s 1750 I57S 1750 1 975 2000 1800 1975 2050 2025 , .' The sjjecific heating effects of all these woods are calculated from specimens in an air. dried condition. «." ~u A A 354 EELATIVE VALUE OF FUEL. HEATINO EFFECT OP FUELS- Heating Effect. Absolute. ^ Speeiflo. Pyrome- trioiU. Lignite.— Brown coal — {continued). Kiln-diied earthy lignite (20 per cent, moisture and no ash) 0.76 — 2125 The same (20 per cent, moisture and 10 per cent, ash) 0.69 — Kild-dried conchoidal lignite (20 per cent, moisture and no ash) o.8'5 — 2200 The same (20 per cent, moisture and 10 percent, ash) 0.76 — Coal. Sand coal { 0.79 1.06 2200 CalSiycoil ^5 P^"" '''°*- ™'''t""'^ *°'J S per cent, ash) 0.89 1 0.93 I 0.96 0.16 I.17 2250 2300 Anthracite , 1.44 2350 Wood charcoal. Air-dried black charcoal (12 per cent, moisture and 3 per cent, ash) 0.97 — 2450 Perfectly dry ditto (3 per cent, of ash) . 0.84 — 2350 Air-dried red charcoal (10 per cent, moisture, 14 per cent, ash) . . .... 0.72 — 2200 0.64 — 2100 , Birch ... — 0.20 , 1 Ash, wild service . — 0.19 9 Bed beech, white beech, elm . Bed fir Maple ... No moisture r and 3 per r.ATit. nf ash_ < 0.18 0.17 0.16 — cS Oak, pear-tree . . . j Alder . . — 0.IS — — 0.13 ^ Lime . . .J " — O.IO — Feat charcoal. Worst description of air-dried peat charcoal (10 per cent, moisture and 56 per cent, ash) . 0.8s — 2050 Best air-dried peat charcoal (10 per cent, moisttu'e, 4 per cent, ash) . .... 0.83 — 2350 Coke. Good coke (10 per cent, moisture and 5 per cent, ash) 0.84 2350 Best ditto (5 per cent, moisture and 3 per cent, ash) Ditto (no moisture and 3 per cent, ash) 0.92 — 2400 0.97 — 2450 Sand-coke f — 0.46 Sinter-coke (no moisture, S per cent, ash) — 0.41 — Oaking-cokej . — 0-33 — Gaseous combustibles. (J'urnace gases.) Gases from wood charcoal O.I 08 0.000140 1675 Ditto „ „ „ ... 0.080 0.000104 1450 Gases from coke . 0.107 0.000139 1750 Gases from coal 0.205 000267 1850 (Generator gases.) Gases fi-om wood charcoal .... 0.115 0.000150 1775 Gas from wood 0.136 0.000177 1850 Ditto „ „ 0.124 0.000161 IS7S Gas from turf .... 0.092 0.000120 1525 Gas from coke .... 0.1 10 0.000143 I77S EELATIVE VALUE OP FUEL. A summary view of these results is given in the following table : 355 Heating Effect. Absolute. Specific. Pyrometrical. Gaseous combustibles 0.08—0.205 0. 000 1 — 0. 0002 7 1450— 1850 Wood 36—0.47 0.14 — 0.28 •575-1750 Turf. ... . . 0.37—0.65 — 1575 — 2000 Lignite 0.43 — 0.85 — . 1800 — 2200 Coal (5 per cent, moistuve and 5 per cent, ash) 0.79 — 0.96 1.06 — 1.44 2200—2350 Peat charcoal . ... 0.83—0.85 — 2050-2350 Wood charcoal .... 0.64 — 0.97 0.10—0.20 2100 — 2450 Coke (containing not above 5 per cent. ash) 0.84 — 0.97 0.33 — 0.46 2350—2450 The calculations from which these numbers result have been made on the assumption that the combustibles are entirely consumed, which certainly never occurs in practice, and the numbers must, therefore, be practically somewhat too high ; they are likewise supposed to burn during a very short space of time, and give out during each successive period of that time, the same amount of heat, which we also know not to be practically the case — the process of dry distillation and the combustion of the inflammable gases always preceding the more intense heat of the glowing charcoai. Combustibles con- taining a large amount of ash are prevented from burning completely, by the impediment the ash offers to the draught, and to such as burn with a very smoky flame it is difiicult to afford sufficient air to prevent a loss from uncon- sumed carbon. The effect of the gaseous combustibles is reduced below the calculated number by a certain amount of aqueous vapour, nitrogen and carbbnic acid which they contain. This affects the gases evolved from wood and coal more than those from charred combustibles, and is in some measure compensated by the high temperature possessed by the combustibles before ignition. Welter's law has been conveniently applied to calculate the theoretical heating power of combustibles of which the composition is accurately known. Recent experiments, however, conducted with every precaution to avoid error, by Messrs. Favre and Silbermann, by Grassi, Andrews, Thomsen and others, have proved that the heat evolved by a given weight of oxygen is not the same when different substances enter into combination with it and are consumed. The absolute heating power of carbon, in being converted into carbonic acid, was found by Grassi between 7,632 and 7,801, by Favre and Silbermann at 8,086, by Andrews at 7,881, the older experimenters had fixed it at 7,800 ; in round numbers, it' may therefore stiQ be assumed at 8,000. When carbon burns to form carlsonic oxide, the heating effect was estimated by Grassi at 2,480. The following are the results of different experimentalists with reference to the absolute heating effect of hydrogen. 26,640 Despretz, Lavoisier, and Clement. 34,800 Dulong. 34,188 Favre and Silbermann. 34,656 Grassi. 33,808 Andrews. The first number would indicate an amount of heat treble that afforded by carbon, and this has generally been assumed as the absolute heating effect of hydrogen. The last four results, which corroborate each other, and which have been obtained by more accurate methods, would increase the A A 2 3S6 EELATIVE VALUE OF FUEL. absolute heating effect of hydrogen to nearly 4J times that of carbon, or 36,000, which may be taken in round numbers as the actual effect. The absolute heating effects of carbonic oxide, marsh gas, and olefiant gas have not been definitively settled even by the recent careful experi- ments ; the results varying as follows : 12,403 — 2,466 Dulong, Favre and Silbermann. 2,431 Andrews. 1,857 — 1)876 (sp. gr. of cavb. oxide taken at 0.9678) Ualton and Grassi. 1,710 according to Welter's theory. 6,375 Dalton. 13,223 (sp. gr. 0.5589) Dulong. 13,108 Andrews. 13,158 Favre and Silbermann. 10,945 Grassi. 1 12,000 according to Welter's tbuory. ' 6,600 Dalton. 12,172 (sp. gr. 0.9675) Dulong. 11,942 Andrews. 11,900 Favre and Silbermann. 8,557 Grassi. 10,290 according to Welter's theory. Marsh gas. Olefiant gas. When, therefore, as is probable from these results, the absolute heating power of carbon is taken in round numbers = 8,000, that of hydrogen = 36,000, that of carbonic oxide = 2,404 — 2,466 or = 1,857 — 1,876, that of marsh gas = 13,158 — 13,223, and that of olefiant gas= 11,900 — 12,172, and when the quantity of heat produced by the union of i part of oxygen with carbon in forming carbonic acid is taken as= i, we then obtain the following relative heating powers : 1 Part of Oxygen produces Relative Heating in combining with : Power. Carbon ........ I. CO Hydrogen . . .1.50 Carbonic oxide . . . 1.44 or 1. 10 Marsh gas . . . . . . . 1. 10 Olefiant gHS . . . . . . . 1.17 These numbers, which are the co-efiicients of intensity, show how far Welter's law deviates from the results of experiments. The formula for calculating the heating power of a combustible according to Welter's law will therefore require modification in order to obtain the actual eff'ect. The requisite alteration applies chiefly to the co-efficients of intensity, and those for carbon and hydrogen being diff'erent from those for carbonic oxide, marsh gas, &c., it is desirable to construct separate formulae for the two classes of combustibles, the solid and gaseous. There is, however, much force in the point ■ raised by Gr. Bethke and F. W. Liirmann (in their paper on " Welter's Law and the Latent Heat of the Gasification of Carbon," in the Journal of the Society of German Engineers, 1885) to the effect that those who have condemned Welter's law as incorrect have not considered the amount of heat which is rendered latent when carbon passes from the solid to the gaseous state. They give a demonstra- tion, from which we quote, that the law holds good whether hydrogen or carbon be burned with oxygen, and they hazard the supposition that it may hold good for all other chemical combinations of oxygen. They remark that " when one part by weight of hydrogen combines with eight parts by weight of oxygen to form water, one part by weight of oxygen in this case produces 33,600 ,, , . ^^-' — = 4,200 thermal units. o " Again, one part by weight of carbon monoxide combines with ^ parts by RELATIVE VALUE OF FUEL. 357 weight of oxygen to form carbon dioxide, and in this case one part by weight of oxygen produces -^- = 4,200 thermal units, or the same quantity of heat. T " Similarly it happens that one part by weight of oxygen by burning from carbon to carbon monoxide produces -^-j — = 1,800 thermal units, and by burning from carbon monoxide to dioxide ' ^ = 3,000 thermal units. 'S " These last numbers are quite right, for the standard values for the heats of combustion have been determined by many exact experiments, but up till now no one has taken into consideration that by the combustion of solid carbon to the gaseous compounds carbon monoxide and dioxide a certain quantity of heat must be rendered latent which does not appear in the com- bustion experiments, and consequently the actual value seems up to the present time not to have been arrived at.* This latent heat of gasification of carbon can, however, be calculated as follows : — " Let us consider the combustion of carbon monoxide, which is a gaseous body containing carbon in the gaseous state. It consists of j parts by weight of carbon and j parts by weight of oxygen. This latter of course con- tributes nothing to the heat of combustion when more oxygen is added. The fresh supply of oxygen attacks the carbon which exists as monoxide, so that on burning carbon monoxide to dioxide |- parts by weight of oxygen com- bine with f parts by weight of gaseous carbon, and produce thereby a quan- tity of heat equal to 2,400 thermal units. This makes for one part by weight of carbon in the gaseous form, -^— = 5,600 thermal units. Experiments on T combustion have shown that one part by weight of solid carbon on com- bustion with oxygen to carbon monoxide yields 2,400 thermal units. The difference therefore is 5,600—2,400 = 3,200 thermal units, which is the quantity of heat rendered latent in converting the carbon from the solid to the gaseous state. " Taking this into consideration in calculating the heat of combustion of carbon, it follows that one part by weight of soKd carbon produces on burn- ing to carbon monoxide gas 5,600 thermal units, of which 3,200 are latent and 2,400 sensible. Moreover, one part by weight of solid carbon on burning to carbon dioxide produces 11,200 thermal units, of which 3,200 are latent and 8,000 sensible. In both cases it appears that the oxygen in the com- bustion produces 4,200 thermal units as in the case of the gaseous bodies carbon monoxide and hydrogen. Thus by the combustion of carbon to carbon monoxide \ =4,200 thermal units, and by the combustion of carbon to carbon dioxide — \ — — 4,200 thermal units are obtained. 3^ " Welter's law thus holds good throughout for combustible bodies in the gaseous state. " When burning solid bodies to the gaseous form, we must introduce into the calculation the latent heat of gasification. " Welter's law also admits of being put in the following form which gives a simple relation between the heats of combustion of different bodies : — On combustion with oxygen every simple or compound body develops a quantity of heat = 33,600 thermal units (the heat of combustion of hydrogen to water) * These authors seem to have overlooked the able and exhaustive paper on Combustion published by M. E. Minary in Publication Industrielle des Machima mlils a apuarnls (Paris, 1868), vol. 18. M. Minary enters fully into the question o£ the latent heat of the gasification of ■Oa'bon in that paper. 3S8 RELATIVE VALUE OF FUEL. divided by the atomic weight of the body and multiplied by the number of parts of oxygen which produce the combustion — thus "i "i 600 Hj + = ^^ — = 33,600 thermal units C + = ^3^°°= 5,600 „ „ C + 20 = 'i^;— X 2=11,200 „ „ CO + = = 2,400 thermal units." 14 These authors conclude by saying that they purpose instituting an inquiry into the question whether Welter's law holds good for every chemical combination. FOEMtTL.S! FOB THE ABSOLtJTB HEATIBTO EFFECT. a. For solid fuels, containing carbon, hydrogen, nitrogen, water and ash. , The heating effect of a fuel containing by weight c parts of carbon, h of hydrogen, w water chemically combined, and w' of hygroscopic water may be calculated from the following formula, admitting that i part of carbon requires 2| = 2.67 parts of oxygen for complete combustion, and I part of hydrogen requires 8 of oxygen. j1= 3,000 [c. 2.67 + i.S . A.8]-5So [9 . A + to + w'] (12) The above formula gives the heating power in units of heat : in order to make a comparison with that ef carbon as unity, the result must be divided by 8,000, the absolute heating effect of carbon, the negative element in the formula having reference to the correction for the latent heat of aqueous vapour. 6. For gaseous combustibles containing carbonic oxide, hydrogen, marsh gas, defiant gas, nitrogen, carbonic acid and aqueous vapour. The heating power of a fuel of this description containing by weight k parts of carbonic oxide, h of hydrogen, g of marsh gas, o of defiant gas, n of nitrogen, k carbonic acid and w aqueous vapour will be obtained by means of the following formula, admitting that i part of carbonic oxide combines with 0.57 parts of oxygen; i part of hydrogen with 8 of oxygen; i part of marsh gas with 4 parts of oxygen ; i part of defiant gas with 3.43 of oxygen; and that i part of marsh gas in burning produces 2.25 parts of water, and i part of defiant gas 1.29 parts of water : (13) A = 3,000 [x .k.o . 57 + 1. 5. A. 8+1. 1 -g -4 + + 1.17 .o-SASl-SSolff ■h+ 2-25. g+i.2g.o.+ w]. The co-efficient of intensity for carbonic oxide is represented by x in the formula, as it still remains questionable whether Jt is 1.44 or i.i. The corrected formidcB for the specific heating effect are obtained from the above by multiplying the results into the respective specific gravities. The fornvtdcB for the pyrometric heating effect are easily deduced from those for the absolute effect, the latter being made = ^ we obtain a. For solid combustibles : p_ A / \ 3.67. cs + (fl'./s. + 10 + !c'y + [» + 3. 33(2.67.0. + 8 . A)]*" + o . «'" In this formula, s expresses the specific heat of carbonic acid, s' the specific heat of aqueous "vapour, s" the specific heat of nitrogen, and *'" the specific heat of the ash. The nitrogen which may possibly be contained in the fuel is represented by n and the ash by a. RELATIVE VALUE OP FUEL. 359 For gaseous fiiels, the iollov/ing formula is obtained, when the absolute heating effect is =" ^, and i part of carbonic oxide is converted into 1.57 parts of carbonic acid; i part of marsh gas into 2.75 parts of carbonic acid and 2.25 of water; and i part of olefiant gas gives 3.14 parts of car- bonic acid and 1.29 parts of water : ^ (IS) p= 2 {K)s + S (w) s' + 2 {n) s" S {K) = K+ I. S7 . A+2.75 .9-4-3.14. 2 (w) = iv + g . h+ 2.25 . g+ 1.29 . o S ln)=n+s-33 (" • 57 • ■^ + 8. /i+ 4- 9' + 3-43'0)- The letters in the formula apply to the same magnitudes as in the previous formula for the absolute heating effect, with the exceptions of s, s' and s", which denote respectively the capacities for heat of carbonic acid, aqueous vapour and nitrogen. The formulffi (14) and (15) are calculated for combustion occurring in atmospheric air ; if the combustion takes place in oxygen gas, the magnitude multiplied by s" in the denominator of the fraction has only to be made = o in order to obtain the corresponding heating effect. The pyrometrical heating effects of the following substances, calculated by R. Bunsen* from similar formulse, are expressed as follows : In Oxygen. In Air. Carbon 9,873° c. 17,803.4° F-' 2,458° C. 4,456.4° F. Carbonic oxide 7,067 12,752.6 3,042 5,507.6 Olefiant gas . 9,187 16,568.6 1 5-4 1 3 9,775-4 Marsh gas 7,851 14,103.8 5,329 9,624 2 Hydrogen 8,061 14,541.8 ; 3,259 5,898.2 Bunsen remarks that " these numbers represent the temperatures which the various gases attain on combustion with exactly the requisite amount of oxygen or air, supposing that the inflamed gases can freely expand, as is the case in an open flame. If, on the contrary, the combustion occurs in a closed space, under circumstances in which the volume, and not the pressure of the gas, remains constant, the temperature of the combustion will be totally different." If the determinations of Dulong, Favre and Silbermann for the absolute heating effect of carbonic oxide be correct, the remarkable and apparently paradoxical fact would be established, that carbonic oxide burning in atmo- spheric air produces a greater intensity of heat than carbon itself. The circumstance is however explained, not only by the high absolute heating power of cai'bonic oxide, but by the lesser amount of gaseous products of combustion that result ; i part by weight of carbonic oxide producing only 2.47 parts of gaseous products, whilst i part of carbon produces 12.57 pat'ts when the nitrogen separated from the air is included. The pyrometric heating effect of carbon in being converted into carbonic oxide may be calculated from the absolute heating effect of that gas, as estimated by Favre and Silbermann, which amounted to 2480 : then p ?l485 T,TO°r ^- 2i 0.288' + 3i . li . 0.275 ~ '^ I part of carbon combines with r^rd parts of oxygen to form 2 Jrd parts of carbonic oxide; the specific heat of this gas is 0.288, that of nitrogen being 0.275. The specific heats introduced above are those observed by De la Eoche » " Gasometry," p. 242, edition 1857. 36o RELATIVE VALUE OF FUEL. and Berard. Suermann, Apjohn and others have arrived at different numbers for the specific heats of several gases, which, if adopted, will slightly alter the results. The values of different fuels, as ascertained approximately by Berthier's plan by himself and others, are given in the following tables (I.-VIII.). Dried in the Or- dinary Manner. Containing g per Cent. Water. Perfectly Dried. Berthier. Winkler. Schodler and Petersen. 1 lbs. of lbs. of Oxyg-en required for the Complete CombUK- tion of lib. lbs. of Quantity of Air Species of Wood. lbs. of Lead re- duced by I lb. of Wood. Water which 1 lb. can heat from 0° to 100° C. lbs. of Ijead re- duced by 1 lb. of Wood. Wafer heated by 1 lb. from 0° to 100° C. Water conse- rcS from 0° to 100° 0. at 19° C. required to consume completely i lb. in lbs. 1 in C. F. Hessian. I part Oak wood I2.S 28. s 14.05 31.82 I-3S8 39.82 5-83 154-4 , Ash 14.96 33-89 I -356 39-76 5.82 154-2 , Sycamore „ I3-I 29.7 14.16 32.07 1-394 40.8s 5.98 148.4 , Beech 137 31.0 14.00 31-71 1.346 39-44 5-78 152.9 , Birch 14 31-7 14.08 31.90 1356 39-73 582 153-0 , Elm „ — 14.50 32.84 1.418 41-55 6.08 101.1 , P'iplar — . — 13.04 29.54 1-390 40.72 5-96 1579 , Lime-tree,, — — 14.48 32.80 1.429 41.87 6.13 162.3 , Willow „ — — 13.10 29.67 I-3S2 39-61 5-80 153-6 , Fir 14.5 32.8 13-86 31-39 1.408 41.25 6.04 160.0 , Pine 137 31.0 13.88 31-44 1-392 40.82 5-98 158.2 , Scotch fir ,, 13-27 30.06 1-393 40.85 598 158.3 , Horn bean ,, 12.5 28.3 — — — — — — , Alder "3-7 31.0 — — — — — — , Larch ,, — — 1.408 41.25 6.04 160.0 II. CHARCOAL. lbs. of Lead reduced by i lb. of Charcoal according to Bertliier. Commercial Enclosed in bot- tles imme- diately after being made . Poplar charcoal Sycamore „ Ash „ Aspen „ Fir „ Aider „ Birch „ Oak Beech „ Elm Lime-tree ,, Willow „ Pine Scotch fii' ,, lbs. of Water heated from 0° to 100° C. by I lb. of Charcoal. On an average On an average 7'2 lbs. of lbs. or Water Air re- Lead heated quired r^dubed froni 0° thr by I lb. to 100° C. Perfect of Char- by I lb. Com- coal. of Char- coal. bustion Winkler. 33-56 3323 33-23 IN. 10 .3.3-51 r* bo K 3.3-71 s 33-74 eS 33-57 S 33-26 32-79 33-49 .3.3-53 33-62 o EELATIVK VALUE OF FUEL. 361 III. PEAT. Source of the Peat. Berthier Source of the Peat. Winkler. IbB. ofLead reduced by lib of Peat. lbs. of Wa- ter heated from 0° to iao° C. by I lb. of Peat. lbs. of Lead reduced by I lb. of Peat. lbs. of Wa- ter heated from 0° to 100° C. by I lb. of Peat Peat from Trnyes . „ Ham, dep. de la Si)mme . „ Bassy, dep. de la Mariie „ Framont, ddp. dee Vosges „ Ischnux, d^p. des Landes „ Konigsbrunn, Wurtemberg 8.0 12.3 ' .3.0 IS-4 iS-3 I4-3 18.I 27.9 29.2 34-9 34-6 32.4 Among 24 sorts Irom the Hartz mountains, the worst gaV'j „ „ the best 1 1.9 18.8 26.9 42.6 From Allen in Ire- land . upper „ „ lower ,, pressed peat Griffllh. 27.7 25.0 137 62.7 56.6 28.0 Karmarsch, in an extended examination of more than 100 varieties of Hanoverian peat, found a considerable difference among the individual,kinds, which could not be definitely traced to their age or other properties ; with, reference to age, however, the following mean values were obtained : 1. Young peat. a. yellow grass peat evaporated per lb. 1.78 lbs. of water, and h. brown and black peat, 2.03 lbs. of water. 2. Old peat. a. earthy peat, 1.98 lbs., and 6. pitch peat, 2.08 lbs. of water. In general, the quantity of water evaporated by i lb., ranged between 1.53 lbs. with the worst, and 2.27 lbs. with the best kinds. IV. PEAT CHARCOAL. Berthier. Berlhier. | lbs. of Wa- lbs. of Wa-, Source. lbs. of Lead ter heated Source. lbs. of Lead ter heated reduced by from 0° to reduced by from 0° to I lb. of 100° C. by I lb. of 100° C. by Charcoal. I lb. of Charcoal. Charcoal. I lb. of Charcoal. . Crou . - sur - Ourcq . Essone, much used depart. Seine et in Paris Marne 17-7 40.1 Framont, and peat 22.4 50-7 Ham . 18.4 417 from Champ du feu 26.0 589 The value of numerous other fuels as ascertained by this process will be found in the tables contained in the Appendix at the end of the volume. One pound of peat requires for complete combustion^ acccrding to the determinations and analyses quoted above, from 70 to 134 cubic feet of air at 19° 0. (66.2° r.); medium kinds require 149 cubic feet; 1 lb. of peat charcoal requires 155 to 228 cubic feet ; i lb. of brown coal, according to the experiments with lead, requires 139 to 222 cubic feet, or 160 to 248 according to analysis; i lb. of coal requires by the lead test 170 to 279 cubic feet, average qualities 228 cubic feet, according to the analysis of Richard- son from 248 to 303, according to Eegnault, those from the coal formation require 320 to 332, those from the secondary formations 293 to 326 cubic 302 RELATIVE VALUE OF FUEL. feet; i lb. of coke requires 194 to 250 cubic feet; i lb. of anthracite according to the lead experiments,- requires 233 to 277, according to Reg- nault's analysis 312 cubic feet, i cubic foot of air weighs 0.03794 lb. at the above temperature. The numbers which have been cited, and which express the relative ' quantities of heat given off by different kinds of fuel, at first appear to be in direct contradiction to daily experience. The greatest quantity of heat, for instance, is obtained from the hard woods, whilst the experiments assign the first place to lime- wood and the softer species. The accurate analyses of Schodler and Petersen explain in a satisfactory manner the observations of practical experience ; they show, that although pure woody fibre contains precisely the amount of hydrogen requisite for producing water with the oxygen, or the proportion of i of the former to 8 of the latter, yet the woods themselves contain a larger proportion, the excess of hydrogen vary- ing in the different kinds. Thus the 44. 5 parts of oxygen in oak-wood, require ^^-^ = 5.562 parts of hydrogen to form water; the wood contains, o however, 6.07 per cent., or 6.07 — 5.562 = 0.508 per cent, more than is requisite to produce water, which is equivalent to 5.08 parts in 1000. In V. BROWN COAL. Berthier. Bertbier. 1 lbs. of Lead lbs. of Wa- lbs. of Lead lbs. of Wa- Locality, reduced ter heated Locality. reduced ter heated from the from 0° to from the from 0° to Glide by 100° C. by Oxide by 100° C. by I lb. of Coal. I lb. of Coal. I lb. of Coal. lib. of Coal. Gemeinde Dauphin, St. LoD, Basses Basses Alpss 25-3 57-3 Pyrenees . 20.3 46.0 St. Martin de Van 1, Val-Pineau, dep. Canton de Vaud . 22.6 SI-2 Sarthe 19.25 43-6 Minerme, ddp. de Common German . 18.40 41.7 I'Aude 22.8 SI.6 Edon, dgp. de la Gardanne, Bjuches Charente . 17.0 38-5 du Rhone . 22.0 49.8 Alpheus, Greece . 16.3 369 Fuveau . 21.0 47.6 Triphillis „ 16.3 369 Enfant Dort 2r.o 47.6 Kumi „ 15.8 38.8 Koep Fuarch, Lake Elbojjen, Bohemia 182 41.2 ofZiiiich . 20.7 46.9 Earthy coal from RegnauU. Kiihnert. ' Brown coal from j Meissner . j Pitch coal from 20.1 58.9 Dax . „ from Bouches 21.38 62.6 j Meissner „ „ Eingkuhl „ „ Habichts wald . Glance coal from Ringkuhl . Pitch coal from 159 16.9 16.0 46.6 49. S 46.9 56. 5 du Rhone . ,1 Lower Alps „ Greece „ Cologne ,, Usnach 18.89 16.69 17.84 18.24 15.90 48.9 52-3 53 4 46.6 Habiohtswald . . 19.0 43-6 Varrei trapp. Lowest stratum, Ringkuhl . 19.0 43-6 Helmstedt, Prinz Mid.stra. Ringkuhl 1 0.0 43-9 Wilhelm's mine 20.17 59.1 Stillberger coal 14. 1 41-3 ,, other mines 2183 639 Lignite from Meiss- Scboningen, ner 14.7 43-1 Gr. Treue . 18.76 54-9 „ „ Laubauch 17s Si-3 „ other mines 18.60 54-5 RELATIVE VALUE OF FUEL. 363 VI. MINEBAL COAL. Locality and Kind of Coal. Berthier. a. Caking coal. Coal from Dowlais, in Wales Glamorgan . Eschwiller, near Aix-Ia Chapelle . Lippe-Schaumbuig Newcastle . Carmeau, near Alby Kive de Gier, Grand Croix Mens, Bouleau-Fon taine-Madame . Cannel coal, Wigan Mens, Grand-Gaillet Eochebelle, near Alais Mons, nouvelle Alliance pit . Bonchamp, Haute Saone Besseges, Aveyron St. Pierre la Cour, near Mayenne , Epinac, Saone et Loire From Oviedo, in AetHiia 31-8 31.2 31.0 30-9 30-9 30.1 29.6 29.0 28.3 28.1 27.6 27.4 27-3 27.0 27.0 26.8 26.1 hi^ fgo "S-Si S e "6*0.' s°ca fe-S>. :^h 72.0 70.7 — 70.2 69.7 70.0 80.0 70.0 7i-'i 68.2 67.0 78.0 6^.7 — 64.1 76.0 63.6 — 62.5 79-7 62.1 _ 61.8 — 61. 1 — 61. 1 60 7 72.8 59-1 Locality and Kind of Coal. Treuil mine, near' St. Etienne . Bellestat, Aude, called jet . . . . Jet (locality uulsuown) . i. Sinter coal. Cherry coal, Derbyshire Soft coal , , Oviedo, in Asturia Cannel coal, from Glas- gow . . _ . St. Georges di Laven- cas, Aveyron . Cannel coal from Lan- cashire Ombrowa, Silesia Salin, Jura . Vazas, Slavonia (!. Sand coal. Durham Eolduc, near Aix-la- Chapelle . Zinsweyer, near Offen- bi-rg g-a 25-4 24.4 23 3 27.2 26.3 26.1 24.9 24.0 23-5 21.2 21.0 19.4 31-6 31.0 22.2 S= o s oE " 57-5 55-2 52.8 61.6 59-5 59-1 56-4 54-5 53-2 48.0 47-5 43-9 71.6 70.2 50-3 ea S o) . §.5 80 VII. COKE. Species of Colie. Bertliier. lbs. of Leid reduced by lib. ofColie. lbs. of Water heated from 0° to 100° C by I lb. of Coke. A la Garre, from coal of St. Etienne From coal of Besseges „ Kive de Gier .... Gas coke from Paris 28.5 28.4 26.0 22.2 65.6 64-3 58,9 SO. 3 VIII. ANTHRACITE. Locality. Berthier. lbs. of Lead reduced by I lb. of Ahthracite. lbs. of Water heated from 0° to 100° by I lb. of Anthracite. lbs. of Water heated accordinj^ to Analysis. Anthracite from Lamure, near Grenoble From Pennsylvania From Laval jj^g^aumiere. . . . From Corbattifere, in Savoy 316 30-5 33-0 26.6 26.7 69.1 74-7 60.2 60.5 72.8 75.6 364 RELATIVE VALUE OF FUEL. like manner, we find hydrogen in excess in the following woods, in 1000 parts : Excess of Hydrogen. Excess of Hydrogen. lixcess of Hydrogen. Excess of Hydrogen. Oak-wood . 5.08 Ash . • 5-os Maple . . 8.30 Beech-wood . 6.50 Birch . . 7.50 Elm . 10.00 Poplar-wood . 8.20 Lime-wood . 13.90 Willow . 7.00 Deal . . 9.50 Pine-wood . 8.80 Scotch-fir . 7.70 Larch . . 8.60 This excess of hydrogen will give rise to the formation of gaseous hydro- carbons when the wood is heated, thus removing a considerable portion of carbofi. and proportionally diminishing the residual charcoal. It is princi- pally these gases and vapours which burn so readily, and produce the flame. The lighter kinds of wood are, therefore, characterized chemically by a larger excess of hydrogen, which causes the first stage of their combustion (combustion with flame) to be augmented at the expense of the second — the incandescence of the charcoal ; they consequently burn with greater facility or evolve their heat in a shorter space of time than the hard woods. This property may very properly be called that of greater combustibility/, and the heat given out must necessarily be greater, as hydrogen requires more oxy- gen for perfect combustion than carbon, and evolves considerably more heat. Our arrangements for applying heat, however, are generally of such a nature as to require time for the communication of the heat evolved by the fuel. If the evolution is too rapid, tlje necessary time is not allowed, and much heat escapes without serving any useful purpose. Hard woods are therefore prepared for most purposes, because the softer kinds evolve the quantity of heat they are capable of producing in such a manner as to be useless in the furnace, and not from any actual deficiency in their heating power. Whenever a very intense heat is required, as, for example, in the porcelain kilns, the preference is given to the soft woods. These remarks are equally applicable to other kinds of fuel. The time required for combustion, and consequently for the evolution of heat, is aLso dependent on the state of division of the fuel. A certain weight of wood, for example, in the form of shavings, comes much more rapidly in contact with the air than when in the form of a single compact piece. In the former case, many more portions of the wood will burn simultaneously than in the latter, and the evolution of heat will cease in a comparatively short space of time. While the compact log is slowly con- sumed, and is capable of keeping the surrounding parts (the sides of the furnace) at a moderate temperature for hours, the shavings will bring it to a red heat, although only for a few minutes. This circumstance is of great importance in practice, and accounts for the preference given to the New- castle steam coal over the Welsh. The combustibility of the fuel, however, or the quantity which is consumed within a given time, is not increased by too great a subdivision, whichleads to a directly opposite result, and ultimately, if carried to an extreme, renders the fuel absolutely incombustible. Charcoal powder, sawdust, crushed coal of the best quality, powdei-ed peat, &c., cease to be combustible bodies, if an ordinary form of grate is used, as the small particles lie so closely together that they prevent access of air. They are consequently valueless, unless the surface of the grates can be covered with blocks of sandstone, limestone, or some similar material, so as to prevent the powder from falling through the grate, and yet allow access of air, as formerly practised in some boiler-fires and glass furnaces in the neighbour- hood of Newcastle upon-Tyne, or unless burned or made into gas in special appliances. Fuel in this finely divided state has been rendered available, also, by NATURE OF FLAME. 365 various mechanical contrivances, fully described under Patent Fuel ; in this state it appears to offer some advantages over the raw material, compensating, under certain circumstances, for its higher price. Thus the carboleine of Weschnaekoff, as well as the other patent fuels, although considerably more costly than coal, may, from their superior heating power and small bulk, be employed with advantage in steam navigation. An an example, we may suppose a steamer of 1,000 horse-power, requiring for one journey 81,884 cubic feet (2,240 tons) of coal ; now, according to the observations which have been made, 0.643 parts of carboleine will do the work of I part of coal, while in addition the relative volumes of equal weights are as 0.98 to i. Sixty-three cubic feet of carboleine will therefore effect as much as 100 cubic feet of coal, or 51,587 cubic feet will be sufficient for one journey, leaving (81,884—51,587) about 30,000 cubic feet of the ship's space unoccupied. If the freight be calculated per cubic foot, and each cubic foot is charged at the rate of 5«., there will be a saving of about ^6,959, after deducting ^641 as the extra price of the carboleine. The above experimental results exhibit the comparative quantities of heat which can possibly be obtained from fuel, expressed in quantities of water raised by its means from 0° to 100° C. in temperature ; they therefore express the greatest possible amount of heat which these can produce. If the amount of heat actually obtained in practice, and made available in the arts and manufactures, be compared with this, it will be found exceedingly small. A considerable portion of the heat, therefore, which the fuel is capable of generating by its combustion, is either not evolved in practice, or is lost by the mode of application. Both cases occur ; but in order to discover the sources of this loss, it will be necessary to examine the principles on which the application of heat depends. ON FLAME. The nature and propagation of flame are intimately connected with the application of fuel, and the subject, if understood, bears directly on that of the intensity of the heat which we produce by combustion. Nature of Plame. — What is flame? Dr. Mills has remarked that a flame may be regarded as volatile matter undergoing chemical change at a visibly red heat; and Dr. Percy, with more minuteness, says: "Ordinary flame is gas or vapour of which the surface, in contact with atmospheric air, is burning with the emission of light." These definitions leave little to be desired, as they properly direct atten- tion to visibility rather than to temperature, and to the fact that the presence of combustible gas or vapour is a necessary condition to the existence of flame. We may have a solid, such as iron, magnesium, or carbon,* burning in oxygen or air, at a high temperature, with brilliant incandescence, or glowing, but without flame, whilst, on the other hand, the flame of boric methide shows that flame may exist without a high temperature. Flames are usually regarded as simple or compound according to the number of products which result from them. Those which are ordinarily used in the arts and manufactures are compound flames. From the foregoing definition of flame, it will be readily understood that all flames are more or less hollow in structure. In the centre is a space occupied by unconsumed gases ; surrounding, that is, the luminous portion of the flame; and outside of all is the non-luminous part, or " mantle," as it is called. The unconsumed inflammable gases can be collected from the centre * This is tme of single pieces of cai'bon — a mass of carbon burning in air or oxygen gene- rally shows a lambent blue flame on the surface, which is due to the burning of carbonic oxide, CO, formed by the reduction of the carbonic anhydride, CO2, in its passage through the glowing carbon. 366 TEMPERATURE OF FLAME. of the flame and afterwards ignited, and the mantle can be rendered more visible (according to Bloxam*) by burning sodium near the flame, when the mantle will acquire a strong yellow tinge. In a blow-pipe flame, the same construction is observed, the flame, however, being diminished in size and luminosity ; but by mixing air with gas before ignition, the three portions of a flame are reduced to two, with a considerable reduction in the luminosity of the flame. The combustion becomes complete at an earlier period, and the luminous cone has the same character as the mantle in the former case. Temperature and Propagation of Flame. — Some interesting observa- tions made by Devillef on the flame of carbonic oxide burned with oxy- gen show the chemical composition of the gases at various parts of the flame. He found that when a mixture of carbonic oxide and oxygen in the combining proportions (2 vols. CO to i vol. O) was allowed to issue, under a slight pressure, from a jet having an area of 5 square millim., a flame of 70 to 100 mm. high was formed, consisting of an inner and an outer cone. The outer cone, in which combustion takes place, was deep blue at the base and yellowish or nearly colourless towards the apex. In the inner cone, which was only 10 mm. high, no combustion took place, because the rapidity of displacement of the particles of gas was there superior to the very slow rate of propagation of heat in the mixture. To collect the gases from the different parts of the flame, a silver tube, pierced with a small aperture, was placed across it in the part to be examined, and the gases were aspirated by passing a rapid stream of water through the tube. They were thus quickly cooled, and, passing along the tube together with the water, were collected, by means of a bent delivery tube, in jars over water. The following table gives the results of the various observations, the first column giving the positions of the silver tube above the orifice from which the gases issued, the second column the temperatures approximately at these points, and the last division of the table the composition of the gas at the different portions of the flame : — Heif^ht above Orifice. Corresponding Temperatures. Composition of tlie Gas. CO COs 67 mm. 54 44 35 28 iS 15 12 (l) 10 hj 10 (3) Melting heat of silver, and above . Melting heat of gold .... Commencing white heat of platinum White heat of platinum Strong white heat of platinum . Intense white heat of platinum Incipient fusion of platinum Melting point of platinnm Sparkling of the melted plalinum Still higher temperature 0.2 6.2 10,0 173 19.4 29.0 40.0 47.0 SS-3 55-1 64.4 21.3 28.1 20.0 24.8 26.S 25.1 329 36.0 35-3 36.5 33-3 78.5 657 70.0 57-9 54. 1 459 27.1 17.0 94 8.4 2-3 (1) A little above the apex of the inner cone. (2) Somewhat below the apex of the inner cone. (3) Original mixture. These numbers show that the highest temperature is at the apex of the inner cone or a little below it ; that the temperature gradually diminishes towards the apex of the flame ; and that the quantity of carbonic anhydride increases in the same proportion from the apex of the inner cone, where, at most, |rds of the carbonic oxide and oxygen enter into combination, to the ♦ " Chemistry," edition 1867, p. 95. f "Bull, 80C. Ohim." [2], v. in ; also Watts, "Diet, of Chemistry." TEMPEEATUEE OF FLAME, 367 vertex of the flame itself, where carbonic oxide can no longer be detected. At the apex and edges of the inner cone, the carbonic oxide and oxygen unite almost instantaneously, but only partially, on account of the very high temperature there existing.* Bunsen also carefully investigated this subject, and introduced t some modifications of the views held previously. Watts (Diet, of Chem., i. 860, Aflnnity) has summarized this matter as follows : — When a combustible gas mixed with oxygen is set on fire, a rise of tempera- ture takes place, which, supposing the combustion to be perfect, may be calculated from the heat of combustion of the gases and the specific heat of the products. If, on the other hand, the combustion is imperfect, the tem- perature may still be calculated with the aid of Mariotte's and Gay Lussac's laws, provided the pressure exerted by the gaseous mixture when exploded in a closed vessel be known. This pressure has been determined by Bunsen for mixtures of hydrogen and carbonic oxide with oxygen, or with oxygen and nitrogen together, by means of a eudiometer having a loaded safety valve. From this and the observed temperature of combustion, the quantity of the combustible gas (carbonic oxide or hydrogen) which has been burnt at the moment when the flame attains its maximum temperature, and thence also the quantity which at this temperature has lost its power of combining, may be calculated. • The following table contains the results of Bunsen's experiments arranged according to the maxima of temperature (t' — t) which the seyeral gaseous mixtures, calculated for volumes at 0° C, attain by combustion in a closed p vessel. , Columns I. and II. give the mixtures of gases used ; --^ = the o pressure produced in atmospheres by explosion ; t = the calculated tempera- tures ; and k = the calculated proportion of combination. Mixtures of Gases. p t k No. PQ MeaD. Deviation from Mean I I. with II. III. IV. v. 1 rol. CO + J fol. 10.78 3172° 0-35I ] -1- 0.0194 2 § „ CO + ; >, II. 19 2893 0.319 -0.0126 3 § „ H + i „ 9-97 2854 0.338 0.3316 0.336 0.314) + 0.0064 4 1 „ H + ; ,. 9-75 2833 + 0.0044 5 1 „ CO + , ,, + 0.1079 toI. 9- OS 2558 -0.0176 6 s „ CO + ; „ + 0.6857 „ CO 8.89 2471 0.460' -0.0421 7 i -, CO + i „ + 0.8854 „ 8.44 2325 0.478 -0.0241 8 „ CO + ,; „ + 1.0861 „ 7.86 2117 0.490 -0.0121 9 „ CO + , „ + 1.2563 „ N 7-73 2084 0.515 + 0.0129 10 „ H -1- ;; „ + 1.2599 „ N 7-49 2024 0-54.7 0.5021 + 0.0449 II „ CO + J „ + 1.2563 „ N 7-35 1909 0.470 -0.0321 12 „ CO + ; „ + 1.7145 „ 6.67 1726 520 + 0.0179 13 „ CO + „ „ + 2.1559 ™l3 5-83 1460 0.512 + 0.0099 14 „ 00 + i „ + 3.1629 „ CO 4-79 1 146 0.527; + 0.0249 These numbers, in Bunsen's view, show that, in a mixture of carbonic oxide or hydrogen with the exact proportion of oxygen required for com- bustion, and unmixed with any diluent gas, only ^rd of the carbonic oxide or hydrogen is burnt at the maximum temperature, whilst the other frds, by being raised to the high temperatures of 2558° to 3033°, have lost the power of combining ; moreover, that, when i volume of the same mixture is diluted with 0.686 to 3.163 volumes of any gas that does not burn with it, and the temperature of the flame is successively reduced thereby from 2471° * See also Thorpe on the Theory of the Bunsen Lamp, "Jour. Chem. Soc," 1877, i. p. 627, for Blochmann's inTestiarations, or " Annalen Chem. Pharm.," vol. clxviii. p. 295. t "Phil. Mag.," vol. xxxiv. p. 489, and '-Gasometry," by E. Bunaen. 368 TEMPEEATUEE OF FLAME. to 1146°, then, at all temperatures within these, exactly half of the carbonic oxide or hydrogen is burnt, the other half having lost the power of com- bining. From this it has been inferred that the combustion of gases takes place in a manner different from that which had been previously supposed. When a mixture of 2 volumes of carbonic oxide with i volume of oxygen is set on Dre, and its temperature thereby raised from 0° to 3033° C, two-thirds of the carbonic oxide remains in an unburnt, and for the time incombustible, state. The temperature is then lowered by radiation and conduction froip 3033° to 2558° without any combustion of the carbonic oxide, but when the tempera- ture falls somewhat lower, combustion recommences, restoring the heat lost by radiation and conduction, and raising the temperature again to 2558°, but not above that point. The gradual fall of temperature from 3033° is followed by a continuance of the temperature 2558° till exactly half the carbonic oxide is burnt, whereupon a third phase sets in, during which, again, no combustion takes place until the inflamed gaseous mixture has cooled down to at least 1146°. As, however, the gaseous mixture, after cooling, consists almost wholly of carbonic anhydride, these alternate phases of constant and decreasing temperature must be repeated below 1146° until the last portion of the gas is burnt. This discontinuous combustion of a uniform mixture of a combustible gas with oxygen is referred by Bunsen to a law of combination established by him. These facts, as observed by Bunsen, are of great importance in connectiok with the inflammation of gases, although it is probable, as Berthelot has indicated, that Bunsen's temperatures are too high in consequence of his not having considered the contraction of volume due to combination. Berthelot* announced that the combustion temperatures in Bunsen's experiments may be anything between the limits shown in the following numbers, keeping the same numerical order as in the foregoing table : — No. ti t2 No. t' t' I 4140° 2612° 8 2280° ■!^r 2 3900 2537 9 2203 1838 3 3809 2449 10 2126 1715 4 3718 2389 II 2083 173+ 5 3066 2198 12 1875 1548 6 2760 2154 13 1505 1319 7 2537 2031 14 1150 1034 A number of experiments on this subject have been made since Berthelot's criticism appeared, but the conclusions arrived at are contra- dictory. All, however, agree in observing a great absorption of heat at high temperatures, which is thought to be due either to a change in the specific heat of gases or to dissociation. Messrs. Berthelot and Vieillet and Mallard and Le Chatelier J have advanced and supported the former view, while the latter has been advocated by Mr. Dugald Clerk § and Prof. EUcker of Leeds. It is probable that both causes operate to produce the phenomena which have been observed. The rate of ignition of gaseous mixtures is also a point of considerable importance. Sir H. Davy|| propounded a theory of this action, but it does not seem to be entirely supported by more recent investigations. * Ann. de Chim. et Phys., [5] vol. xii. pp. 302-310; "Jour. Chem. Soc," vol. xxxiv. p. Si Compt. Rend., vol. Ixxxiv. (1877), p. 407. t Essai de Micanique Chimique, Paris, 1879 ; Ann. de Chim. et de Phys., sme ser. xxvii. and ,xxviii. ! 6mc ser. iv. pp. 13-84. t Compt. Bend., 1880, 1881, vols, xci., xciii. ; Annates des Mines, 8mc aer. Memoires, iv. p. 274- § On the Theory of the Gas Engriue. " Min. Proc. lust. -CE ," vol. Ixix. part iii. ; also iiirf. vol. Ixxxv pp. 1-53. See also Eossetti, On the Temperatures of Flames, "Jour. Ohem. Soc, vol. xxxiv. pp. 467, 694. &c. II " Kesearches on Elame." See also Watts, Diet, of Ohem., " Combustion." i. io8g. PROPAGATION OF FLAME. -go Bunsen found that the velocity of the propagation of combustion in a pure detonating mixture of hydrogen and oxygen was 34 metres per second, and in a maximum explosive mixture of carbonic oxide and oxygen it was less than i m^tre per second. When the explosive gases are gradually diluted with a gas that does not take part in the combustion, the rate is lowered, and it can be brought down thus until the progress of combustion is made visible to the eye. Bunsen's method of determining these velocities is thus described by Dugald Clerk {he. cit.) : — The explosive mixture was allowed to burn from a fine orifice of known diameter, and the rate of the current of the gaseous mixture was carefully regulated by diminishing the pressure to the point at which flame passed back through the orifice and ignited the gases below it. This passing back of the flame occurs when the velocity with which the gaseous mixture issues from the orifice is inappreciably less than the velocity with which the inflammation of the upper layers of burning gas is propa- gated to the lower and unignited layers. Professor Mallard,* of the Ecole des Mines, made a series of observations by this method on the rate of the propagation of combustion in mixtures of coal gas and air, and of marsh gas and air. In the latter mixtures, the maximum rapidity of inflammation was found to be about 0.56 metre, or rather more than half a yard, persecond. This velocity was attained with a mixture of i vol. marsh gas and 8 J vols. air. "When the proportion of air was increased to 12 vols, or diminished to 5.9 vols., the mixture was neither explosive nor inflammable.f Prof. Thorpe remarks on this that it is worthy of note that the proportion of air corresponding witli the maximum rate of inflammation is less than that which contains oxygen sufficient for the com^- plete combustion of the marsh gas. This, however, is what the observations by Bunsen and others, previously quoted, would lead us Co expect. The maximum rapidity of inflammation in mixtures of coal gas and air was attained with a mixture of 5 volumes of air and i volume of coal gas, and was 1.02 mfetre, or rather more than i yard, per second. One volume of coal gas with 6^ vols, of air gave a rate of 0.285 m^tre, or 11 inches, per second. The rate was very rapidly diminished by an excess of either constituent ; a mixture containing more than 8 vols, and less than 3 J vols, of air to i of coal gas was found to be uninflammable in the way described.+ Dugald Clerk has pointed out that these are the rates of ignition at constant pressure, and that in a closed space the conditions of inflammation are quite difierent in consequence of the expansion of the ignited portion and mechanical disturbance of the remaining part of the gaseous mixture. Experiments are needed to determine the rate of ignition for constant volume. Some remarkable results are given by this author, which were obtained by so arranging the plan of ignition that a small volume of gases was first ignited, which expanded and projected a flame through a passage into the mass of an inflammable mixture, thus adding to the rate of ignition the mechanical disturbance produced by the entering flame. He succeeded by this means in producing maximum pressure (or maximum ignition) in y^th part of a second in a space containing 200 cubic inches of' gas. By firing a mixture with varying amounts of mechanical disturbance, almost any time of ignition could be obtained between j-J^th and j^th of a second. It did not matter whether the mixture used was rich or weak in gas ; the rich mixture could ' Anrmles des Mines, vol. vii. 1875. p. 355. Thorpe, On the Theory of the Bunsea Lamp, "Jour. Chem. Soc," 1877, i. p. 631.- t See also Coquillion's results in " Jour. Chem. Soc," 187", i. p. 166, and in Compt. Rend., 1876, vol. xxxiii. p. 709. i Compt. Hend., vol. xov. pp. 151-157 ; Ann. de CUm. et Phys., [6] vol. vi. 1885, fip. 546, 556. B B 370 LUMINOSITY OF FLAMES. be fired slowly, and the weak one rapidly, just as was required. He found that the rate of ignition of the stronge.st possible mixture is so slow that the time of attaining complete inflammation depends on the amount of mechanical disturbance permitted. Mr. Lewis T. Wright has recorded* some interesting observations on the velocity of the propagation of flame, and has announced that, when flame travels at a greater velocity than 4|feet per second, it will pass through the gauze used in safety lamps. He also found that a flame of low velocity in a confined space may become so much agitated by an increase in its own oscillations as to cause the introduction of a very rapid rate of ignition in the remaining portions of the gaseous mixture. He remarks that " a defi- nite explosive mixture may have a velocity of propagation of flame, when it is undergoing explosion of the first order, as low as i ^ foot per second ; but when it becomes sufficiently agitated to give an explosion of the second order, the rate of propagatiob of flame is several thousand feet per second." The following table shows the results of experiments with various mixtures of gases, giving the rate at which an explosion of the first order (that is, a slow ignition) travels with each mixture in a glass tube 13 feet long and 0.75 inch diameter : — Mixtures. Lineal Velocity of Kfflux of , ftjixture. Rate at whicll Explosion of First Order travels in Tube. Total Velocity of Propagation of Flame. Gas. Air. Feet per Second. Feet per Second. Feet per Second. 'o-37o 12.2 15.0 17.7 19.6 21.2 22.1 23.0 897 7o 87.8 85.0 82.3 80.4 78.8 7'7-9 77.0 1. 21 1.32 1-39 1.41 I.I 2.0 4.8 30 2.4 1-3 Stationary 2-31 4.28 6.12 4-35 378 2.69 Wright also found that, whenever an explosion is produced inside a safety lamp having ordinary gauze, the flame was projected through the gauze, and could ignite gas at a considerable distance from the lamp. By employing stiff wires for the woof and lightei- wires for the warp, he pro- duced a " basket-work " gauze having small tortuous openings and a rela- tively large weight of metal, which did not allow flame from an explosion to pass through. Iiuminosity of Flames. — According to the commonly received theory of the causes of luminosity in flames (first propounded by Sir H. Davyt), the presence of solid particles suspended in the flame (or in immediate contact with the burning gas) is essential to its luminosity. There is no doubt that the introduction of solid particles in a fine state of division into a flame of feeble luminosity will impart to it a considerable degree of brilliancy by the incandescence of the .solid particles, or perhaps in some cases by reflection of the light from their many surfaces. No sound conclusion, however, as to the luminosity of flames in general can be drawn from such an analogy as is afforded by the result of such an experi- ment, because T3Tidall has shown that the same result is produced when the solid introduced is one that does not burn. The presence of solid particles, according to the common idea, in luminous flames is only assumed, not * " Jour. Soo. Chem. Ind.," vol. vi. pp. 362- 364. f " i'aii. Irans." for 1817, p. 75. t LUMINOSITY OF FLAMES. 37 1 proved. It is usual, however, to refer to the black deposit which is formed upon a glass rod or similar body, when it is held in the flame of a candle or of hydrocarbon gas, as a proof that such flames contain solid particles. This, however, is not a conclusive proof, for Dr. Frankland* has pointed out that this deposit is not pure carbon, but is a hydrocarbon compound. To this Dr. Percy t objects that it is fixed, not volatile, whatever its com- position may be ; but the objection seems to be irrelevant, because it refers to the substance as deposited, and we do not know that such a substance existed in the flame. The introduction of the cold surface of the glass rod not only condenses some vaporous hydrocarbon, but doubtless also causes decomposition of some of the many hydrocarbons which make their appear- ance in the gradual resolution of carbonaceous matter. As, therefore, we do not know in what combination this substance producing the black deposit existed while it was originally in the burning gas, it cannot properly be asserted that it was " fixed, not volatile " The phenomena of many luminous flames are explained by various writers, with more or less ingenuity, on the hypothesis of solid particles, but the experi- ments and observations of Dr. Frankland J have shown that that hypothesis is not wholly satisfactory, because luminous efiects have been produced where it could not account for them, such, for example, as the luminosity of the flame of hydrogen burning in oxygen under pressure, and, secondly, because in many of the brightest flames the temperature is such that fuliginous matter § could not exist in them. In many cases, it might seem, therefore, to be a more satisfactory explanation, that the luminosity of flames depends on the existence of a comparatively high temperature, and on the presence of gases or vapours of considerable density. || % The efiect of high temperature is seen in the greater brightness of the flames of sulphur, phosphorus, and, indeed, all substances when burnt in pure oxygen, as compared with the result of their combustion in air. Direct evidence of the eifect of high temperature is also afforded by the combustion of phosphorus in chlorine, for, whilst at ordinary temperatures only a feeble light is produced by this combustion (although the product PCI3 has con- siderable density), strongly heated phosphorus vapour burns in hot chlorine with a dazzling white light. A comparison of the relative densities of gases and vapours shows that the brightest flames in general are those which contain the densest vapours. • "Proc. Eoy. Soc Lond.," vol. xvi. 1868; "Phil. Mag.," vol. xxxvi. 1868, PP- 309-311 ; "Experimental Researches;" '' Lectures on Coal Gas." t " Metallurgy," vol. " Fuel," p. 158. t Op. at, and " Jour. Chom. Soc. Lond.," 1864, vol. xvii. pp. 52-55 ; "Brit. Assoc. Reports," vol. xxxviii. p. 37 ; " Proc. Roy. Instit.," vol. v. 1869, pp 419-423 ; "Proc. Roy. Soc. Lond.," vol. xxx. No. 201. § See lectures on Coal Gas, delivered at the Royal Institution, London, March 1867, by Br. Frankland, published in "Jour, of Gas Lighting," &c., Loudon. II "Jour. Soc. Ghem.," 1862, vol. xv. p. 168; Watts, "Diet, of Chemistry," ist sup., p. 485. % [Although it may be that in excepti0n.1l cases the luminosity of a flame is due to incan- descent vapour, it would be incon-ect to suppose that this ia invariably true of the luminous flames produced by the combustion of hydrocarbons and other carbon compounds, Soret's experiments (^Phil. Mag. 1875, p. 50), recently extended and confirmed by Burch (Nature, vol. xxxi. p. 272), would seem to prove incnutestably that the luminosity of a candle flame at all events is due to intensely ignited solid matter. It was found that when the image of the sun was thrown by means of a lens on to the flame of a candle, a spot of light appeared, aud this light, on examination by a spectroscope, showed all the Fraunhofer lines distinctly. Moreover, when examined by means of a Nicol's prism, the light was found to be completely polarized at right angles to the line of incidence, proving that it was reflected from solid particles. We can scarcely doubt that the luminous flames of hydrocai bous, &c., when examined will give precisely similar results. — Editok.] B B 2 lES OF SOME GASES AND VAPOURS. I Oxygen 16 • 9 Carbon dioxide . 22 . i84 Sulphur dioxide . 32 • 9l Phosphoric oxide 71 or 142 . 150 Chlorine 355 . 198 Mercury . . . . 200 • I4-S 372 LUMINOSITY OF FLAMES, RELATIVE DENSITIES Hydrogea Water Hydrochloric acid Arsenious chluride Metallic arsenic Arsenious oxide Air Hydrogen burning in chlorine produces a vapour more than twice as heavy as that resulting from its combustion in oxygen, and accordingly the light produced in the former case is stronger than in the latter. Carbon and sulphur burning in oxygen produce vapours of still greater density (viz., OO3 and SO^), and their combustion gives a still brighter light. Phos- ,phorus, also, which has a very dense vapour, and pelds, in burning, a product of great vapour density, bums in oxygen with a brilliancy almost blinding. The luminosity of a flame is increased by compressing around it the surrounding gaseous atmosphere, and is diminished by rarefying it. Thus, mixtures of hydrogen and carbonic oxide with oxygen emit but little light when they are burnt or exploded in free air, but exhibit intense luminosity when exploded in closed vessels so as to prevent expansion of the gases at the moment of combustion. Frankland experimented with jets of hydrogen and carbonic oxide burning in oxygen under a pressure which he gradually increased to twenty atmo- spheres, and obtained brilliant luminous effects, including bright and con- tinuous spectra. Even the faint flame of alcohol, as in an ordinary spirit lamp, becomes highly luminous under the receiver of a condensing pump, when the pressure of air is increased to 120 inches of mercury. We are indebted to Frankland * also for the observation that the diminu- tion in illuminating power is directly proportional to the diminution in pressure ; and, as applied to ordinary domestic gas-burners, this means that, as the barometer falls, the light from them diminishes at the rate of 5.1 per cent, for every inch of fall. According to Dr. Letheby,^ "in London the difference in the value of the light when the barometer is 31, as compared with what it is at 28, is fully 25 per cent." The flame of arsenic burning in oxygen may also be rendered quite feeble by rarefying the oxygen ; and, at high altitudes, flames exhibit the effects of rarefied air. Tyndall and Frankland J made observations on the combustion of stearin candles at the summit of Mont Blanc and at Chamouni, and found a considerable decrease in luminosity at the high elevation, although the rate of combustion of the candles remained the same in both places. The energy of combustion was therefore unaltered, although the flame in one case had a higher temperature than in the other, resulting from the increased density of the gaseous atmosphere. Percy shows (vol. " Fuel," p. 159) that this con- clusion should be drawn even from the theory propounded by Tyndall in explanation of the diminished luminosity which he observed on Mont Blanc. Tyndall's theory was, that the decrease in luminosity was mainly due to the greater mobility of the air. From this Percy reasons, " Now, if increased mobility of the air be caused by rarefaction, the opposite should result from compression, in which case the movement of the particles would become sluggish, intermixture of the air and flame-producing gas would be less rapid, and the diffusion of the gaseous products of combustion in the surrounding air would be retarded, with consequent increase of temperature." • Op. cit., and "Phil. Trans.," vol. cli. 1861, p. 629. t " Common Sense for Gas Users," by R. Wilson, p. 19 (London : Crosby Lockwood & Co.). t "Heat Considered as a Mode of Motion," by J. Tyndall, F.E.S., 1865, p. 50. PREVENTION OF SMOKE. 373 Frankland's conclusions have also been confirmed by some experiments made by Prof. V. Wartha* on the influence of pressure on flames. ON THE APPLICATION OP FUEL. Prevention of Smoke. — In the practical application of fuel, the most pressing question in these days is how best to use it for domestic and industrial purposes while securing abatement of the smoke nuisance. There is a considerable amount of difference between the conditions as to the supply of fuel under which this problem must be worked out for domestic purposes and those 'involved in its relation to industrial operations, for this reason, these really constitute two branches of the subject, which must be considered to some extent apart. The prevention of smoke, or even the abatement of the smoke nuisance in towns, depends on the degree of completeness of combustion which is secured, and it is not impossible to secure the fullest degree even with the use of fuels which have a greater tendency to burn with smoke than others have. For instance, although, with ordinary appliances, methane or marsh gas burns without smoke, yet it has been made to produce smoke in burning by limiting the air supply (see Lewis T. Wright, Jour. Chemi. Soc. Trans. 1 885, pp. 201-2); and, on the other hand, a naturally smoky fuel, Uke benzene vapour, can be made to burn without smoke by mixing it with air previous to ignition.t Wax, stearin, and olein are less liable to burn with smoke than paraffin, because of the amount of oxygen which they contain, and that in spite of their larger proportion of carbon. A good practical illustration of the conditions affecting the presence or absence of smoke in combustion is afforded by the argand gas-lamp for ordinary illuminating gas. When this gas is burned in the lamp without a glass chimney, a long smoky flame is produced ; but as soon as a chimney is applied the flame is shortened, ren- dered brighter, and free from tendency to smoke under almost any conditions of the surrounding atmosphere. The effect of the chimney is, as is well known, to induce a better distribution and a more intimate contact with the flame of the air supply, which is also partially heated, and thus rendered effectual in producing a higher temperature of combustion. ' The great requisites for perfect combustion are — (i) intimate mixture and contact between the particles of the combustible and the air, and not mere access of even an unlimited supply of air, and (2) the maintenance of the most suitable temperature for the chemical combinations involved during the whole period of the combustion. Where these are secured, whether in domestic or in industrial appliances, the best results are obtained from the fuel, and the production of smoke is prevented. In using solid fuel, how- ever, it is practically impossible to ensure the accomplishment of all these conditions, as only the surface of the solid can be in contact with the air. Moreover, in order to secure the maintenance of a sufficiently high tempera- ture to ensure combustion, one part of the fuel must be burned to carbonic acid, and this gas, passing through other portions of the fuel, unites with more carbon, and is reduced to carbonic oxide, which, if hot enough, when brought into contact with air, ignites, and burns to carbonic acid again. It will be understood that different and varying quantities of air are re- quired for these different operations, and, as in the majority of instances it is impossible to regulate this supply in any adequate manner, the use of solid fuel is consequently subject to loss from various causes ; these include the dilution and cooling of the carbonic oxide produced, so that some of it passes off unconsumed when an excess of air is admitted, or a similar result in loss * Jour, fiir' Gaabeleuchtung, vol. xix. p. 761 ; " Min. Proc. Inst. C.E.," vol. xlviii. part ii P- 329' t See Bloxam's " Chemistry," pp. 97, 98, edition 1867. 374 COKE FIRES. of carbonic oxide when the air supply is insufficient, the formation of smoke, &c. The thermal results produced by the use of solid fuel are also ■unsatisfactory in view of that which is theoretically attainable supposing- perfect combustion and the absence of any excess of air; further, the requirements of the operation of charging fresh quantities of fuel periodi- cally, and the removal of ash and cinders in a heated state, also constitute sources of loss of heat. Calculations of these losses are given in several works, including Rankine's Steam Engine, &c., Box's Treatise on Heat, Galloway's Fuel, vhich have been most generally adopted, or which recommend themselves to our notice, for securing a uniform temperature in private dwellings or public buildings at all seasons, whilst they promote the equally important object of an efficient ventilation ; and, secondly, to a few illustrations of the mode of application of fuel in the more important processes of the arts or manufacture in which it is essential. In order to render a room or dwelling comfortable, the air contained in the entire space must be kept as far as possible at a uniform temperature, ranging from 56° (i3°.3 0.) to 70° F. (21°.! C), considerably higher, there- fore, than that of the atmosphere during winter in most civilized countries. When air is warmed, it expands and becomes lighter, and, being a bad con- ductor of heat, a constant movement of the air is produced in any confined space into which a hot body is introduced. The warmer portions ascend and give place to the colder as long as the inequality of temperature con- tinues, so that the internal temperature of a room can never be retained above that of the colder exterior without a constant circulation of the enclosed air. The velocity acquired by this current depends on the extent of the heating surface employed, and on the difference of temperature between it and the air of the room ; it is not, however, in direct proportion, but in the ratio of the squa,re root. If the air in the room, for example, is 60° F., and the surface of the stove at one time 176° F., and at another 212° F., the current in the latter case will be . / -1 — = more rapid. Again, as heat from V 212-60 1.14 ^ ^ any source is communicated by radiation, as well as by conduction, the more distant layers of air become warmed by contact with bodies heated in this manner, and ascend in consequence. Rooms might be easily and quickly heated at a small cost of fuel, if several unavoidable circumstances did not combine to withdraw the heated air and diminish its temperature. In the first place, the walls of the room, the windows, and doors constantly absorb heat, and evolve it again externally. The amount of heat lost in this way varies with the nature of the material, and also directly as the difference of temperature of the two surfaces and inversely as the thickness. According to Box (Practical Treatise on Heat), this may be expressed by C = X d -- E, where C = the loss by conduction in units per square foot per hour, = the conducting power of the material, E = the thickness in inches, and d = the difference of temperature of the two surfaces. Secondly, the air in the interior being warmer and lighter, and consequently not in equilibrium with the external air, all crevices in windows and doors will allow cold air to stream in from below, while hot air passes out above. Lastly, in order to render the atmosphere healthy and fit for respiration, it is absolutely neces- sary that the air which has once passed through the lungs and the skin should be replaced by fresh air, which must generally be supjjied cold from the outside. According to Munke's estimate, the loss of heat from these 378 . CHIMNEYS. causes, after deducting what ^ necessarily incurred for ventilation, amounts in twelve hours to 5 times, and according to another estimate, to 6 times the quantity of heat that is required to raise the temperature of the air confined in a room of ordinary dimensions to 68° F. Every special case however, will require a separate estimate. This loss is partly compensated by the vital heat of the persons present in the room, as also by the lamps, gas, or candles which are burnt ; but it is certain that the greater part of the fuel required for retaining the air of a room at the proper temperature is consumed in making up for this constant loss of heat. Double windows and .doors, and similar contrivances, which enclose a stagnating layer of air, materially lessen the loss of heat. During the time that a door is open, the warm air streams out from above, whilst the cold enters from below, as may be observed by holding a lighted taper in the two regions, the current being more rapid the greater the difference of temperature between the external and internal air. It is very advantageous, therefore, to allow the doors to open into warmed ante-rooms, so that warm instead of cold air may be admitted. The loss of heat occasioned from these circumstances may be approximatively ascertained by observing how much the temperature of a room sinks in a given time after the extinction of the fire. When the air of a room is to be heated, the surface from which the heat is evolved is constructed so as to combine the necessary arrangements for the combustion of the fuel and the conduction of the heat. All the con- trivances for communicating heat to apartments, however they may vary in outward form and dimensions, comprise a space for the combustion of the fuel ; an area from which the heat is diffused ; and lastly, some means of creating a draught, generally a chimney or flue, to draw the necessary air and carry away the products of combustion. The two primary conditions which are essential to every arrangement are — the maintenance of a tempera- ture capable of consuming the material, and the supply of the amount of air (oxygen) necessary for combustion. If either of these be neglected, as they invariably are to a certain extent in practice, imperfect combustion v/ill be the result, and consequently a defective evolution of heat. Chimneys. — The air that is required for combustion is sometimes supplied, as in metallurgical processes, by machines for the purpose, but in most cases, as inordinary stoves, kitchen-ranges, copper-fires, 49 . To ascertain the practical relation of loss to useful effect we 78. I have to allow for the useful effect of steam engines and fans. Engines give out only 0.055 per cent, of the power of which the heat of steam is capable, and the useful effect of fans is not more than o.io to 0.20 per cent. The practical relation at which we wish to arrive may therefore be ex- pressed by 4> 49 ^ °-°°55 _ _£_: — which amounts to saying that to pro- duce the movement of air in fires by the natural draught of chimneys we spend 26 times as much heat as we should need to spend in order to produce the same effect by means of a steam-engine driving a fan. This result will be altered in favour of the mechanical method by the adoption of a higher temperature for the escaping gases. The quantities of heat carried off by these gases when discharged at 600° F. and 1000° F. respectively have been estimated by Mr. John Morrison,* who has also shown the advantage of transferring a portion of this waste heat to the supply of air used for combustion. Supposing i lb. of average Newcastle coal to be capable of yielding 10,000 heat units, and to require for its combustion an average of 24 lbs. of air, the waste gases would amount to 25 lbs,, with the following result as to heat absorption : — • • On Combustion, " Jour. Soc. Cliem. Ind.," vol. 1883, p. 79, f-J, Z"1 > FOECED COMBUSTION. 387 lbs. Speo. Heat. COj . . 37 X .217 = .8029 . . . 2.8 X .218 = .6104 N . . . 18.5 X .244 = 4.5140 25.0 5-9273 heat units necessary to raise the gases i degree F. " Consequently, if these gases were discharged into the chimney at 600° F. over the initial atmospheric temperature, 5.9273 x 600 = 3,556 heat units out of a possible 10,000 would be entirely absorbed in draught production; while, if they were discharged at 1000° F. over the atmosphere, the loss with the same consumption of air would reach 5,927 heat units, an amount con- siderably exceeding one-half the entire calorific value of the fuel." Regarding the transference of heat to the air-supply, which, with methods of forced combustion, is possible to an extent impracticable where chimney draught is employed to supply the necessary air, Mr. Morrison remarks : — " Supposing the provision of suitable arrangements for heating the air-supply free of expense (by means of the more or less highly heated waste gases) to a temperature of, say, 300° F. over the atmosphere, then 300 x .2374 (specific heatof air)= 71 units x 25 (air used for combustion) = 1,350* units, or i3jper cent., would be added to the 10,000 produced with normal air ; while, if the temperature were similarly increased by 600° and 1000° F., the augmentation of efficiency would respectively be 27 and 45 per cent. Or, in other words, with an air-supply exceeding the normal atmospheric temperature by 300°, 600°, and 1000° F., 17^, 14!^, and 11 cwts. would respectively perform the duty of I ton of fuel burnt with a similar weight of ordinary cold air." Methods of applying, in greater or less degree, the system of forced com- bustion to steam-boilers have been devised or described in this country after Prideaux by F. J. Rowanf (1876) ; Capt. Hamilton Geary, E.A. J (i877),as applied to burning anthracite in marine boilers ; E.. W. Perkins and J. F. Flannery§ (1880), also primarily for burning anthracite; R.J. Butler;|| James Howden;^ and R. Sennett, R.N.** Other plans ft may have been pro- posed, but those mentioned are sufficient to illustrate the subject. In aU but the first two, the object aimed at has been merely to supply the air required for combustion at a rate sufficient to produce a higher temperature of com- hustion than is usually obtained with ordinary draught. Ventilation of the stokehold and the convenience of a closed stokehold caused the introduction of the system into vessels of the Royal Navy where economy of fuel was not an object in view. In the first of the later plans mentioned, the purpose was to increase the pressure under which combustion was carried on in addition to supplying the air mechanically, the arrangement adopted for slightly increasing the pressure also providing means for retarding the escape of the gaseous products of com- hustion. Mechanical or artificial draught thus presents to us a method of econo- mically furnishing the air-supply to furnaces and producing a more efficient combustion temperature, while it also renders possible further economies due to retarding the movement and escape of the hot gases, to preliminary heating of the air-supply by waste heat or otherwise, and to carrying on combustion under a pressure higher than that of the atmosphere. * This number should evidently have been 1,775 '■ •"■> ^ 24 lbs. of air were assumed as above, then 1,700 units. — Ed. t British patent, No. 4,430—1876, " Mio. Proc. Inst. C.E.," vol. liv. pp. 131, 172 ; " Engineer- ing," vol. xxvi. pp. 164, 283; "Brit. Assoc. Eeports," 1878. t "Jour. Roy. U.S. Inst.," vol. xxi. p. 956. 5 " Trans. I.N.A.," vol. 1880. II Ibid., vol. 1883. ^ Ibid., vols. 1884 and 1886. " Ibid., vol. 1886. tt See also " On Forced Draught," by J. Patterson and M. Sandison, " Trans. N.E. Coast Inst. Eng. and Shipbuilders," March 3, 1886. C C 2 388 COMBUSTION UNDER PRESSURE. The possibilities of combustion under increased pressure have scarcely been considered in a practical way as yet. Frankland's researches * and experiments serve to point out the way to what is a promising field of investigation, merely waiting for quantitative results to complete the qualitative work already done ; but attempts at practical application have been few. Bessemer introduced a very interesting system of high-pressure furnaces in the year i869,tbut evidently put it into practice only on a very limited scale. The following explanation of the principles involved in it, or in any similar plan, was, however, published by Mr. W. H. Maw :q: — "When combus- tion is carried on under pressure, the resulting products of combustion occupy a less space than they would if produced under the ordinary pressure of the atmosphere, and thvis a portion of the heat which would have been rendered latent in causing their expansion is left available for raising their tempera- ture. The experiments of Poisson and Laplace showed that the specific heat of air when maintained at a constant volume is but 0.169, whereas when maintained at a constant pressure it is 0.238 (that of water being unity), or, in other words, that a pound of air, in expanding to the extent corresponding to a rise of temperature of i degree, absorbs or renders latent 0.238 — 0.169 = 0.069 of a unit of heat. It is this fact which explains the heating of air which takes place when it is compressed, the heat which had been employed in maintaining it in an expanded state being by the act of compression rendered sensible, and the temperature of the air raised accordingly. The compression of the air does not increase the quantity of heat contained in it, but. merely renders sensible a portion previously latent. " Now, in carrying on combustion under pressure, the products are not allowed to expand and then be heated by re-compression, but they are prevented from expanding as they would under ordinary circumstances, and, so far as efiects go, the results are the same. In other words, the tem- perature to be expected in a high-pressure furnace working at a pressure of, say, two atmospheres, will be the same as if the products obtained by com- bustion under ordinary atmospheric pressure were, before becoming at all cooled, suddenly compressed to one-half their volume. The increase of tem- perature due to compression in this way may be calculated by the well-known formula for air : — T= |(. § g c» P en I IS ~ s TJ5STS OF GAS-BUENJiRS. 415 "ft !? ^ ^ cd n « "^ In, M N 10 ■♦ ? 3; & m S" s, £ s 8 .8 • (^ C4 N « Ch ff w -s -& S « 8. t>. in ro in ro N ■* M c^ 0. ^ r^ r^ ^0 m It 00 00 8. 8 (^ 2- ? 8- R ■«• m ■^ eft ^ « ro " in M t* t^ C4 \n « m ? ? to 00 ^ a. g- Ox S, ■i- ?, 8, •s %■ S, £. s m 00 N s « t* in 1 t 1 1 1 1 1 1 n en 1 I 1 1 1 1 1 1 i/i ^ 5 -a S • .3 -£. S -§ ^ h9 -^ -S 111 ^ • s « ^- in C t^ . « o S S o- o- dij « O ^ ~ o b£ U ." -^ ■« ,= 1 > =y J " s M V3 g bo 9 CO wit Ditto refl S ! '3 I s o g j» « ^ [ 6D ^ tL d £ ^ i S _" -s U 3 ; m £ J <« P. : o = :S bo £ o 2 ffl m S ■2 -a- 6 6 43 -S a B a 4i6 TESTS OF GAS-BUENEES. reallj' contains the key to the whole subject of the use of gas for heating as well as for lighting.* In fact, light-giving and heat-giving qualities are very closely allied, and for some kinds of apparatus (where, for instance, radiant heat is required) are identical, although this does not seem to have been always recognized. Probably, in the future, more will be done with burners of the incandescent type used in heating appliances. On account of the value of these tests, and of the importance of accurate information on this subject, we have inserted at pp. 414, 415, a table giving the average results obtained by Messrs. Dibdin and Foster in their trials of different forms of burners. The following table and diagram (Fig. 255) are taken from Mr. W. Denny's paper, " On Cooking and Heating by Gas," as they illustrate a very interesting point. They record the results of some experiments made on the economy of burning gas for illuminating purposes at a low pressure. The curve (Fig. 255) shows the results graphically, and " they prove," as Mr. Denny says, " very clearly that the efficiency, as measured by the candle power of the light produced brought to a common consumption rate of 5 cubic feet per hour, varies in a ratio inversely to the pressure at which the gas is consumed. Doubtless a similar economical principle applies to the consumption of gas for heating and cooking purposes." Fig. 255. No. 5 Bray' 8 Burner, tested at Dumharton Gas Works, December 22, 1880. Pressure in Inches of Water. Consumption in Cubic Feet per Hour. Illuminatingr Power in Standard Candles. Illuminating Power with Consumption reduced to 5 Cubic Feet per Hour. 0-3 0.5 0.9 1.6 2.00 4.8s 5-35 8.0 II. 14.8 17-4 18.0 20.0 20.0 18.0 16.8 The illuminating power of the gas — tested under the most favourable conditions, in a large burner, No. 8, at o. 5 inch of pressure — was found to be 29. 3 caudles for a consumption of 5 cubic feet per hour. Gas stoves without chimneys — that is, those from which the products of the combustion of the gas are allowed to escape into the atmosphere of the * See also " On the Eoonomica Combuetlon of Coal-gas, ' 'by Dr. W. Wallace, " Proc. Phil. Soc. Glasgow,' 'vol. ix. p. 57. ADAMS' GAS STOVE. 417 room which is being heated — are fundamentally wrong, and are used only where health is sacrificed to economy of gas. Of stoves which provide luminous flames, or a source of radiant heat as well as a supply of fresh-heated air, those of Adams and Fletcher may be taken as examples ; while of the numerous stoves which merely supply heated air, those of Wright, Dr. Bond, and Schonheyder will serve as specimens. Gas Stoves with Radiating Burners. — In Dr. Adams' patent stove, shown in section in Fig. 256, a mixture of gas and air is burned in a series of E E 4i8 FLETCHER'S GAS STOVjS. fire-elay burners, or atmopyres, similar to those first introduced in Hof mann's combustion apparatus, used in chemical laboratories. These burners, c c, are Fig. 258 Fio, cylindrical in shape, and are pierced radially with numerous small holes, through which the gas and air issue. The burners are arranged upon a tray, which is drawn forward for lighting, so that the burners are lighted in the air outside the stove, and an accumulation of gas inside is prevented. In a very short time the burners become red hot, and a small supply of gas then sufiBces to maintain this temperature. Being placed behind a glass or mica panel, the radiation from the mass of red-hot brick burners is made available, while the hot products of combustion are passed over a considerable amount of surface formed by sheet-iron partitions, the other side of which is traversed by the air which is being heated. The waste hot gases are allowed to escape by a chimney g at about 240° F., this being the temperature necessary to produce an effective draught without danger of carbonic acid and carbonic oxide being returned to the chamber by regurgitation, and a supply of fresh air, which may be drawn from outside the house by the pipe A a, is heated to from 150° to 200° F. above the outside temperature, at the rate of about 200 cubic feet of air per cubic foot of gas burned per hour. The earlier form of the stove is shown in Fig. 257. Fletcher's gas stove, or " gas fire," as he calls it, Figs. 258-260, makes IXETCHEE'S GAS FIEE. 419 ■use of simple illuminating flames from ordinary burners for the supply of radiant heat, and causes the hot products of combustion to ascend in contact with vertical tubes, which are thus heated, and induce a current of air through them, the air being delivered at the top heated. In Fig. 260 the most recent modification of this stove is represented, where Fig. 260. the radiant heat from ignited asbestos, or from an iron fret, seen in the lower •part of the engraving, is combined with the system of warming by hot air shown in Fig. 259 ; the stove with asbestos is better adapted for a sitting-room. Fig. 261 shows the external appearance of one of the ventilating gas- ieating stoves made by Messrs. Wright, of Birmingham. In it, as in the E E 2 420 STOVES, WRIGHT AND BQKD. BOND'S STOVES. 421 "Euthermic" stoves of Dr. Bond, of Gloucester, Figs. 262-267, the gas is admitted through a Bunsen mixer to a perforated ring burner, which is Fig. 264. Fig. 265. Fio. 266. Fia. 267. ^temnnniwit^ a- 1 Ty placed at the bottom of the stove and in the centre. In Wright's stove, the burner is situated a small distance from the floor within the stove, which is perhaps better than having it between the bottom of the stove and' the floor 422 SCHONHEYDEK'S GAS STOVE, Fig. 268. SN»tNN»'N«S»\>«S«JN«)«N0N«NWS««<«S«!«5^NS^^ Plate )V SHOWINO RISE OF TEMPERATURE WITH PRODUCTS OF COMBUSTION THROWN INTO ROOM. 1° ■"' 1 3^ > ^ . cof' ,jl^;^J*<'''''^ ■ '/^ ! »' ^y r ■" ir" -ta" 4/ / ■ J^ ^ y , */ V 7 \^/ M y MINUTES OCCUPIED IN RAISING TEMPERATURE. Tn -facepaffe- 422 Plate V \ 1 1 \% I 1 1 1 1 w\ - \ \| 'I* \ |i 11 \ 4 1 ^ \^ 1 1 ^\| ' Ts • \ " 1 % 1 % 1 o 1 o 1 C: Ic 1 % 1» B u \% I 5 ^ t I ft 1° "4 « 1 1 ft 1 9 > 6 2 ^ \ is 1^ 11 ft 1 1 "* u ■ ft \ r '- 5 l| \ 1 > \ 1 ft ll At ■ Vl k I ^ V 5* V r \ ;• ? V 1^ La 1 fc — -» — 1 f \ TEMPERATURE INSIDE EXPERIMENTAL ROOM. To follow Plir Plato n RISE ABOVE INITIAL TEMPBE. |N 80 WINS. T» follow RY PlakVU \ i fi 3 i s 5 '. s i g J \ \ t^ s. V" 'V". ; L : 51 \ ^ e- \ * \ ^ \<^ a \ 1 V V \ \ \ \ < z z 9 O H H m M S o IS M s s i5 * 5 :f TEMPERATURE INSIDE EXPERIMENTAL ROOM. To follow PIW TESTS OF EFFICIENCY OF GAS STOVES. 423 as in Dr. Bond's stove. The hot gases ascend in contact with a vertical air shaft B, Fig. 262, tapered outwards towards the top, and then descend through a series of small tubes d, Fig. 262, arranged round the main cylin- drical casing of the stove, finally passing out by a flue or chimney i. Dr. Bond has introduced some improvements in details of construction in his stoves, and in particular has an alternative opening to the chimney at the top of his stove regulated by a valve or damper h, Fig. 262, by means of which a much more rapid combustion can be carried on, and varying conditions of chimney draught can be met. The stove designed by Mr. Schonheyder, Fig. 268, is of more elaborate construction than either of the foregoing, on account of its being arranged to provide means of ventilation as well as heating. The products of the combustion of one or more gas-jets, which may be luminous and set behind glass in order to give light, are conducted through passages in the stove to the chimney, the air, which is supplied from the outside of the house or building, being heated in its passage through channels formed by the heated surfaces. A valve and discharge are provided at the foot of the stove, by which the air of the room, when cooled and falling to the floor-level, can be withdrawn by the chimney; but the stove can be used for heating without changing the air of a room. The results of comparative tests of the eflaciency of these and other gas stoves will be found in the Reports of the various gas exhibitions already referred to ; those carried out at the Glasgow Exhibition will be found in the tables at pp. 424, 425. Some interesting comparative tests, which included the results from an ordinary coal fire and those from gas fires, as well as from several kinds of stoves, were carried out by Mr. W. Denny,* of Dumbarton, who set out the results graphically in a series of dia- grams (Plates IV. to VII.). Mr. Danny's results are given in the follow- ing table : — RISE OF TEMPERATURE IN 8o MINUTES IN A ROOM Io| FEET X I2| FEET ■XII FEET = 1,415 CUBIC FEET. Initial Tempera. ture. Rise. Outside Ttmperature. Consump. tion. Cubic Ft. Waddell & Main's hall stoye Coal firei Imperial stove .... Do. .... Dr. Adams' stove Verity's (ire — white asbestos. Do. — red do. Hislop's asbestos fiie . Do. do. Do. do. Do. do. Do. do. 56° F. 44 55 52 52 54 S3 Ik 51 474 44 11.9° F. 10.3 II. 10.4 95 2.4 2.2 1-5 1-9 2.1 3-0 4-3 54° to 52.i° F. 39^ 5oi 424 46 49 51 56 to 53 52k to 54 42 44 36 I7-S 19.2 12.8 13-6 21-5 21-5 22.5 21. 1 39-2 21-5 32.2 ^ N.B. — It is to be noted that the efficiency of the coal fire in raising temperature is really lower than it appears, and very probably considerably lower, owing to the initial temperature of the room in its case being on the average abont ten degrees lower than in the case of thu gas fires, with which it is compared. The deductions drawn from this table in the paper are, therefore, too favourable to the coal fire. In all these results, however, there is merely a comparison instituted between the quantities of fuel required by the various heating apparatus, and the time taken by each to produce a given rise of temperature in a room. To » See " On Cooking and Heating by Gas," by W. Denny (J. Menzies & Co., Glasgow and Edinburgh). 424 TABLE OF TESTS OF GAS-HEATING STOVES Name of Stove, with Name of Maker or Agent. Household coal . 9.00 8.26 Dr. Adams' stove Dr Bond's eu- thermio stove Cox's ventilating stove George's patent calorigen Writyht's imperial Btuve Waddell's stove . Gillin^ham's heat 16,0 radiator Novel gas fire (Chas. Wilson) si us. ■c S Heating Results, Heat Units per Cubic Foot of Gas consumed. A. 711.68 58.66 ■38.611 118.90 B. o.| eu'Ji > ^ 546.64 463.71 4T4.31 G. Ventilation Waste Products. Outlet Ventilation or Air extracted from Uooms by Stoves. A'. B'. C 3 3 57-9" 51-50 483 5c 60.40 151 60 305 90 none (a) 513.60 471.60 18.90 58.90 £ So i o" <; 00 -J *^ III 9 m ID 1 O'.s; I it *3 I «-*. C C 122" 202° 238° not a tain not a tail 8.58 sppr- able sccr- able D'. ; po l.g SI. '-< a i OB'S ! 3 £ ' O QJ 3-S3 S.58 18 33 8.58 24.92 8.58 8.58 8.58 8.58 8.58 S.58 9.18 34 57 6.90 not aseer- t.am. able A!!. < o a .2 3 = £ 26.91 33-50 17.76 none; busti from from no ou tion 15.48 B». C\ 1 o-a s-26 6 70 2.66 air fo on not room, outsid tiet ve so cau 2.66 £ Pi 80.30 100.00 39.70 r com- drawn but e, so ntila* Bcd 41.20 Note —In the two figures marked (a) in Col. F, a deduction is made of the AT GLASGOW EXHIBITION, OCTOBER 1880. 425 licsults. Power of Stuve warmin? A r from 32° to 72° P. per Cubic Foot of Gas burned. A'. 1138.5 779.5 6o2.o 582.6 683.1 722.64 beg °s none none S02.63 450.1 502.63 C. 1,138.5 779.6 602.0 5S£.6 683.: Ifi. s 5 8 52.8 51.2 irore air is vitiated than is w.nrmed Inlet Ventilation or Fresh- warmed Air passiuf^ thi-ouKli Stove Duets into Rooms. 6 u a — |3 o S U hi B«. gfei 35 c* K >-. Tl -s ,2 g % Em a u II F tlO'O ce s b fc 13 J3 % (1h rX D*. 28 159" , 14.010-5 1,000 75 two ducts 200" 219° 989.7 I.7S4-8 82.48 19493 1,381.0 167.19 864.8 19.4 16.7 80.57 Piconomic Results. Units per cwt. of Coal per Cubic Koot of Gas and Kelutive Cost of eacb. A'. a C S S .S g g.^ S 1,000,000 1,000,000 I 000,000 I 000,000 B5. g ui g « Qj b sal Z a ^ {J Q> O fO ^ .^ ?, CO 1,249.60 1,836.05 2,156 52 2.413-6; C5. X. d o lofo.oo D5. 4 6£ i.oo 6 8? 7 -fOf 8 10 6,596.30 2,118.80 8 4^ I 83 24 2 7 9 resultb in losg to eon- sumcr Bemarks. This result is for lieat developed in warming and ventilating. In ordi- nary open fires of improved type, the heat useful for warming purposes does not exceed from 15 to 35 per Eer cent, of the total in the coal, the alance (leas deduction for imperfect combustion) passing away up the chimney, and so inducing ventilation from the room. Some close stoves are said to utilize 95 per cent, of heat for warming alone. Temperature of products too low; also, if ducts are used to introduce air from outside, waste products arc not drawn from room ; otherwise a most excel- lent stove. The double numbers, columns A' to D^ and A2 to L^, are with throttle- valve, shut and open. Heating power taken with it shut. An excelleni stove. Stove heated by white-flame burner; neat and well finished. Column C eoTrc t, but 1> prob.ibly over the actual. Air lor combustion must come from outtide— so units in D lost for ventilation, thus accounting for cost of fuel in t^ notwithstanding number in C. Flue arrangements useful in exposed situdlions. Similar to eutherniic stuve, but with- out throttle-valve, the want of which, together with inferior light- ing arrangement, might, without careful attention, induce explosion ; also temperature of waste products too low; otherwise a good stove. This stove has no flue to carry off combustion gases, so cannot provide ventilation, and vitiates a great pro- portion of the air it can warm 40 F. 'ihe lower figures in columns B^, C', and 1)5 show the relative cost of tuel bad a flue bten provided, takmg pro- portion per E. , A flueless and so-called condensing stove, hpated by single argand bur- ner. Makers state that flues can be supplied, but no apparent provision made lor such in apparatus tested. vitiates more air than it can warm 40° F., but sample tested did not appear suited lor Scolch gas. Thin fire, intended to be placed in an ordinary grate, was placed bodily in test-casing or room, and so tested only for total heat developed, botli for warming and ventilating, the re- lative proportion being probably simi- lar to that of an ordinary open fire. units neeeseary to carry off the air rendered impure by the combustion gases. 426 GAS COOKING-STOVES. estimate the comparative cost of these various appliances merely in terms of the fuel used by them would not convey an accurate notion of their relative value. Estimates have been made by Mr. J. E. Napier, in the paper re- GAS COOKING-STOVES. 427 f erred to supra ; by Dr. Wallace ;* by Mr. T. Metcher, of Warrington, in his paper on " Economy of Fuel in Domestic Operations ; " and by Mr. T. Box, in his " Practical Treatise on Heat ; " but, in the main, these estimates do not take into account the useful effect obtained in practice (and not merely in experiment), the proportion of waste in each case, or the elements of cost, in the shape of labour, and trouble which accompany the use of coal and are absent from that of gas. In domestic affairs, the lessened labour and trouble, in spite of a more expensive fuel, will often turn the scale in favour of heating by gas ; but, for heavy and continuous heating work, it is certain that ordinary illuminating gas cannot, from its cost, compete with coal. Fio. 271. Where, however, producer gas or water gas can be applied and used, the case is very different, and it is probable that even domestic heating by gas of this quality will be found to be more economical than where coal is burned in stoves, the economy of heating in manufacturing operations by means of producer gas having been fully proved. Gas Cooking- stoves. — These are arranged in various ways as to the burners used, and the application of the heat to the food cooked in them. Some, like those of Wright, Fletrher, and others, make use entirely of Bunsen or non-luminous flame burners. Others, such as Waddell are to be conducted, the meat is cooked by 'j^- ^ ^ contact with the hot gases, and the condi- ■tions of an oven are approximated, the difference being that in a close oven the meat is preserved from contact with any- F16. 274. thing but hot air, and the vapours given off from the meat itself; whilst in gas cooking- stoves of this kind it is in contact with the gases given off from the always somewhat imperfect combustion of the gas fuel, besides other vapours. Lumi- nous jets and incan- descent burners supply radiant-heat rays,^hich are req\iired in the operation of roasting; and of the two kinds of stoves having radi- ating burners, the one which preserves the meat from contact with the hot products of combustion while it is being roasted, is preferable from a theoretical point of view. In genei-al appearance, most of the gas cooking- stoves resemble each other — they consist of an iron casing, with one or more doors giving access to the body of the stove ; a perforated top, having ring or other burners at 43° ADAMS' GAS COOKING-STOVE. vari ous points ; and often between the body of the stove or " oven " and the top, there is a narrow space in which trays can be placed. The oven'is divided by shelves, and burners or gas jets are placed round the sides near the bottom. These jets are luminous in the stoves of R. & A. Main, Fig. 269, non-illuminating in the majority of other designs, such as Wright's, Fig. 270, or Fletcher's, Figs. 271, 272. In some cases, as in Wright's reflector cooker. Fig. C73, luminous jets are used in combination with reflectors so as to concentrate the radiant-heat rays upon the meat being roasted ; whilst in Fletcher's, Verity's, and the TESTS OF GAS COOKING-STOVES. 4? I Retort Gas Stove Company's stoves, special burners are used for the pur- pose of developing a greater degree of heat from the combustion of the gas. All gas cooking-stoves should be lined with fire-brick or other non- conducting material, and should have provision for carrying ofi' the gases and vapours to a chimney or ventilating shaft. This should include the top of the stove as well as the body, but, except in the case of Dr. Adams' cooking- .stove, this does not seem to have been attended to. The Adams cooking-stove, illustrated in Figs. 274, 275, is the only one introduced, as yet, in which, along with the use of incandescent burners, the hot products of combustion are kept from contact with the food being cooked, and are used for oven-heating, boiling, &c., as in close cooking ranges con- structed for coal firing. There is certainly novelty and merit in this system of construction as applied to gas cooking-stoves. In testing the efficiency of gas cooking-stoves, it is usual to ascertain the maximum temperature reached and maintained by means of a recorded con- sumption of gas. The practical test of cooking some meat of various kinds is also resorted to ; but there are no records of tests in which the eflects due to convection and to radiation are discriminated. The following table and that on p. 432 give the results of the tests carried out at Glasgow, and at the Exhibition in London in 1882-83. No doubt, the chemical effects on food which are includv^d, in the term " cooking '/ are, in the main, due to elevation of temperature ; but there is also a difference in the result pro- duced by different qualities of heat, as may be witnessed to by the difference between a baked and a roasted joint. Extracts Jrom PrcicticaJ. Cooking Tests^ and Tests for Heating up and Loss by Radiation, made hy Examiners at Gas Exhibition, Glasgow, October 1880. » i lb. of tove. ncrease inute. J g| ill Maker and Name of Stove. Condition of Food cooked. 3"* r 1^ li 11 1 t-!^ is a) IE CO Us a s £ 5I III -X h. m. cut), ft. Main's " universal domestic" Meat well d ne . 1 2.5J 22.60 1.88 27.00 0.270 0.0 '57 Bread Wilson, of Leeds, " eclipse " gis kitchener Well done 2 17 30.00 1.25 20.50 0.260 0.013 19 4 Wright's " gas cooker,'' No. 492 Excellent I 304 12.00 1. 00 11.66 0.120 0010 320 22.6 Cox's " save all " j» 2 49 23.80 1.48 8.88 0.139 0015 ,, '■ dispaich " . )» 2 20 17.50 J -45 20.40 0.009 14.0 14.0 Beverley & Wil.le's "Leeds Meat well done . I 55 29.06 2.42 20.70 0.015 family kitchener '' Bread „ Billing & Co.'s "snn-dial" »» )I 2 64 21.71 1. 81 Fletcher .... Meat underdone I 53 '9-5° 243 Bread well done In connection with both heating and cooking stoves using gas fuel, there is a matter of some interest. which offers a field for investigation — viz. the proportions employed in the various so-called " Bunsen " mixers or induction jets, for producing the mixture of gas and air used in Bunsen or non-lumin- ous flames. There exists no information as to the influence exerted by the shape and dimensions of the gas nozzle and of the delivery tube for the 432 TESTS OF GAS COOKING-STOVES. t O I— ( H H 12; M W o 00 00 00 |2i o O 1-:! o m p^ a ^ X ^ w f^ C! ^ ^ W 1— 1 M a r/j <1 PR r^ H pt) H Average Tempera. ture in Oven. Fahr. iriino WTJIO OOroO-^ONONO^OOvOMQ '-' VO O^00 in 00 u-lQO -"i- t^ U-) r^OO ONVO m invO VD vO ^ u-l rn ro M ro f^ M ro f*^ CO ro f^ fO ro ro rn r*-) ^ M m "sh fn Time per Pound. mins. 00 f^OO M ror^ N mmvO «-< 'tvo rN.W0OON00MMTfrf Time Roast- ing. h. m. « M N t^ a^oo u-)a>"Smo ONW M lot^o r^"^o •-' Gas per Pound of Joint. cub. ft.. M h^ N N «ci«NW««fO«rO«fOfOMNrnMMr^N Gas per Hour. cub. ft. 00 u-lOO vO d^ -^ OMninM'-'NHt...oa^OOOmQOONinmO vd d^ d\ d d dvod d»pod d d^N « d dvrodv>-^int-J Gas con- sumed in Boasting. cub. ft. 0NO\0 M l-l « 00 fOininNNONM o^oo imn ro t^ f^\o m m r^ 00 MC^'-)■^d^^ Percent- age of J pint coolied. N ON OS i^t^ovOvqmqvom"cjooo>i>ooc>roqO'*^ ■^ i^d'inint^i^t-J'-IvdintC.h^NuSoySNt^i^N ».* \0 t^ r^ t^ t^ t^oo t^ t^ l^ t^ t^ r^vo t^ t-^00 r^ t-^oo t-i in -^vo "i-vo t^ ^00 ^000 N win.«tm« t^ OvOO t^ ^ fnoO 00 t^OO 00 t^OO Ov 0^ O^CO 00 00 00 Ov Inlet Area. sq. ins. m M N m in\o voOt^OOo"^ininOOOOOt^ tC, « N fn rooo 00 00 vd - « -^vd •S^^^'jS'S d fn m M Hi M h^ f^ rovo i-t TTVO « -"i- ■*■*■* ^ Tj- -^vo *-^ Jet A>ea. sq. ins. d d d vO mvo \0 ■- I.N OVVO in^OVNl^Nr^— P»OvO ^ vo 1 mvo vo vo vo ro m ^vo r^^*-. I-I rnmii poi-i fi d 'do d d d d d d d d d d d d d d d « d iM 00 m vOvooOoooOf^inON rovo r^r^r-.inO Q O ^O m f^ m ^ ^vo vot^ONPDPO^^-* mv5 v5 vo 00 i-i ci «MNNNNNcor^PO(Of^MrnrnrOP^f^f^in to bo . - 1 Eureka Artisan, No. 496 Metropolitan, No. 8 No. 201A Nonpareil, No. 55 (new) Universal Domestic, JSTo. ; (plain gas) . Dttto (atraosphenc ga-') . Eureka, No. 410 . Ditto .... Metrrtpolitan, No. 9 Ditto (new) , NimpaVeil, No. 56 . Eclipse .... Paragon, No. 624 . Fletcher's Bange, No. 3 . Nonpareil, No. 56 (new) Ditto, No. 16 . Ditto (backward jets only) Ditto (forward jets only) Metropolitan, No. 10 Nonpareil, No. 16 (new) Ditto (forward jets only) Ditto (backward jets only) Beverley & Wylde's, Sydiiev Nonpareil, No. 57 (new) H . . . _ John Wright & Co. H. & C. Davis & Co. West Bros. . General Gas Liglitmg and Healing Apparatus Co. Waddell & Main . Ditto .... John Wright & Co. . Ditto .... H. & C. Davis & Co. . Di.to . . . Gener»l GasLightiDg,& -..Co Chas. Wilson & S.ms E. Liddaway & Sons . Deane & Co. General Gas Lighting,&c.,Co Ditto . Ditto . Ditto .... H. & C. Davis & Co. . GeneriilGiisLightiiig,&c ,Co Ditto .... Ditto .... "William Stobba . General Gas Lighfing,&c .Co ». M fO ■+ "1 vo r^oo CT> « 2 « * ^"£ I^ « « S S « J? M PEOPOKTIONS OF BUNSEN MIXEES. 433 mixture of gas and air, and the effect on the composition of the mixture produced by different ratios of area of gas to that of air inlet used at varying pressures of gas. The practice in the construction of Bunsen mixers, which are exhibited in Figs. 276-279, shows that there is no rule or formula to guide Fig. 276. Fig. 277. in fixing proportions under the ordinary variations of pressure in towns. The sizes of some were investigated by Mr. W. Denny, who has given the following results :* — Mixer etrplojed in Area of Gas Nozzle. A. Square iDchea. Area of Minimum Air Space. B. Sqnare Inches. Ratio of li. toA. Gas fires — HIkIop's (Fi?. 276) . Verity's (Fis;. 277) Heating-stoves — A'lams' Wiight's imperial (Fig. 278; Cooking-stove — MHin's (Fig. 279) .0164 ■0338 .0014 .0167 .0044 1.230 0.368 0053 0.109 0.242 75.00 10.89 57.86 6-53 55.00 lixit Gases and Soot. — A number of open stoves were tested at the Kensington Smoke Abatement Exhibition (188 1), and a valuable chemical report on the results was drawn up by Professor W. C. Eoberts, F.R.S, * " On Cooking and Heating by Gas." 434 EXAMINATION OF EXIT GASES AND SOOT. Peclet's early experiments (1828) had dealt with too small fractions of flue gases to be- more than indicative. Forty years later {Bull. Soc. Ind. Mul- house [Memoires] ; Paris: Lacroix, 1875) Scheurer-Kestner and Meunier showed that, in boiler furnaces, even with a 50 per cent, excess of air, the products of combustion always contained imperfectly burned compounds, only 80 per cent, of the hydrogen being, in fact, consumed. They also observed that, when the layer of incandescent fuel is thin, the unburnt carbon in the gas is more apt to be present as hydrocarbons than as carbonic oxide. Roberts draws attention to Cailletet's discovery that, if the gaseous products of combustion be collected very near the fuel, they will contain more carbonic oxide than when cold — that gas, in fact, combining with oxygen during the act of cooling. The flue gases in the South Kensington experiments were in each case collected at a distance of 10 feet from the burning fuel ; and the thermometer and anemometer were inserted close to the point of collection. The chemical arrangements included: (i) an asbestos filtering tube, 84 per cent, of the increase in weight of which represented soot ; (2) a drying apparatus containing calcic chloride ; (3) soda-lime tubes to collect carbonic acid ; (4) a combustion apparatus, to burn completely any now remaining hydrocarbons and carbonic oxide; (s) a drying tube; (6) soda- lime tubes. The results of eighty-five cases examined show that the weight of com- pletely burned carbon is to that present in the form of carbonic oxide or hydrocarbons as 1,000:4 to 1,000:375. There were, however, only nine cases in which a ratio of 1,000 : 200 was exceeded, and but three in which the ratio was less than 1,000 : 10. According to Scheurer-Kestner's experiments (foe. ctV.), the amount of carbon in soot seldom exceeds'! per cent, of that in the fuel burned. Soot, especially that which is deposited near to a furnace, is always rich in heavy tarry hydrocarbons in addition to actual carbon ; and it invariably, in such positions, contains more light ash, carried forward by the draught. The tables given at pp. 435-438 contain a record of the experimental results. Heating by Means of Channels or Hues. — The method of applying heat by means of flues, which is one of the most ancient, having been used by the Romans for heating their baths, is still often practised in hot-houses. The hot gases and smoke produced in a grate placed at a lower level and on the outside of the space to be heated are conducted through a system of flues under the floor, where they part with their heat and then escape by the chimney. Unfortunately, this mode of applying heat, certainly the best adapted for dwellings, can only be managed in the lowest floor of the house, and even there with difficulty. Great care must be taken to surround the lower part of the flue with rubbish or some non-conducting substance, so as to prevent any loss of heat in that direction. The position of the fire with reference to the area to be heated forms the only essential difference between this method of neating and that with the close stove. Heating by Means of Hot Air. — When greater security, want of space, or other considerations render it desirable to remove the stove to a distance from the apartments to be heated, the necessary quantity of air can be warmed in another part of the building, and conducted by air-flues into the different rooms. Heating by hot air is the designation exclusively given to this method, although it applies with equal propriety to many of the others, the air being in nearly every case the medium through which the heat ultimately reaches its destination. When the supply of waimed air is abundant, and is trans- CHEMICAL EXAMINATION OF EXIT OASES. 435 rn W l> ;g p s= H IS OQ ^ P ? ? «1 tS^ 03 1 H c -t! ■« a H w W '^^ H i (^ e» <^ O « l-H -a a f w w r\ o !? o 1 w 1-1 H n ^ •J W P4 il^llfl - ^3, 8 8.>8^S,^c8>S . o 1 p^ tv &8 s.| 8, as, W M ■^ drnddrncJ'^iN ' A ci M rn »n eJ ci m «W-iW ^M H^-«. = 0^ |«. rr. ^o^o "^^^.fne^ rom tr,m Th mvo ro "^« fn Weigh fMatt etaine yAsbe tos in Graine 8 m in ?3- 3- ?ls-i5SI~? H § mm ddddddod O do do 5, ^o od"- g-S = = >.igoS*.i.ss To eve i,cxx3 Par Carbon as there ar Hydrogen and comb with Car in the gas State 7 •+ fO M , t>.\0 , N t^ m ■--"'•si 1 ss- ■"1 -"1 '"" ►.•§ S ?> 3 h o go « So" + (ri M Tf- ^»o fn m fvvo ^ t^\o tn &l-o'^^' 1 1 fa 'li ■ ature of 5 ••=2 Is 3 , •ill ig ^■11 a ^< is hn •rg -^ ••S'S '■s • • ^- c S ,2 1 < ^ ."=■£ .% . ^ -a '*S tea s • «• 1 ■s •§ i s. ■ll ■1 -1 ■ §■ 1 i-si 1 • • 115- .-& * t ' •a ■s.2§ e •§ s ^ s . 1 ■g • ■ ■>=^ |-s|--^;.|-^ h c .a go • •fs'^-^ t Hi ilfi 111, OH n OSS'"! OtVOfci o: Ph« m«!H E-5 1 . |!5 -3 •a 1 If 5 1 1 .2 1 i' Ill ilr' 6 ■ a- • a ! ■ • ll . •■it-li id P's -li. fa g^a ^= hbW H Srja H^f.-^ p-i l'|.ai « M ^ * « ion M fOM'*« Mm tn « lO tm-* MM 1=1 - M « m in^ w o t? !23 <§- 02 i-i 3 1 02 O pa Total Aver- age Smoke Shade Clark). 10 CO >- o tn a\ n tn ■* •* m H M Oi «eo n m m mrouT^w mcnet ^ a • « » ■* m N N H » N ■* — -w ti §ilg <» ^ «noo\D « oja^ ^ a M m« fO« mmmN N ■* « « ro M m m « m *" S'a 9 Weigh of Matt retaine by Asbe tosin Grains 8 loioomooomiom m m m 'SSS'2'SS-S'E-?2 S 5S8^^ O a S'ffS"^ ?r doddddddod 1 O 6 6 6 6 1 ■SoVS'S-9. To every i,ooo Parts Carbon as C there are o Hydrogen ft and combin with Carbon the Gascon State 7 Ov ■*« m *o 03 -O 00 M i In. H OSH *o 'O ffff'SR To every i.ooo Parts of Carbon as CO, there are of Carbon asC,H + 00 6 »J °'S8S-'-"S'E-^? ■H H ■1 S 1 !•■• "S g £ 1 "3 ■« § 1 fo • • • 1 S s d £| •^ ■s 13 ■s g >< s g ^ •« "a r o . CQI — l-t ■■■! i 1 . ." =1 & l\jf.r2i eg- S c H 1. t— 3 1— I .... 6 o • d .5 . ^ 1 u. ■3 < ifll 1 t £ 1 O 5- n hQ^c^ Eua &iw5:*c4 >s '■ < tePn^ai < No. of Test- ing- room. 2 c* mw ■♦N "^lomw ro ■i-fr, ■,^lr^ m "* ,„.. ■* RSS'ft^giS-S-i?^ m "TO t^ m in in (n % -g CHEMICAL EXAMINATION OF EXIT GASES. 437 1 e 3 s S o e g eg- I Total Aver- age Smoke Shade (Mr. Clark). 10 00 « N ■««■ m t^ rocT* wi t% moOO^ ciTt-m M CO H H M ■^^ m « m mooOM N«m Coal burnt per Hour. 9 M H « ■*• mm mm lo ■*« « M m m ■* Weight of Matter retained by Asbes- tos in Grains. 8 §§ ^1 d d OioO»nin omomo S8SS? S'5'?S8 ddddo ddddd S do 6 d do do ^ d every 3 Parts on as C re are o rogen fr combin Carbon Gaseou State 7 inMONm* ooOO^m-d- mifH^^. NOiocim "^wmp m- M txO* (*1 "1 * '-* ss- M M 4 . . . . . . . fc, o * ' o ? •a ^ s g Sg A ° Sa tr '^ II II ^^ 1 1 •a "a ■" »- s 1 -g-s ■s 1 i 1 Description. 4 1 1 *f t: k. ^ o ;: 'S M « i •s 1 CD § is =^ ■§! •s ■2 2 ■? g-a .3 if LIS ..■g.5'3 •• 'I 1 If I^Ji jfi; 1 iiitliS- (34 Qco >>A « 6 «! a ZZ » fiH«Q|3 •5 ■ s o f? W CO o " -1 • Kir - o "^1 111 5 1 Us 1 I'l No. of Test- ing- room. 2 ■* m ■*■ mm ro ■* ■* m "l 1 438 CHEMICAL EXAMINATION OF EXIT GASES. 000 Qpomt^io C30OOM eiioOioOO>n'4- d«d HO'i-dd dddrn Meidndddw 5FI H«MfO* wwOcn WW. mw mvo p* ^ 43 oi'c) n 13 I I 02 o 02 02 W . H S 0««mOOOV) oooggSoooo o d d-t3-f3 d d d d ■ , g> ro m c 1 I ■* "O r 6&5 i5 " 2 a —r O S =- S " 0> — is d v^ o J= " S OP'S ^■25! 0}" ^3 S o g- P » " g S^ 35 44 rt CJ 9 o " K3 fc > t* M 3 > a'3! islsrs <1 o2 o: a o a> ass e Bi m . fO p _ 5 ; ! ■< B-«IOOC. d s ■5" '^ B aaWsB o Ha n o>. id QtBXfs'BS . .^ a s -a* lilt -2 gs5 w.S ^ sa< ■5*i = o« r)«M N-^-^wio inin-^fo fninminminiorotow 1 IS. f»i M CI .^ ii^«o Mfnmr^ ooONf*i >nvo <> cr> i > js5sg la s-gssa "2 ' bo no .^.^ q)«-«'g ts c ' S^ — "S ® aa?aT3 g-- §S-S Spb^S s'SS -S..* « S S "1 HEATING BY HOT AIE. 439 mitted to the apartments with a certain amount of force by machinery, no extra outlet for the vitiated air is necessary, sufficient ventilation being afforded, in small rooms which are not overcrowded with inmates, by the un- avoidable crevices in windows and doors. Special means of ventilation must be provided for crowded apartments. With a view to economize the heat of the air which has already circulated once through the apartments, two methods have been proposed. The one consists in reconducting the air to the heating surface of the stove, and again transmitting it to the spaces to be warmed; this practice is decidedly objectionable, as the air which has once passed through the lungs is no longer fit to support respiration. It is far better to conduct it to the ash-pit of the stove to supply oxygen to the fuel, where the higher temperature, as compared with the external atmo- sphere,, which it still retains, will more than compensate for the lesser pro- portion of oxygen which is present. If i lb. of air-dried wood requires 5 lbs. — 123 cubic feet of air at 0° C. for combustion, and if, according to Rumford, 26 lbs. of water can be heated by it to 100° C, or 4 x 26 = 104 lbs. of air to 100° C, or =5^0 lbs. of air to 20° C; then the tempera/ ture of 20° (instead of 0°), at which, in this instance, the air is furnished I X i; to the fire, will correspond with a consumption of - — = nearly 0.0 1 lb. of wood, which must consequently be saved. This saving of i per cent., or something more, when the temperature exceeds 20° C. (68° F.), is too small to warrant any particular attention, and it is found judicious in practice to combine the two methods. The airj which has circulated for some time, may be allowed access to the hearth, and is replaced by air from without, the heating of which will then cost just as much as has been saved by employing the other for feeding the fire. Supposing that proper ventilation can be kept up in a room by means of doors and windows, the first method will necessarily be highly advantageous; the warm air streaming in will force out that already in the room, and thus produce a state of things in which the tendency of the external air to force its way through the crevices will cease with all its attendant disadvantages. It is quite certain that the loss occasioned by supplying the fire with cold air is counterbalanced by the advantage gained. The method of heating by hot air is not desirable for buildings in which the number of rooms heated varies from day to day, because the proper relation between the dimensions of the stove and the supply of hot air cannot be easily accommo- dated to meet a fluctuating demand. In other respects, this method of heating is economical ; one stove only is required, and the fuel is more com- pletely consumed than if the same quantity were distributed in separate stoves ; lastly, the advantage of a uniform, equable heat, proceeding from the level of the floor, fully compensates for any loss occasioned by the transit of the hot air through the flues. Hot-air Stoves. — Two systems are adopted in constructing these hot- air stoves. In the one the smoke and hot gases are caused to circulate in an extensive series of metallic or stoneware flues, and the air to be warmed, supplied from the outside of the building, is conducted to the outside of these, where it absorbs heat from their surfaces and from the inner side of the case of the stove. In the other, the air to be warmed is conducted through metallic or stone-ware pipes, round which the flame and smoke are allowed to play ; the internal surface of the air-tubes is in this case the only source of heat. About 10 square feet of heating surface per lb. of coal consumed is found practically to work well in both systems. The forms of apparatus constructed by different inventors for heating 440 HOT-AIR STOVES. Fio. 280. the air are numerous. The following illustrations will give a general idea of this method of heating dwellings. Fig. 280 represents a lateral section of a series of cast-iron pipes, in the form of an inverted Y, set in brickwork, parallel with each other, over a furnace. The flame from the furnace, after travelling to the end of the angular vault of pipes through the Sue ^, returns through B, and passes back again to the chimney through C. Air from the exterior is supplied to the pipes through the flues N N, and the heated air collects in the chamber M. Other pipes may be inserted with iron cement, in the position indicated by the dotted lines, when they will form a por- tion of the upper flues B and C. The position of the pipes in this arrangement is such that the joints are weU protected by a body of masonry, and there is little danger of smoke from the fire mixing with the current of warm air. The lower side of the pipes, immedi- j ately above the fire, is apt to be too much heated, but this can be prevented by carrying a brick arch along the hottest part of the flue, between the flame and the pipes. The efiect of the apparatus is very much increased by employing pipes that are cast with longitudinal internal and external projections, when a larger surface of metal is exposed both to the fire and the air-current. Figs. 281, 282, 283, and 284 represent the hot-air stove of M. Duvoir, much used in large workshops and manufactories in France. Ren6 Kg. FiQ. 281 KENfi DUVOIR'S stoves. 441 281 is an elevation; Fig. 282, a section on the line a; a;' (Fig. 284); Fig. 283, a section on the line yt/ (Fig. 284) ; and Fig. 284, a horizontal section on »s' (Fig. 282). The fire is placed on a grate jr, surrounded by a cast-iron cylinder A, cased with tire-bricks to a certain height. The smoke descends Fig. 283. Fio. 284. simultaneously through the two rows of horizontal pipes B G D E F and B' C D' E' F', and rises again in the cylinder G before passing off by the chimney H. The air to be heated is conducted to the stove by the sub- terranean flues 1 1, ascends at the sides of the two cylinders and round the pipes, collecting at the top of the stove in the chamber .AT, whence it is dis- tributed to the different apartments. The pipes are all of cast iron, connected Fig. 285. 442 talabot's hot-aik stove. together with iron cement. The upper door to the fire-place d is used for the supply of fuel, whilst c serves for clearing the grate. Anthracite or coke may be burned, and these fuels are indeed preferable in this stove, as they do not produce so much smoke, and the pipes require less frequent cleansing. The fire is renewed every seven or eight hours. In order to assist the draught on first lighting the fire after the apparatus has been long out of use, a small additional fire-place is inserted in the cylinder G. The hot-air stoves employed at the Chambre des Deputes, in Paris, were constructed by MM. Rohaut and Musard, according to the plans of M. Talabot. They were found to answer perfectly, and continued in action several years without requiring repair. Two were generally placed together, the fires being in the centre, and the chambers containing the air-pipes on each side. Fig. 285 is a vertical section of a single stove on the line z'z' (Fig. 286). Fig. 286 is a vertical section on thB line y y' (Fig. 285 and Fig. 287); a vertical section on an undulating plane x al (Fig. 285). A is the fire-place, arched over at the top and perforated at B B for the escape of the flame and smoke, which, reverberating above and among the two upper rows of cast-iron pipe C, are forced by the solid brickwork, which fills up the spaces between the two lower layers, to make their escape in the direction of the arrows to an underground flue. The fire-place is about 3.3 feet long, 2 feet high, and i foot wide, and consumes 22 lbs. of coal per hour. The whole chamber, including the fire-place, is about 9 feet 9 inches long by 5 feet wide, and 6 feet 6 inches high. The air warmed by its passage through the horizontal pipes, which are between 6 and 7 inches in Fio. 286. Fig. 287. diameter, has no perceptible odour, very few of the pipes being so near the fire as to become red hot even when the draught is strong. Mr. C/on.stantIne states, however (see his treatise on Practical Ventilation and Warming, Churchills), that he found the drawback to the use of this form of stove| to be that the pipes frequently were burned through, and with a strong draught this might take .pl^ce in a few days. He consequently discarded its use in his work. The temperature of the escaping gases is low, although IMPROVED HOT-AIK STOVE. 443 the draught is good and the combustion very complete, even when the ash- FlG. 288. pits are nearly- closed. Much air finds its way through crevices in the brickwork into the chamber, and there is con- sequently no fear of smoke being mingled with the hot-air current. Internal ribs to the cast-iron pipes would increase the teating power of the apparatus. A hot-air stove, similar in prin- ciple jlo that used in the general Derbyshire Hos- pital, but some- what modified in the construction, is shown in Figs. 288 and 289. A cast-iron cylinder, or cockle, closed at one end, /, d, descending as low as the grate, is 1 inverted over quadrangular fire-place in the form of a hopper, and lined with fire-bricks. Fuel is introduced Piq_ 289. through the door D, and the smoke escapes through two long flues running the whole length of the furnace just above the fire at n n, and passing be- tween the external brick- work and the cylinder, heats the lower part of the latter before reach- ing an underground flue leading to the chimney ; rr are the handles of scrapers for cleaning the flues n n when they be- come choked with soot. A is the ash-pit. Fresh air is supplied from the outside of the building by a subterranean channel passing between the walls ^ff"^. A revolving cowl 444 constantine's convoluted stove. Via. 290. is attached to the entrance of this channel, the mouth of which is always presented to the wind. The cast-iron cylinder, J d, is encased with a sheet- iron envelope, a 6 c, in which are inserted a great number of sheet-iron pipes open at both ends, and terminating within about half an inch of the cast- iron cylinder. Fresh air from between K K first ascends into the space M, enters the tubes, and, coming in contact with the cylinder, is warmed, and escapes again through the upper series of tubes to the hot-air chamber, whence it is distributed over the building. These hot-air stoves cannot be economical, as little more than the radiant heat is employed in heating the air. Where only a moderate heat is required for a large body of air, the stoves with hori- zontal air-pipes will be found most useful ; their construction is simple, they admit of being easily cleaned or repaired, aRd are less costly than the others. The cold air, streaming simultaneously through a number of tubes, cools the smoke very eflfeetually, and prevents the tubes from acquiring an excessive heat. A much higher temperature is obtained with the same amount of fuel when the air-current is made to travel in •* a i i mgC^ an opposite direction to that of the smoke, uHHHpmH as in the stove of Kene Duvoir. I ^■Hll' Til ^^g®- 29° *° 294 illustrate the " con- ^HHyyyiUpF \ voluted stove " patented by Messrs. Joseph . ?^^^H^BIBII^^^^^ Constantino k Son, of Manchester, and ap- plied to the heating of large buildings, such as the Manchester Eoyal Exchange, Concert Hall, Pantechnicon, Theatre Royal, &c., and to suppljring hot air in the Arlington Street Turkish Baths in Glasgow and at other baths. Fig. 290 shows an elevation of the ironwork of the stove without the brick Fig. 291. Fig. 292. HORIZONTAL SECTION CROSS SECTION. casing which forms the air-circulating space. Fig. 291 is a liorizontal section of the stove and casing, and Fig. 292 is a cross section of the stove alone. Fig. 293 shows a sectional elevation at right angles to Fig. 292. At Fig. 294 the stove is shown in perspective inside the brick casing, a portion of which has been removed to show the stove in position, and the cold-air and hot- air liues. constantine's convoluted stove. 445 This stove is formed on the model of the well-known " gill " stove, but with the flsinges or " gills " made hollow, so that the flame and hot gases are in contact with the outermost surface of the projections. Like the gill stove, it is made in sections, which are bolted together to form any desired depth of body. The " convolutes " are " slightly arched or dome-shaped, each being deeply grooved to form a chamber, with ah aperture at the top of each arch leading to the smoke-box. These grooves extend also down the sides. Each convolute is a separate casting, and is in itself a moderate-sized stove, the inner and outer surface being equal. The convolutes are held together by bolts (shown in Figs. 290 and 291), and are connected by a peculiar her- metical joint invented by Mr. Constantine, and made tight by the use of iron borings." In order to diffuse the hot gases and flame into the grooves Fig. 293. Or convolutes, and to prevent the too rapid escape of the heat by the chim- ney, fire-brick slabs are placed in brackets across the fire-space, and form a roof to the combustion chamber, or baffle-plate to the flame. These slabs aie shown in the cross-section Fig. 292. They equalize the temperature in the stove, and project the flame and hot gases into the convolutes where they are wanted. Fire-brick is also used to protect the iron from the immediate aiction of the fire at the sides and back near the grate-bars. The proportion of heating- to grate-surface is large in these stoves, being about 100 to I, and affords security against overheating the stove. The results of heating by means of these stoves are very satisfactory. The Manchester Royal Exchange has an area of 1,500,000 cubic feet, and is kept 445 CONSTANTINE'S STOVE IN MANCHESTER EXCHANGE. at a uniform temperature of 50 to 56° F by the expenditure of 2^ cwts. of coke per twenty-four hours. From its great area (the ground covered being some S,4oo square yards), the warming of this Exchange was a problem which is said to have caused considerable anxiety, but the successful warming of the Free Trade Hall in Manche.ster by the convoluted stove led to its adoption in the Royal Exchange. Two large stoves fixed in the basement were found to answer the purpose effectually, and with less labour and fuel than are required for many small churches under other systems. Fio. 294. The arrangement is simple. Fresh air is drawn from the top of the building down a shaft of about 6 feet square, through a cold-air chamber at the bottom in which it is filtered, and is then passed through the warming chamberTo two flues which run the full length of the hall, w^th branch flues into the plinths of the columns, from which the warm air is delivered. The quantity and cost of coke consumed during a period of seven years are as follows : — CONST ANTIKE'S STOVE IN MANCHESTER PANTECHNICON. 447 Fig. 295. 448 HEATING OF MANCHESTEK PANTECHNICON. Year. Tons. £. '. d. > 874-75 . 28 10 10 1875.70 . . 214 81.3 1876-77 . . 22| 8 10 74 1877-78 I9l 7 8 14 1878-79 ■ • • 3ii n 14 44 1879-80 21 7 17 6 1880-81 . 20 . 164^ tone, 7 10 Total for 7 years costing ;^6i II 104 or an average cost of _;^8 16s. per annum for fuel. The Manchester Pantechnicon, of which Fig. 295 sliows a sectional eleva- tion and Fig. 296 a basement plan, with a floor area, devoted to storage FiQ. 296. STOVES FOR TURKISH BATHS. 449 purposes, of 90,000 square feet, is warmed at a cost of little- over ;^io per annum. The illustrations give an idea of the extent to which the heated air must be distributed in this case. At the Arlington Baths * in Glasgow, the hot air for the Turkish bath is supplied by these stoves. " The cubic capacity of the hot and hottest rooms is about 17,700 feet, giving a proportion of i square foot of cast-iron heat- ing-surface in the stoves to about 23.8 cubic feet of contained space." " The Fm. 297. heating and ventilation of these rooms (with the necessarv shampooing- I'oom) is obtained by a consumption of from 48 to 60 cwts. of ^as coke per week of fifty-five hours." The Turkish baths at Llandudno Hydropathic Establishment are also heated by these stoves at a fifth of the cost of the plan formerly employed there, the temperature of the hot rooms being maintained at 200° F. insteid of 150° F., as formerly was the case, and the ventilation being said to be excellent. Coke being the fuel generally employed in these stoves, no smoke is pro- duced in working them. • See J. L. Brace, On tlie Heating; and Ventilation of Turkish Baths, " Proc. Phil. Soo. Glasgow;" also J. Oonstautine, on "Practical Ventilation and Warming," p. 77 (London: Churchill). G G 4SO BISSETT'S hot-air stove. — HOT-BLAST STOVES. Another hot-air stove successfully introduced into Turkish baths is the multitubular heating stove invented by Mr. John Bissett, clubmaster at the Victoria Baths, Glasgow, and illustrated in Fig. 297. The furnace and com- bustion chamber, the latter separated from the grate by a bridge of fire- brick, are distinct from the chamber containing the vertical wrought-iron heating-tubes, so that the tubes do not come in contact with the fuel, or even with flame. The roof of the furnace is used as heating-surface, as well as the outside c.ising which encloses the tubes, whilst air is heated also by passing upwards inside the tubes. The flame is kept from striking on the tubes by a baffle-plate, which directs the hot products of combustion to the top of the chamber containing the tubes. From this point, the gases have to descend in contact with the outside of the tubes until' the flue leading to the chimney is reached. In the illustration Fig. 297, d is the fire-brick bridge between the grate and the combustion chamber. The flame and hot gases escape upwards, as shown by the arrow, to the top of the chamber containing the vertical tubes, and then descend in contact with the exterior surface of the tubes to the chimney flue and damper, f. a is the ash-pit. Cold air enters at b, and ascends the vertical tubes, entering them as the arrows indicate at c. Air is also heated in the space e above the fire-brick roof of the furnace, g showf the tubular chamber in sectional plan. The stove is put together with a view to f ak;ility in carr3rhig out "repairs when necessary, and it gives good results at the Turkish baths of the Victoria Baths Company. The hot room in these baths has a capacity of about 9,000 cubic feet, and is heated to 150° F. in little more than an hour. The stove used for this room is 5 feet by 2 feet 9 inches, with 100 tubes of 2 inches diameter. The hottest room is heated to 200° F. by a stove of fifty-five 2-inch tubes 4 feet high. These stoves are in operation from 90 to 100 hours per week, and in winter use in that time between them 20 cwts. of gas coke — ^in summer much le.ss. The temperatures are main- ' tained in the rooms very steadily^ and the ventilation of the rooms is excellent. The various modifications which have been adopted for raising air to a high temperature are very numerous, and it is impossible to give illustrations even of all that have been most generally employed. Herder's Erwarmung der Gehlaseluft, and P6clet Sur la ChaJsur, contain numerous details of the mode of applying the hot blast to lead and iron smelting. Hot-blast Stoves. — The application of hot air to iron smelting is of far greater importance than any use of heated air for warming or ventDating buildings. The introduction of hot blast caused a revolution in the practice of the smelting process, which resulted in an enormous increase in the manu- facture of iron, whilst the quantity of fuel used per ton of iron was very greatly reduced. Mushet* stated that in Scotland the amount of the saving in quantity of coal used in the blast furnace was not less than 100 per cent., but that the coals in that quarter do not on an average contain more than 50 per cent, of carbon. In South Wales the saving did not exceed 25 per cent., where the coals contain from 80 to 90 per cent, of carbon. So all over England it was found that the saving was intimately connected with the percentage of carbon in the coal. And this, remarks Mr. Mushet, is a rule which in the very nature of things ought to exist, for, after all, it is not the volume of coals alone which is the point for consideration, but the quantity of solid matter of fuel — viz., the carbon which is present in it. The results in quantity of pig-iron produced per furnace per week, and in quantity of fuel used per ton of iron produced, during three periods at the Clyde Ironworks, the blowing engine having been the same in all, were * "Papers 'in Ivon and Steel," 1840, p. 310. HOT-BLAST STOVES. 451 compared by Dr. Clark in a paper* quoted by Dr. Percy. The periods referred to are — the first six months of 1829, when cold blast was exclu- sively used with coke as fuel ; the first six months of the following year, when the blast was heated to 300° F., coke being still used ; and the first six months of 1833, when raw coal was used in the furnaces, the blast having been heated to 600° F. The following are the results : — Coke and Cold Blast. From Jan. 7 to Aug. ig, 1829. Coke and Hot Blast 300° F. From Jan. 6 to June 30, 1830. Coal and Hot Blast 600° P. From Jan. 9 to June 30, 1833. Average Weekly Make of Plar-iron in Three Furnaces. Average Con- sumption of Coal per Ton of Pig-iron. Average Weekly Make of Pig-iron in Three Furnaces. Average Con- sumption of Coal per Ton of Pig-iron. Average Weekly Make of Pig-iron in Four Furnaces. Average Con- sumption of Coal per Ton of Pig-iron. Tons cwts. qrs. no 14 2 Tons cwts. qr&. 8 I I Tons cwts. qrs. ' 162 2 2 ToQS cwts. qrs. 5 3 I Tons cwts. qrs. 245 'Jons cwts. qrs. 2 5 I It appears from these results, t Dr. Percy remarks, that by the applica- tion of hot blast the same amount of fuel reduced three times as much iron, and the same amount of blast did twice as much work as previously. Such extraordinary results could not fail to direct attention to the difference in the nature of the combustion produced under the two sets of conditions, so that we may say that the introduction of hot blast has led to considerable advance in the understanding of the theory and practice of combustion. Prior to the introduction of this invention it is evident:}: that very crude ideas prevailed both as regards the theory of smelting and as regards the part played by the air used in combustion. The difference between amount of heat and calorific intensity, or the temperature of combustion, was not recognized, nor did any one take into account the absorption of heat caused by the expansion of air on its being heated inside a furnace. The efficacy of the combustion in blast furnaces was supposed to depend on the absence of moisture in quantity in the blast, better combustion being obtained in the frost of winter, and this led ironmasters to cool the blast as much as possible, even employing methods which defeated their end as to freedom from moisture. For a long time after the subject became better understood, the pre- vailing opinion was that the results obtained with hot blast are due to the Mgher temperature and greater activity of combustion occasioned by its use. As heat is not abstracted in this case by the expansion of the air, nor by heating up the carbon and oxygen to the temperature of combustion, except through a small range, the full value of the temperature produced by the union of hot carbon and hot oxygen is realized — a higher temperature of combustion is available, and the chemical union which we call combustion proceeds more rapidly, so that there is also a larger amount of heat avail- able. The efiects of this high temperature in the zone of combustion extend to a considerable height in the furnace, causing the quicker reduction of the oxides of iron to the metallic state, and also the heating up of the solid materials previous to their entrance into the zone of intense combustion. There is much force in this view of the matter, which is still held by the advocates of very hot blast. Sir Isaac Lowthian Bell has, however, introduced some important con- siderations which cannot be ignored in dealing with the subject, the efiect * On the Application of the Hot Blast in the Manufacture of Cast Iron, by Dr. Clark Prof, of Chemisti-y at Aberdeen, "Proo. Roy. Soc. Edin.," March i5, 1831;. ' ' t See also Mushet, " Papers, on Iron and Steel," Appendix, pp. 909-923. X Mushet, op. cit, Preface, p. xvi. ; also pp. 321 et aeq. G G 2 452 THE INVENTION OF HOT BLAST. of which is to modify considerably all the generally accepted ideas as to the value of higher temperatures of blast, or even of hot blast at all, as com- pared with cold air. This we shall refer to farther on. Mr. Neilson, the inventor of the hot-blast system, has left on record* an account of the circumstances which led him to the idea. "Six or seven years," he said, " before he brought out the plan, he had read a paper before the Glasgow Philosophical Society on the best mode of taking out the mois- ture from the atmospheric air in summer time, previous to its entrance into the furnace through the tuyeres ; for it was found that the make of iron was much impaired in summer weather, both in quality and quantity, and he had become satisfied that the cause lay in the greater proportion of moisture contained in the air at that season. His first idea was to pass the air through two long tunnels containing calcined lime, so as to dry it thoroughly on its way to the blast cylinder of the blowing engine ; but this plan was not put to trial. About that time his advice was asked in regard to a blast furnace, situated at a distance of half a mile from the blowing engine, which did not obtain a sufficient supply of blast at that distance, and consequently did not make so much iron as two similar furnaces situated close by the same engine ; and it then occurred to him that since air increases in volume according to its temperature, if it were passed through a red-hot vessel before entering the distant furnace its volume would be increased and it might be enabled to do more duty in the distant furnace. Being at that time engaged in the Glasgow Gasworks, he made au experiment at once on the effect produced on the illuminating power of gas by a supply of heated air brought up by a tube close to the gas-burner, and found that by this means the combustion of the gas was rendered more perfect and intense, so- that the illuminating power of the particles of carbon in the gas wag greatly augmented. He then tried a similar experiment with a common smith's fire, by blowing the fire with heated air ; the effect was that the fire was rendered most brilliant, with an intense degree of heat, while another fire blown with cold air showed only the brightness ordinarily seen with a high heat. Having obtained such marked results in these small experiments, it then occurred to him that a similar increase in intensity of combustion and temperature produced would attend the application of the same plan on a large scale to the blast furnace ; but his great difficulty in further develop- ing the idea was that he was only a gas-maker, and could not persuade iron- masters to allow him to make the necessary experiments with blast furnaces at work. At that time there was great need of improvement in the working of blast furnaces, for many furnaces were at a stand for want of blast, being unable to maintain the necessary .heat for smelting the iron ; and, unless as- much as ;£'6 per ton could be obtained for the iron, no profit was realized,, on account of the heavy expenses attending the furnaces. A strong pre- judice was felt against any meddling with the furnace, and a kind of super- stitious dread of any change prevailed, from the great ignorance of furnace managers with respect to the real action going on in the furnace, and the causes of the fluctuations that occurred. When a furnace was making No. i iron, no one would be allowed to touch it, for fear that if any change took place it might be many weeks before the furnace got round again from white iron." He at length succeeded in getting an opportunity of trying the application of heated air for blowing a furnace at Clyde Ironworks, near Glasgow, and, though the temperature of the air was raised not more than about 50° F., he was glad to be able to make a trial even with so small an amount of heat. This- first imperfect trial, however, showed a marked difference in the scoria from the furnace, which was less black and contained less iron ; and he was therefore anxious to try the plan on a more extended * " Proc. Inst. Meoh. Eng.," 1859, p, 98. NEILSON'S FIEST APPARATUS. 453 scale, which, after some years of struggling with perseverance against the prejudices of ironmasters, he was at length enabled to do at Clyde Iron- works. The first apparatus for heating the blast which was used at Clyde Iron- works early in 1829* is illustrated by Figs. 298 and 299, the latter being a transverse section of the apparatus. " It consisted," according to Mr. Fia. 299. FlO. 21 Henry Marten's description, " of a small wrought-iron heating chamber, A, Figs. 298, 299, about 4 feet long, 3 feet high, and 2 feet wide, in con- struction similar to a waggon-head steam boiler, which was set in brickwork with a grate, b, below," as was also the arrangement in the old-fashioned steam boiler. " The cold blast entered at the end immediately over the grate, and passed out to the tuyere from the other end, being warmed in its passage along the chamber to a temperature of about 200° F. There was one of these heating chambers to each tuyere ; the total area of fire-grate per tuyere was about 4 square feet, and the area of heating surface of the chamber 35 square feet." This apparatus, though successful in heating the blast through a short range of temperature, proved not durable, as the boiler-plates forming the chambers a a quickly oxidized, or, in fact, were burned through, under the influence of the air and the red heat to which they were exposed. Mr. Neilson's experience with cast-iron retorts in the gasworks having shown him the greater durability of cast-iron when exposed to high tem- peratures, he soon substituted cast-iron retort- shaped heating vessels for the chambers a a. This arrangement is shown in Fig. 300, and " was found to be a great Fig. 300. improvement on the original plan, lasting longer and raising the temperature (if the blast to about 280° F. It was constructed at Clyde Ironworks about the end of 1829." These heating vessels were " cylindrical cast-iron tubes, A (Fig. 300), shaped like a bottleneck at each end for the admission and discharge of the blast. They were about 2 feet 9 inches diameter and 6 feet long. As in the former case, there was one of these vessels to each tuyere, but the heating surface was increased to 55 square feet per tuyere, or one * See Heni-y Marten, On Hot-blast Ovens, "Proc. Inst. Mech. Eng.," 1859, pp. 62-86. 454 EARLY FORMS OF HOT-BLAST STOVES. and a half times the surface exposed in the first application, and the grate area was increased to 1 1 square feet, or nearly three times." A further improvement consisted in wholly enclosing the heating vessel in the heating furnace, the roof of the chamber having been in the former case exposed to the atmosphere. In the arrangement carried out at Clyde Works in 1830, and shown in Figs. 301 and 302, there was a great advance made in the direction of increased Fig efficiency. The grate area was increased to 28 square feet per tuyere, five grates, B B, being employed for two tuyeres. The heating chamber "was formed of cast-iron pipes, a, of 18 inches diameter, completely enclosed in flues, and having a total length of about 100 feet, giving 240 square feet of heating-surface area per tuyere. The temperature of blast obtained by means of this arrangement was fully 600° F., lead having been melted by the heated air. So great an improvement was realized in both the quality of the produce and the yield of the furnace worked under these new con- ditions that furnace managers were encouraged to overcome difficulties in working and defects in arrangement which continued to manifest themselves. The elevation of the temperature caused severe strains to be thrown upon the metal of the stoves wherever inequality of heating was produced, because irregular expansion and contraction and durability were not as yet provided for in the form given to the stove. EARLY FORMS OF HOT-BLAST STOVES. 455 The first hot-blast stove or oven properly so called, constructed of cast- iron bent or arched pipes, was erected by Neilson, at Clyde Ironworks, in 1 832, and is shown in Figs. 303 and 304. " In this case the irregular fire-grates, five to two tuyeres, were done away with, and an oven with one grate only Fig. 303. was constructed behind each of the tuyeres, now three in number, a tu3'ere, A, being at this time inserted at the back of the furnace in addition to the two, one on each side, which were used before the introduction of hot blast. In the oven now constructed the blast, instead of being carried, as formerly, Fio. 304. dong one continuous heating-tube directly over the grate, was admitted into a main pipe, c, running longitudinally at one side of the grate b. On the top of this main pipe a number of deep circular sockets were cast, with apertures into the pipe, and on the opposite side of the grate a simOar main 4S6 EAELY TRIALS WITH HOT BLAST IN STAFFOEDSHIRE. pipe, D, was fixed, with corresponding sockets and apertures, which was connected with the tuyere-pipe inserted into the furnace. The two longi- tudinal main pipes, c and D, on each side of the grate were then connected by cast-iron tubes, e, each forming a semicircular arch of 6-feet span, fastened into the sockets with well-rammed iron cement. The cold blast was supplied to each of the ovens by a branch pipe taken direct off the large main from the blast engine, and entered the oven at the end farthest from the grate. It then passed through the arched tubes e, over the fire, into the pipe d, on the other side of the grate, and thence to the tuyere, leaving the oven at the end next the grate. " The whole of the apparatus was enclosed in an arched brick oven, so as to retain and reverberate as much heat as possible. " The general dimensions of the apparatus for each tuyere were as follows : — " Diameter of longitudinal mains at each side of grate . 1 2 ins. Length of „ „ „ „ .10 ft. Distance between longitudinal mains, centre to centre . 6 „ Number of arched connecting tubes ... 9 Internal diameter of „ „ 4 ins. External „ „ _ „ . . • 7 » Height from grate to under-side of arched tubes . 4 ft. 4 „ Area of heating-surface per tuyere . . . . 150 sq. ft. ,, fire-grate per tuyere . . . . 15 „ " On comparing this with the previous plan shown in Figs. 301 and 302, it will be observed that this apparatus, owing to its improved construction, maintained as efficient a temperature with less than two-thirds of the heating surface per tuyere and a little more than half the grate area." Further experience of this apparatus showed that improvement was still required, and, for a considerable number of years subsequent to the inlrj- duction of this oven of Neilson's, new forms were tried both by Mr. Neilson and by his licensees in various parts of the country. "In 1834, Messrs. Lloyds, Fosters, & Co., of Wednesbury, erected an apparatus at their works for heating the blast, and singularly enough, at that early period, proposed to apply the waste gases from the tunnel-head for this purpose." This apparatus " consisted of a circular wrought-iron heating chamber placed within the brickwork of the tunnel-head, the flame from the furnace rising up through the centre of the chamber. The blast was supplied into it from the cold main through several small apertures, which distributed the air against the plates of the chamber on the side exposed to the action of the flame, and the hot blast was conveyed in a pipe down to the tuyeres. This apparatus was very expensive in its first construction, and constantly re- quired repairs. It produced a heat of only about 360° F., so that a small supplementary oven was required near the tuyere to raise the temperature of the blast still further previous to its entrance into the furnace." Con- sequently this plan was soon abandoned. In order to remedy the burning of the arched pipes of the oven illus- trated in Figs. 303 and 304, ovens were constructed at Calder Ironworks and by Mr. Firmstone at Lay's Ironworks, near Dudley, on an improved plan. The arched tubes were elongated into the form of siphon pipes, and in some instances carried to a height of 10 feet above the main. As an additional safeguard, at Lay's Ironworks the grate was placed in a separate compart- ment, and the hot gases were passed into the oven through small narrow apertures between t'le horizontal mains. At this stage, the plan of having a separate oven for each tuyere was abandoned, and the general heating capacity was so much increased that BOX-FOOT OVENS FOE HOT BLAST. 457 one oven of the following dimensions was found to be capable of heating the blast for three tuyeres to a temperature of 600° F. : — Length of longitudinal mains . . . . 7 ft. 6 ins. Number of siphon pipes . . . . ■ • 9 Area of direct heating surface, total . . . . 240 sq. ft. „ „ „ per tuyere . 80 „ Area of fire-grate, total ... . 9 » „ „ per tuyere 3 „ Several continuous-pipe ovens were designed about 1836 and tried for a time. One of these had horizontal pipes in two tiers with sharp round bends forming a zigzag path for the air. This was erected in 1836 at Dowlais Ironworks, in South Wales, and had a heating surface of 9 square feet giving a blast temperature of 300° F. A spiral-pipe oven was erected at Ebbw Vale Ironworks, and was heated by the waste gases from the furnace. It worked well, maintained a good heat, and was seldom out of re- „ pair, but it involved the inherent defect of all continuous-pipe ovens, which was the great loss of pressure of blast by friction in consequence of the whole of the blast having to pass at a rapid rate through a single pipe. The box-foot oven erected in North Staffordshire and at Ystalyfera, at the latter being fired by the waste fur- nace gases, is shown in Figs. 305 and 306. This was another good form of the continuous pipe oven, against which the greatest objection was the loss of pressure of blast through fric- tion. It consisted of "a series of separate cast-iron foot-boxes placed in the position of the longitudinal main on each side of the grate. Each box was provided with two sockets cast Fig. 306. on the upper side, excepting the two boxes at each end of the oven, which' had only one socket, the other end of these boxes communicating with the inlet or outlet pipe. Cast-iron siphon pipes were erected in the oven, each pipe footing in adjoining boxes, and the blast, entering the oven at one end, had to pass up and down alternately through the whole series of siphon pipes before leaving the oven at the other end." Fio. 307. Figs. 307 and 308 show a horizontal-pipe oven erected at the Monkland Works, near Airdrie. It consisted of two main vertical pipes, e e, of horse-shoe pattern, with nu- merous sockets, cast on one face, standing opposite to each other 6 feet apart. Fifteen small straight cast-iron tubes, F, joined these two mains, being inserted in the sockets and tightly jointed there. This design is interesting as being the first example of a curved main, but was not otherwise notable. 458 SIPHON-PIPE AND CONCENTKIC-PIPE STOVES. Fia. 309. A modification of the siphon-pipe stove is shown at Fig. 309, and con- sisted of two horizontal pipes, a b, to the upper surface of which a series of fl -pipes, c, were fixed, as shown in the drawing at d, the joints being encased in brickwork. These pipes were heated by a powerful fire, e, the flame from which played round the upright pipes, and passed off at/ through a flue built on the top of the stove. The walls g acquired a red heat, and assisted in maintaining a uniform temperature. The blast in being forced through the ap- paratus met with a stop-plate in the horizontal pipe a, which it entered first ; the air ascended the ri-pipes corresponding with this section, and passed on through the opposite pipe, b, until it en- countered another stop - plate, when it re-entered another series of n -pipes, and thus continued ascending and descending until it had acquired the necessary tem- perature. This plan of heating the air was not economical; the air- current travelled in a direction contrary to that of the smoke, through only the half of the circuit in the pipes, and the hot gases escaped from the furnace at a very high temperature. At Codnor Park Ironworks a more advantageous plan of heat- ing the blast was introduced. Two very wide cast-iron pipes, B and D, Figs. 310 and 311, were set in a furnace in such a manner that the flames should play first over the entire length of the one, and then in the opposite direction over the other, before esca- ping to the chimney ; into each of these, pipes of less diameter, shown at A and C, were inserted, open at both ends, one end projecting beyond the brickwork of the fur- nace. The air from the blowing cylinders was admitted into the upper narrow pipe, and, passing to the far end, returned through the annular space between it and the outer pipe; thence it was conducted by a short cross pipe to the annular space between the other lower pipes, aid ■■ 1 H^^\ - 1^1 A« V-^ M^l ^^^^^^^^H ■ ^^^^^^^Ir^ ^- If 71 ■ 11 1 ^^^H ^^^^^^^^■Ur ' If /■ II ^ ^^1 ^^^^r'' r M HI 1 ^B r ii m ' H 1 ll Hi ^1 ■^£?1 ■■(al ^1 1 1 ■B| ^1 ^^^^^1 ^^^^^ H ^^^sX^^ ^^5^ ^j Fig. Fig. 311. INCRKASED SIZE OF HOT-BLAST STOVES. 459 passed to the tuyeres through the second pipe of small diameter. The air thus traversed in the contrary direction to the smoke, and the inner iron pipes were of great value in increasing the heating surface. The improvement in the manufacture of pig-iron which followed the introduction of the hot blast causing an increase in the quantity made, furnaces were consequently enlarged and larger quantities of blast were required. Ovens of larger capacity were thus rendered necessary, and the introduction of these, in some cases, brought new conditions and new difficulties. At first double ovens were tried, two ovens of ordinary size being placed either end to end, or side by side, the latter being considered the better from a mechanical point of view, although the former was more frequently adopted on account of other considerations. Fig. 312 shows the "end on" plan applied to the construction of a triple Fig. 312. I . I ^8^^®©)^ 7 d Fio. 313. oven, which was a form of long oven ordinarily in use in Staffordshire in early days, from about 1837, when it was first erected. This oven consisted of twenty-five pipes of circular section having 1,200 square feet of heating surface and 126 square feet of grate area, and was capable of maintaining blast for six tuyeres at 600° F. In working with large ovens, it soon became necessai-y to introduce stop valves at each end of the oven for the purpose of isolating any oven for repair or examination, and also for testing the amount of leakage of blast in each oven. Means had also to be provided for checking the sudden increase of heat in the ovens consequent on the stoppage of the blowing engine at casting time. Even with long siphon pipes the difficulties of expansion caused some trouble, and various sec- tions and arrangements of pipes were tried.* Fig. 313 shows the form which ultimately was in many cases adopted, and which gave very good results. Fixed main socket-pipes of square sec- tion were used, although loose mains had been found to answer admirably ; the siphon pipes were of flat oval section, with vertical legs parallel for some distance above the grate or combustion space, instead of inclining towards each other, and con- nected at the top by a large semicircular arch. This form of siphon pipe stood well, and was 1^ neither liable to be burnt near the sockets nor apt to crack at the arch, the strains being distributed over a considerable length. • See Henry Marten, On Hot-blast Ovens, " I'roe. Inst. M.E.," vol, for 1859. pp. 73-79. 46o PISTOL-PIPE AND CIRCULAE STOVES. The "pistol-pipe" stove is illustrated in Fig. 314, where it is shown as adapted for the use of waste furnace gases in its combustion chamber h ; and another modification of the rectangular stove used in Lancashire and other parts will be found illustrated in works on metallurgy.* American practice Fia. 314. Pig. 316. % %—M~ Fig. 317. will be found illustrated in "American Iron and Steel Works," by A. L. Holley and Lennox Smith. F. Kohn's " Iron and Steel Manufacture ".also contains useful informa- tion on this subject. Hound ovens were first introduced by Mr. Martin Baldwin at Bilston in • See Greenwood's " Metallurgy," vol. i. figs. 26, 27, 28. See also " Engineering," Nov. 22, 1878, p. 410. ° BALDWIN S ROUND OVENS. 461 1 85 1, the first round oven being shown in Fig. 315. The object of this construction was to insure the possession of a main of such a form that its expansion or contraction should not tend to disturb the sockets of the upright pipes, while these upright pipes should have in their form provision against fracture or burning, and also against any expansion which might strain the socket joints. Another important object in designing this oven wsls to provide a form of casing which combined a good fire-grate area with compactness, the minimum amount of surface for radiation, and the greatest amount of reverberation or reflection of the radiant heat to the pipes. In durability and freedom from fracture of pipes and joints, the round oven was most Fig. 318. successful, the pipes and joints standing the stress of work without repair for several years. When the improvements in internal arrangement shown in Figs. 316 and 317 were added, the heating capacity of the oven was increased by one-third and the consumption of fuel was smaller. The advantages of the core consisted in increasing the reverberatory surface and in providing a reservoir of heat which corrected any irregularity in the temperature of firing. The vacant space in the centre of the tubes was thus profitably filled, and the hot gases were forced into more intimate contact with the pipes. The alterations in the flues at the top and in the division of the fire-grates below were also beneficial, so that, with a fire- 462 BALDWINS OVAL OVENS. grate area of 38 square feet, and an area of direct heating surface in the pipes of 850 square feet, or 280 square feet per tuyere for three tuyeres, this oven was capable of heating the blast for three tuyeres to a temperature of 800° F. A later improvement in this direction is shown in Figs. 318-320, Fia. 319. the object of arranging the mains in the horse-shoe form, as shown in the sectional plan, Fig. 319, having been primarily to obtain more heating sur- FiG. 320. face than one round oven afforded without the expense of erecting two of them. Fig. 320 shows a plan of the top flues of this oven. Some ovens erected on this plan, having 54 square feet of fire-grate area and 1,500 square feet of direct heating surface in the pipes, were said to be capable of supplying blast heated to 800° F. for ten tuyeres. This arrange- ment also provided means for cleaning the flues both above at d d and below riRE-BEICK EEGENERATIVE STOVES, COWPEE'S STOVE. 463 at F r, and the spaces between the pipes by doors at e e, without interfering with the working of the ovens. With the introduction of improved forms it became possible to reduce the thickness of cast iron used in the heating pipes from 2^ inches in some early ovens to i inch, thus not only saving metal in construction, but in- creasing also their etficiency in transmitting heat to the blast, the rate of ti'ansmission being inversely as the thickness of the metal. The use of a simple pyrometer, such as Gauntlett's, which was frequently used, enabled a constant heating effect to be produced without waste of fuel, and, as the result, considerable saving in fuel was realized in those ovens fired with solid fuel. In early examples, 8 or 10 cwts. of slack coal per ton of iron made were required to heat the blast to 320° F., whilst later practice with improved ovens shows blast heated to 800° F. with 4^ to 5 cwts. of slack per ton of iron. There has thus been considerable advance made on the primitive arrangements introduced by Neilson for heating the bla,st in ironworks. Some cast-iron pipe stoves heated by coal fires have been worked to a recent date in connection with open-topped blast furnaces,* but the plan of closing the tops of blast furnaces and using the waste gas as fuel having become almost universal, of course modifications in the arrangement of iron pipe stoves became necessary to suit the altered mode of firing. Moreover, higher temperatures of blast have come to be more in demand as the impression has prevailed that economy of working is to be obtained in this direction, and in result the temperatures originally introduced by Neilson have been left far behind — although Neilson has left on record t his belief in the value of higher temperatures than he was able to obtain. There are iron pipe blast stoves in use, such as those of Mr. Gjers and others, which are fired by gas J and used to heat the blast to temperatures of 1,000° to 1,200° F., some ironmasters holdingthat they are quite equal to that work, and that further economy is not reached by employing higher tempera- tures. There are, however, others who maintain that there is no limit to the economy attainable by the use of higher blast temperatures, except that which is fixed by the combustion temperature of the waste gases, and, we may add, that of the durability of the material of which the stove is constructed. Cowper's Stove. — With temperatures of 1,000° to 1,200° F. the limit of safety with cast-iron pipe stoves seems^to have been reached, but stoves constructed of fire-brick have been introduced, and these greatly extend the range of temperatures at command. An unsuccessful attempt was made in this direction by Siemens,§ but to Mr. E. A. Oowper belongs the honour of first introducing this impor- tant improvement in blast stoves. Mr. Cowper, who described his original design in a paper read before the Institution of Mechanical Engineers in i86o,|| and communicated his later improvements to the Iron and Steel Institute,1[ adopted the principle of the so-called "regene- rators" of the Siemens furnace, placing them inside air-tight wrought-iron casings lined with fire-brick. This construction of the " Cowper stove " intro- duced a new era in blast-furnace practice, rendering it possible to heat the blast to about double the temperature that was usual at that time. The stove is first heated up for about three hours by the combustion of gas within it, and then, the gas being turned off, cold blast is introduced, which, * Percy's " Metallm-gy," vol. Iron and Steel, pp. 399-418 ; " Popular Encyclopsedia," art. Iron. f " Proc. Inst. Mech. Eng.," vol'. 1859. p. 68 : vol. i860, pp. 64, 66, 67. J See " Engineering," Nov. 22, 1878, p. 410, &o. § See Dr. Percy, " Metallurgy," vol. Iron and Steel, p. 428. II "Proceedings," vol. i860, pp. 54-73, plates 8-14. ^ "Journal," vol. ii. 1883, p. 576. 464 cowpee's stove. Fia. 321. SEC TIOWAt ! ELBVATie w MfMfeemt c J/L. COWPEE'S STOVE— ACTION OF EEQENERATOE. 465 passing through the regenerator, takes up heat from the very surfaces that had previously absorbed it. The stoves are worked in pairs, so that as one is heating the blast, the other is being heated up. The heating of the regenerator is effected by admitting blast-furnace gas through a valve at the bottom of a large flame flue, and air to mix with the gas by another valve. The gas being ignited, a large flame is formed, which passes up the flue and then descends once through the regenerator, composed of bricks in the form of a honeycomb, thus heating it most at the top. So perfect is the absorption of heat that the products of combustion, as they pass away through several openings to the chimney valve and thence to the chimney, are at a very low temperature ; in fact, only about high enough to keep up the draught. When the heat has penetrated down- wards nearly to the bottom of the regenerator after it has been in action for several hours, the valves just named are closed and the cold- and hot-blast valves are opened so that the blast may pass in at the bottom of the regene- rator and, after traversing it upwards, pass from the top down the flame flue to the hot-blast valve. It must not be understood that the whole mass of brickwork or " filling " inside the iron casing is heated up or cooled down to the same point. Were this done in heating up, the products of combustion or hot gases used for heating would pass away at the chimney flue end at the temperature to which the brick surfaces had been raised, and thus much heat would be lost. The upper portion of the filling is always hot and the lower part always cool, and " as the hot end approaches the temperature of the fire whilst the cold end is at the temperature of the chimney. flue, so the temperature of either end varies but little even after several hours' heating ; the heat, however, works farther in at the hot end, and there is less length of cold part at the cold end. The regular scale or gradation of temperature of the great bulk of the regenerator is simply shifted lower down in the mass of brick- work, there being a greater length of hot part then left at the upper end." When the blast is admitted, " precisely the opposite result takes place, in the gradual shifting upwards of the scale of temperature in the regenerator, until, by long-continued action of the cold blast in taking up heat from each course of bricks in succession, ttere is only a short length of thoroughly heated part left at the top, and a greater length of cooled part left at the bottom of the regenerator when it is time to change again." The action of this apparatus thus seems to come as near to perfection as is possible with mechanical appliances, the hot gases being cooled to from 150° to 250° F. before they escape to the chimney, whilst the blast is heated up to nearly 1,500° F. ^^°- 3^2. The Cowper stoves have been improved since their first introduction in i860, but the last im- provements — viz., the honeycomb bricks, and the branched psissages to chimney valve — now used by Mr. Cowper are said to have surpassed any- thing that has hitherto been done. In Fig. 321, I is the iron casing of the stove, B is the brick lining ; R is the regenerator, a por- tion of the honeycomb filling — Fig. 322 — being omitted in the plan in order to .show the grids, o, and girders, p, on which they rest ; h is the hot- r blast valve, c is the cold-blast valve, a is the air . I valve, G is the gas valve, v is the chimney valve, | F is the flame flue, N is the gas-burner, m are man-holes for access to the bottom of the stoves for taking out dust brought down by the firing of a gun or by the action of a brush thrust up from ■466 WHITWELL'S STOVE. below, and t is tke throttle valve for suddenly discharging the air from the stove and blowing out dust. The bricks forming the regenerator filling of "honeycomb" form are shown in Figs. 322, 323. The short spurs on the angles of each brick cause it to form other passages besides its own central one, and they impart stiffness Fia. 323. Fig. 324. and strength to the brick. In consequence of the strength of this form, the bricks can be made only 2 inches thick, which, of courge, permits of more even heating up than would be possible with thick masses, and is of advan- tage in other ways. The hexagonal form also has the advantage of prevent- ing hanging of the dust. It is found that dust does to some extent hang in paissages having square corners. About four hundred Cowper stoves have been erected and put to work in varions parts of the world, and they are said to make 15 to 20 per cent, more iron from the same plant than could be produced with cast-iron pipe stoves. As a consequence, that proportion of fuel per ton of iron made is saved, and this is a strong incentive to the adop- tion of such appliances, ironmasters of late years having found it necessary to adopt the most economical methods of producing iron, on account of the verjj low prices prevailing. Whitwell's Stove.— The late Mr. Thomas Whitwell introduced a fire- brick stove, subsequent to Mr. Oowper's invention, which was worked under licence from Mr. Cowper during the cvirrency of his first patent. The Whitwell stove has, however, been modified in form, and the principal differences between it in its present form and the Cowper stove con^st in the arrangement of the fire-bricks forming the heating surfaces, and in the manner in which the combustion of the furnace gases is effected within the stove. In the Whitwell arrangement the heating surfaces consist of a num- ber of narrow vertical flat walls or flues, shown at m in Figs. 324 and 325. In the Cowper stove the combustion of the furnace gases is effected in one ACTION OF COMBUSTION IN WHITWELL'S STOVE. 467 large flame flue or combustion chamber, whilst in Whitwell's arrangement the air required for the combustion of the gases is admitted at several points, and the combustion is thus completed only after the gases have partially traversed the stove. The Whitwell stoves are from 60 to 70 feet in height, and from 20 to 2 2 feet in diameter. They consist of a vertical cylindrical casing of wrought- iron plates rivetted together, within which is built a lining of fire-bricks, but between this lining and the outer shell is left a space of about i inch, which is filled up with granulated slag. Within the cylindrical chamber are built a series of narrow vertical chambers, m m (see Figs. 324 and 325), the different rows of which communi- cate with each other either at the top or at the bottom. Attached to the outside of the casing are cast-iron valves for regulating respectively the supply of gas, air, and blast to the stove, and for -p. ,, connecting the stove with the chimney. The casing, &c., of the valves for admitting the blast-furnace gases to the stove and connect- ing the stove with the hot-blast main are usually made hollow, and are cooled by the circulation of water through them.. Near to the bottom of the stoves are eye pieces, P P, arranged round the circumference, and through these a view of the interior is obtained so as to judge"of its tempera- ture and requirements. In the roof of the stove are apertures,' f f, closed by covers during the regular working, but movable for the introduction of long scrapers for cleaning the dust, &c., from the several flues ; also at e e, near the bottom, are arranged six openings for cleaning out the dust, &c., collected from the flues into the bottom of the stove, and which openings are closed by movable doors as required. The gases from the blast furnaces enter the stove by the valve a, whilst, at the same time, air enters through the air-courses, G, sufficient in quantity, however, only for the partial combustion of the gases. The heated gases then ascend through the vertical combustion chambers to the top of the stove (as shown by the course of the arrows), where the gases distribute themselves over the tops of the flues and descend by one or morfe chambers towards the bottom of the stove. Here more air is admitted, and the com- bustion of the gases is completed as they re-ascend in the stove through another wide combustion chamber. The products of combustion finally descend through the other narrow flues or chambers to the chimney valve, from which they escape to the atmosphere at a temperature of from 300° to 400° F. (149° to 204° C.) When the fire-brick chambers of the stove have been thus sufficiently heated, the gas valve. A, the chimney valve, c, and also the air valve, are each closed, whilst the cold-blast valve, D, and the hot-blast valve, B, which were previously closed, are thereupon opened. The current of blast thus enters the stove at its coldest point, d, near the chimney valve, and passes through the several passages towards the hotter parts of the stove, exactly in the reverse direction to that pursued by the gases in heating up the stove. In this manner the blast, by passing over the heated fire-brick, becomes heated before it passes out at b, to the hot-blast main to a temperature of 1,300° or 1,400° F. (704° to 738° C), whilst higher temperatures are attained according as the reversal of the valves required for heating up the stoves and for passing the blast through the same is efiected at intervals more or less frequent. This arrangement of a second combustion chamber suggests the idea that the carbonic acid produced by the combustion in the first instance, 468 ADVANTAGES OF MASSICKS AND CROOKE'S STOVE. might prevent thorough combustion in the second chamber, and, as the primary combustion is purposely partial, the full heat of combustion of the furnace gas would not be obtained. Mr. William Whitwell, however, states that such a difficulty has not been experienced in working. " The second combustion chamber," he says, "enables us to burn off what unconsumed carbonic oxide remains in the gas, while the products of the first combustion chamber give their heat to the walls also, and in no degree interfere with the combustion. We have 800 to 900 stoves in all parts of the world, and the most successful practice, both in America and in England, is with Whitwell stoves." Massicks and Crooke's Stove.* — Massicks and Crooke have designed the stove shown in Fig. 326. It consists of a cyUndrical wrought-iron casing, with a conical top, which has a circular man-hole in the apex. This form of top obviates the difficulty and expense of having girders and cleaning doors. The internal brickwork arrangement is a series of segmental passages, commencing at the centre of the stove, where it is hottest, and terminating at the periphery, where it is coldest, thereby preventing radiation and consequent loss of heat, and affording, greater protection to the, iron casing. The gases to heat the stove, and the blast to be heated by the stove, are alternately passed through the segmental passages in opposite directions, and by this arrangement the largest amount of efficient and durable heating surface is obtained. The difficulty of economical and thorough cleaning of fire-brick stoves has always been, apart from cost, a most serious defect, and it is claimed for this, invention that by means of it this difficulty is overcome. Cleaning doora at the top and removal of brickwork are dispensed with by an arrangement of iron pipes, 2 inches in diameter, which are built into the brickwork of the- top of the stove directly over each segmental passage. Through these pipes a chain or rod is passed to the bottom of the stove, and through the cleaning door or doors a scraper is attached thereto, which fits exactly each segmental passage. This scraper is caused to ascend and descend by a simple working- rotary crane on the top of the stove, and in this way all the gas-dust adhering to the internal brickwork of the stove is entirely removed in a short time. The gas and hot-blast valves have water or air passing through them. The chimney valve does not require cooling, as the temperature of the escaping gases is reduced to about 300° F., and a simple form of mushroom valve is designed for this purpose. The advantages which are claimed for this stove are — comparatively small cost and simplicity of construction ; an effectual, rapid, and cheap mode of cleaning ; great structural strength, combined with a large amount of permanent heating surface. The main feature in this stove is the central heat. The passages are so arranged that as the hot gases approach the outer casing they become cooled down, until finally they are passed from the outermost passage under the centre of the stove to the chimney valve. The object of passing them towards the outside and then under the stove is to preserve both the iron casing and the bottom of the stove from too intense a heat. At each change from gas to blast the cold air first enters under the bottom of the stove, thence into the outermost passages, and thence inwards, gradually increasing in temperature by coming in contact with the hot brickwork, until finally it arrives in the central chamber, where it receives its final heat, and is thence passed direct into the tuyeres. This arrangement enables a light iron casing to be used, protected by only one course of brickwork. Five years' experience has tested the value of this design, and during that time it is said that not a single plate has been in- * "Jour. Iron aud Steel Inst,." vol. ii. 1882, p. 602. MASSICKS AND CROOKE'S STOVE. 469 jured by over-heating, although the central portion of the stove has been maintained at a red heat, never having been allowed to cool down except once in three or four months for cleaning purposes. The diagram Fig. 327 (p. 470) gives a graphic representation of the con- sumption of coke per ton of iron made with blast heated to various degrees of temperature. The diagram was prepared by Messrs. Massicks and Crooke from data obtained in practical work with furnaces working at the Fio. 326. A CAS VALVE Jl HOT BLAST VALV e CHIMNEY VALVE J> COLD BLAST VALVE E AJRVALVESFOK COMBUSTION OF b&S r CLEANING DOORS e a PLUG HDLE CASTINGS H HOT BUST MAIN 1 COLD BLAST MAIN Askam and Monzell Iron Co.'s works, and also at the Cumberland Iron Mining and Smelting Co.'s works. Messrs. Massicks and Crooke remark that, after long experience, it has been found that 1,300° F. is the most economical temperature for work with modern blast-furnace plant, producing 100 to 120 tons of high free carbon pig-iron (Nos. i, 2, and 3 Bessemer) per day of twenty-four hours. A higher temperature cannot be maintained so regularly at a uniform 470 PEINCIPLES OF HOT BLAST. point, and in the working of a blast furnace this is of very great im- portance. When it is considered that, in order to produce this yield of iron from one furnace, about 700 tons of air has to be passed through each pair of stoves in twenty-four hours, and raised from 60° to 1,300° F., some idea may be formed of the magnitude of the work. The result, however, makes it possible for the ironmaster to live, where a few years ago this would have been impossible with present prices of pig-iron. One or two other modifications of the fire-brick stove have been intro- duced subsequent to those mentioned, such as Ford's, Harvey's, and some in America and Germany, but they need not be described in detail. The table on p. 471, which was drawn up by Herr Lurmann,* gives some interesting comparative information regarding several of the best hot- Fio. 327. SJJcwt- _ 1 %hcuk ■', l%cJ: \ \ \ * .2ia^ ' A ^ -? •^OaJr % 5 3 5 iqcJ- \ <* 'I'foul' 's^ "\ l.^cJ' "4~ .^ • G c «« to 3 blast stoves in use. The data have been, where necessary, modified on the assumption that the blast which had to be heated was that required for one blast furnace of a daily consumption of 120 tons of coke, equivalent to 450 cubic metres of blast per minute.t Principles of Hot Blast. — The scientific principles which govern the use of hot blast have been demonstrated by Sir I. Lowthian Bell, who has reduced to accurate figures the relative efliciency of the heat of a unit of carbon when burnt outside the furnace (the heat being conveyed into the hearth by the blast) and of a unit burnt in the interior of the furnace. In Neilson's day, circumstances, especially in Scotland, made it appear as if the former was many times more efficacious than the latter, but better under- standing of the actions taking place in the blast furnace has supplied the * Stahl und Eisen, 1883, p. 27. t fiefer to " Jour. Iron and Steel Inst.," vol. ii. 18 the Surface required in Hot-blast Stoves." 3, p. 699, for an article " On Computing HEATING SURFACE AND COST OF HOT-BLAST STOVES. 471 of iting rface It per ibic tre of ast. ? Tj- tn 00 r^ 1^ U-) '^ in N 10 ■* t^ vo W iri 00 li-l M ^ vn N ro i-< ^ M 00 .5 '''aw 3 4 PO ^O N N od S 3 s 1 « ^^ 8 06 8 00 8 d d 8. 1 10 t^. M HH .£ ii g 8 g g g g 8 8 8 00^ 10 t< ^ § 0" U-l ? pf N a> 3 10 y3 00 N m r^ 00 t- ftSt, N M M ■§•• 8 ~Q T T "7 8 T 8 S ,=! Q 10 Ed H ■kSS M \o M 00 u-l (^ Tt- \o ^»j 10 ^ M tn ■^ •* N r^ M I-) 8 f^ lO vo m - 00 m ^ VO r^ CD ^O VO ■^ 10 ^ S.3-SS2S \6 10 d bH KH C^ cK q M N Oga-< M M w M t« 1 8 06 8 8 10 - 00 ly-l- ii s ^ t-t rn (^ hH "-I M 1 _|i-2li 8 8 g 8 8 8 N § W 00 00 i>- ■■^ 00 00 vo ^ ro ro N VO C^ i l^^l-S cT rf ■* -^ cS cS ■ feS 3 rr> m \o VO ■* ■* 10 lAj s |£ &. ■^ I-:- ■sii i g 8 g 8 8 i i 8 \o' fo m VO °aS o^ CX3 ■^ ^ 00 00 ■"d; •^ vO « N ■^ ■^ "^ '" ■^ ■asn m r'l M M « W fO (^ M u^ vO ' 98AO}SJO-Ofl ■uoijonpojj 9U0X 061 JO aoBiun J in u-i q vn u-i "-> q ■jsRia 3ao -loj p9jmb ■^ ■^ « N rh trh ro ro N uS vd -aj S3A0JS io 'oji t^ (3 , -O c c >-i rt (S C c* 'hb 1= C5 T3 H ;: (D .3 H iS (3 rf § 8 "s "m n >» , 1 ^ C 1 ^ ^ 1 -§■ c 1 C5 c d 1 6 d ■-c i 5S a 1 d C ^ (D ^ d sf' " Q Q d ■qq fi > « ^ 6 g w " N ro 4 vn ^* t>. 06 cK d « 472 PEINCIPLES OF HOT BLAST. explanation of the seeming anomaly ; for this, we are indebted to none so much as to Sir I. Lowthian Bell. He has shown that the keys to this sub- ject are the capacity of the furnace and the susceptibility of the ore which it contains to reduction by carbonic oxide, or, as otherwise expressed, the equalization of the rates of reduction and of fusion, whilst the index to the chemical changes taking place in the blast furnace is found in the relative proportions of carbonic oxide and carbonic acid which the escaping gases contain. The effect of increased capacity of furnace on the combustion within will be understood if we consider the nature of the action which takes place. " If a piece of carbon, such as charcoal," remarks Sir Lowthian Bell,* " is heated to redness, and continues to bui'n, surrounded on all sides by air, it will do so without any visible flame. Each molecule of the combustible is converted at once into carbonic acid with the development of the largest amount of heat its combustion can give rise to — viz., about 8,000 centigrade units of heat per unit of carbon. " If, on the other hand, several pieces of carbon are placed in contact with each other, and the air required for their combustion is made to pass upwards through the mass, a blue flame will appear at the top. This is due to the formation of carbonic oxide from some or all of the carbonic acid on" its passage through the heated carbon, this carbonic oxide burning in contact with the air. " In all low fires, such as the Catalan hearth and the refinery, the real nature of the combustion varies with circumstances, such as the depth of the fire and the temperature of the fuel, whether it be charcoal or coke. As a rule, we may take it that near the tuyeres of these shallow furnaces there is a certain amount of carbonic acid present, only part of which is reduced higher up to the state of carbonic oxide. In this way a portion of the carbon arrives at the surface of the fire in the form of carbonic 'acid, and there it mingles with that resulting from the combustion of any cacbonic oxide which may reach this point as such. " It thus happens that, in such arrangements, as those last mentioned, the whole of the carbon, in the one way or the other, passes up the chimney as carbonic acid, having evolved by its oxidation the greatest amount of heat it is capable of affording. It is clear, however, that, when the object of such a tire as the Catalan or the refinery is the imparting of heat to some body immersed in the fuel, it cannot be otherwise than an exceedingly wasteful operation. That portion of the carbon which is burnt below the surface of the fuel passes too rapidly upwards to have time to impart more than a mere fraction of its heat to the matter exposed to its influence. On the other hand, such combustion as takes place on the surface of the mass is scarcely in contact with the body to be heated, and exercises little or no useful effect. " Let us now compare the nature of the combustion as it is eifected in the blast furnace, and the application of the resulting heat, with that .just described. For this purpose we will suppose that the fuel is burnt in a furnace having a height of 80 feet. The result of several analyses t satisfied me that almost all traces of carbonic acid disappear within a foot or two of the level of the tuyeres ; we may therefore infer that, in the absence of any subsequent change, the whole of the carbon burnt at the hearth would be given off at the throat as carbonic oxide. Imagine such a furnace filled with coke, along with a neutral substance, such as slag, not liable to any chemical change. Fire is communicated below, and the blast applied. Combustion rapidly sets in, and the gases, as they arrive at the top, soon become sensibly * " Principles of the Manufanture of Iron and Steel," p. 62. t " Chemical Phenomena of Iron Smelting," pp. 8 and 9. NATURE OF COMBUSTION IN BLAST FUENACES. 473 warmer. Their temperature will continue to rise until, at the rate at which the furnace is driven, the refrigerating influence of the cold materials as they enter establishes a position of heat equilibrium, and the mean tempera- ture of the gases will then remain stationary. It is easy to note the time when this occurs, and to observe the exact quantity of coke which has been burnt between this epoch and that at which the blast was laid on. The number of heat units evolved by burning this weight of coke is easily com- puted, and along with it the weight of gases which has been generated by its combustion. The mean temperature of these gases having been noted, we can ascertain with tolerable nicety the quantity of heat they are carrying away with them. The difference between the two sets of figures represents the quantity of heat intercepted by the incoming materials." The amount of this difference was ascertained by Sir I. L. Bell on two occasions* when "blowing in" a furnace, and found to be such that, for every calorie originally evolved in the hearth by the direct combustion of the fuel, 2.33 calories were brought back thither by the materials descend- ing from the upper region of the furnaces, and he gives the following state- ment of the heat development in the hearth per unit of carbon consumed therein : — Heat Calories, I unit of carbon burnt at the hearth to carbonic oxide gives . . . 2,4.00 Heat imparted to the gases by the combustion of preceding units of carbon, which heat, being intercepted by the descending materials, is returned to the hearth in the ratio given above — viz., 2.33 to i — and gives . 5,592 Together 7,992 " Practically, therefore," adds Sir L. Bell, " the combustion of a unit of carbon burnt to carbonic oxide in a blast furnace of 80 feet gives nearly as good an effective result, although it evolves only 2,400 calories, as the same quantity of carbon burnt to carbonic acid in a low fire, although, in the latter case, 8,000 calories per unit of carbon are generated. There is, how- ever, this marked difference between the two examples, that whereas the 7,992 heat units referred to in the case of the blast furnace are almost all usefully employed, a very large proportion of the 8,000, evolved in the low hearth escapes into the air unutilized. In the low fire, as experience tells us, there is an enormous waste of heat, which is indeed visible in the flame and incandescence at the surface of the fuel. On the other hand, in a blast furnace of 80 feet the materials are, it is true, red hot for more than 50 feet above the hearth, but the upper surface of the materials, instead of being red hot, exhibits little or no signs of incandescence, proving a com- parative freedom from waste due to this cause." The temperature of the escaping gases, and therefore the amount of waste of fuel from imperfect utilization of its heat, is regulated to a great extent by the size and capacity of the furnace. Not wholly, however, because the reduction of oxide of iron by means of carbonic oxide is a chemical action, which has been proved in the blast furnace to be of a heat- producing character, so that either the quality of the ferric oxide or the period of contact between it and the carbonic oxide may decide the tem- perature and quality of the escaping gas, and, consequently, the quantity of fuel used in producing iron. Sir I. L. Bell takes t the case of " two furnaces of equal capacity, each fed with a different kind of ironstone and driven at exactly the same speed. If both varieties of ore lost their oxygen at the same rate, reduction in each case would be performed in the same way, so far as regards its being effected by carbon or carbonic oxide. If, on the other hand, one of the ores were * " Chemical Phenomena of Iron Smelting," p. 293. t " Principles of Manufacture of Iron and S^eel, " p 82. 4/4 USEFUL HEAT IN BLAST FURNACE GASES. much less susceptible than the other to the influence of the deoxidizing agency at work in the higher zone of the furnace, then, in any given time, a larger proportion of such ore would descend unreduced ink) the region where reduction is carried on by solid carbon, and would therefore be accom- panied by a waste of fuel." In " illustration of the loss arising from a diminution in the quantity of carbon escaping as carbonic acid in relation to the iron produced," Sir Lowthian Bell assumes " the case of an easily reducible ore, the heat re- quirements of which may be estimated at 96,000 calories per 20 units of pig-iron produced. " If in such a case we hav6 6 units of carbon per 20 units of iron in the gases as carbonic acid, we should have — Calories. These 6 units of carbon x 8,000 calories . . . . = 48,000 Leaying 20 „ to escape as carbonic oxide burnt with air at 0° C. x 2,400 . = 48,000 Total 26 „ making together the . . . 96,000 Included in these 96,000 calories we may assume 12,000 to be carried off in the escaping gases. " Let us now suppose that another variety of ore, resembling the pre- vious one in everything but in readiness with which it parts with its oxygen, to be treated in a furnace of the same "capacity as that used in the former case. As a consequence, it is assumed that by the time it is half reduced a zone of the furnace is reached of such a temperature that carbonic acid is immediately decomposed by heated carbon. Granting that we have now only 3 units of carbon per 20 units of pig-iron escaping as carbonic acid, the account will stand thus : — Calories. The 3 units of carbon as carbonic acid x 8,000 . . . = 24,000 Leaving 30 ,, „ oxide, burnt with air at 0° C. to provide the re- mainder X 2,400 . . = 72,000 Total 33 „ „ making .... 96,000 The difference, 33 — 26 = 7 units of carbon, is not, however, the full measure of the loss : because, not only is the volume of escaping gas much larger than in the former instance, but it is also carried off less perfectly cooled than it was when smelting the more reducible ore. It might therefore easily happen that i J to 2 units of fuel might disappear in this way, bring- ing up the difference to nearly half a ton of coke per ton of iron, and all owing to there being a diminution of 3 units of carbon as carbonic acid in the gases." In answer to the question, in what way can the heating of the blast produce an effect resembling in character that consequent on an enlarge- ment of the furnace. Sir I. L. Bell says : " Let us assume that in a furnace of the olden type — say 50 feet high, and containing 6,000 cubic feet, blown with air at 32° F. (0° 0.) — 35 cwts. of carbon per ton of iron was burnt at the tuyeres, while in another, driven with air at such a temperature that 15,000 heat units per ton of iron entered the furnace with the blast, only 25 cwts. of carbon was consumed in the hearth. " The heat development in the cold-blast furnace at the tuyeres when carbonic oxide only is generated would be 35 x 2,400 = 84,000 units. Calories. With hot air the heat development also at the tuyeres is 25 X 2,400 . . . . . = 60,000 Add heat in the blast 15,000 Total . . 75,000 units. EELATION BETWEEN SOLIDS AND GASES IN FUENACES. 475 But the volume of gases nonveying through the materials the 84,000 calories produced by the cold air is 40 per cent, larger than that which is the vehicle of the 75)000 units produced by the hot air. "It is therefore certain that the retarded rate at which the gases must pass upwards in the latter instance will enable them to impart a larger quantity of their sensible heat to the cold materials, and will afibrd the carbonic oxide a correspondingly longer time to act on the ore than can be the case with the larger volume." Practical illustration of the correctness of these deductions was afforded by the results obtained at some furnaces belonging to Earl Granville, where "prolonged exposure of the solids to the gases was obtained, not by diminishing the volume of the latter, but by increasing the height of the furnace to 7 1 feet, when precisely the same economy of fuel was obtained with cold blast in the enlarged furnaces, as if heated air had been used in those of the olden type, say of 6,000 cubic feet capacity." One ton of metal was made at these furnaces under the following con- ditions : — Cwts. of Coke. Cold blast in a shiall furnace, of say 50 feet, with about 40^ Hdt blast in a small furnace ■ I m, 1 f 01 Cold blast in an enlarged furnace J ''"■'' ^""""^ ■ • ^'** Sir I. L. Bell concludes that hot air and increased capacity of furnace mean one and the same thing, and quotes another result to confirm it. " In the hot-blast, furnace of 6,000 cubic feet capacity the air may be con- sidered as having been heated to about 1,000° F. (538° C), but when the temperature was raised by means of fire-brick stoves to about 1,400° F. (760° C), and this was applied to a furnace of 7,500 cubic feet, the con- sumption of fuel was the same as that in a furnace of about 11,500 cubic feet blown with air at 1,000° F. (538° C.)." Elsewhere* Sir I. L. Bell has I'emarked that " independently of any increase of temperature in the upper portion of the furnace, the use of hot blast introduces a change in the relation between the solid and gaseous con- tents, which will have the effect of accelerating the tendency towards an equali- zation of the temperature of the two. By this action, the ore is more speedily heated, and the gases, in consequence, are more quickly saturated with oxygen. This arises from the longer retention in the furnace of the carbonic oxide evolved by the combustion of a given weight of coke," when it is burnt with hot air, as compared with its combustion with cold air. Thus, if a furnace of 6,000 cubic feet capacity receives 14,400 cwt. heat units by means of hot blast, " this is equal to the heat from 6 cwts. of carbon burnt to carbonic oxide, which carbon can therefore be at once withdrawn from the fuel introduced with the charges. This quantity of carbon represents 38.8 cwts. of gases, which is equivalent to about 10 per cent, in volume of those flow- ing up through the contents of a furnace using originally 60 cwts. of coke per ton of iron. During the time, therefore, each cwt. of carbon is engaged in fusing the iron and slag in the hearth, while in the act of being con- verted into carbonic oxide, the carbonic oxide thus formed is retained by the diminution of its volume one-tenth longer in the furnace, and by so much its contact with the materials the gases have to heat and to reduce is prolonged. This effects a further saving of fuel, and in consequence a further reduction in the volume of gas is accompanied again by an addition to the time of retention of this gas in the furnace. This is cohtinued until the fuel is diminished in quantity, as far as a furnace of the proper dimen- sions is capable of producing a ton of iron, which is not reached until the gases in bulk are a trifle above one-half of what they were when the blast • "Min. Proo. Inst, C.E.," vol. xxxiv. part ii. 476 ADVANTAaBS OF HOT BLAST. consisted of cold air instead of with the supposed addition of 14,400 heat units." It is clear that under such circumstances the reducing gases will be twice as long in contact with the ore they have to reduce and with the materials they have to heat as when cold blast is employed, and the instances previously quoted show that it is time rather than any mysterious quality of hot blast which effects a change in the saving of fuel in a blast furnace. In fact, supposing a furnace having " sufficient capacity to permit the two functions of fusion and reduction to proceed in point of time in unison with each other, instead of one heat unit in the blast doing the work of three or four previously evolved by the fuel, each unit of heat thrown in with the air does no more duty than one unit produced by the combustion of coke inside the furnace." There are, however, practical advantages in the use of heated blast which must, to some extent, outweigh strictly calorific considerations. Thus, as Sir I. L. Bell points out, " conveying heat into the furnace by means of the blast enables the smelter to pour in a supply where it is most required, without waiting for any change in the burden of coke and ironstone which come down into the hearth." Again, the air may be heated by fuel of greatly inferior value to that which is used in the furnace itself. " The fuel used in heating the blast is the gas which escapes from the furnace, which in many, indeed in most, cases would be wasted, but may at the best be valued as small coal, which, in the North of England, can be had for three- pence per cwt. If, then, by burning 2 cwts. of coal worth sixpence, or, still better, by burning furnace-gas costing nothing, 3 cwts. of coke, worth, it may be, two shillings, could be saved, a great gain would arise from such a change." In addition to this, the use of hot blast must have the advantage over even an equivalent increase of capacity beyond a certain point, because, when the height of the furnace is carried beyond the limit, soon fixed by experience as the most suitable for working conditions, the weight of the burden inter- feres with the proper condition of the materials, compressing and even crushing the portions most easily friable, and oflfers resistance to the passage of the gases and blast through a lofty column of solid minerals. Sir I. L. Bell also remarks that, "strictly speaking, some small allowance must be made in favour of superheated air, owing to the diminished volume and some- what reduced temperature of the escaping gases, consequant on the reduced quantity of carbon burnt by the blast, and the smaller quantity of carbonic acid per 20 units of iron which is generated at the top of the furnace." The facts that, by increasing the temperature of the blast, the quantity of solid carbon charged into the furnace is reduced, thus diminishing the quantity of useful gases produced, and that the zone of high temperature is carried to a greater height in the furnace, thus causing interference with the reducing operations, show, however, that the conditions of the smelting process themselves impose limits on the elevation of blast temperature, even in spite of economy of fuel. Sir I. L. Bell shows that theoretically the reduction of iron ore and carbon deposition arising from dissociation of carbonic oxide limit the carbon escaping as carbonic acid from a Cleveland furnace to 6.58 units per 20 units of pig-iron. Practically, however, more or less of this carbonic acid is wanting. A very common quantity would be 5.58 units, which means a deficiency of 5,600 calories where 86,000 calories in all are required. Stating the two cases, we have : — Units. Units. Carbon as carbonic acid . 6.58 . . . 5-5^ By oxidation of carbon, calories 80,528 1 o-- „ „ f 74,928 ] o/:-,^ In hot blast „ 5,472 r^'°°° 1 11I072 1 ^6'°°° PRACTICAL LIMITS OF HEATINa BLAST. 477 Sir I. L. Bell says " this statement is intended to prove that, if the carbon fails to perform its full theoretical duty, the deficiency in the instance cited is made up by additional heat of the blast ; but it is equally true that the more heat contained in the blast, the larger must be the quantity of carbonic acid which disappears from the gases per 20 units of iron made, because the heat so conveyed into the furnace is intended to displace, and does dis- place, so much carbon introduced as coke ; and, as the two oxides of carbon have to be maintained in certain relations to each other, it is obvious that we cannot, when the two are found in these relations, alter the quantity of the one without at the same time producing a rateable effect on the other." In order to show the temperature of blast necessary for its substitution for coke as successively smaller portions of carbon are burnt for heat pro- duction, where the carbon as carbonic acid is to that as carbonic oxide in the resulting gases as i to 2, and where 86,000 calories are required per 20 units of iron made. Sir I. L. Bell gives the following figures : — Carbon burnt % Blast. 18 17 l6 15 Weight ot Blast. Burnt to Heat jiroduced by Total from Carbon. Blast to provide 9,200 13.448 17.752 22,000 Total Heat. Temp, of Blast. COj, (Xh COj. CO. Deg. C. Deg. F. 701 1,069 1,486 1,954 104.3 98.5 92.7 86.9 6.00 5.67 5-33 5- 00 12.00 11-33 10.67 10.00 48,000 45.360 42,640 40,000 28,800 27,192 25,608 24,000 = 76,800 = 72.552 = 68,248 = 64,000 = 86,000 = 86,000 = 86,000 = 86,000 372 576 808 1,068 Corrected for 00^ to CO as i to 2.22, the figures become : — 18 74.504 11,496 =86,000 465 869 17 70,368 15,632 =86,000 669 1,236 16 66,232 19,768 = 86,000 900 1,652 IS 62,040 23.960 =86,000 1,163 2,152 It is not likely, however, that the highest temperature, namely, 2,152° F., will be attained in practice, from the fact that it is almost impossible to find a material capable of withstanding such a temperature in regular work, and consequently Sir I. L. Bell adopts 1,600° to 1,700° F. as a practicable point to be attained, and gives the equivalent consumption in coke (using about 12 units of limestone for smelting Cleveland ironstone) as follows: — Units of carbon per 20 unils of iron burnt with blast at 1,652° F. . 16.00 Carbon burnt by carbonic iicid in limestone 1.44 Carbon in iron . . 0.60 Add for impurities to 18.04 carbon to bring it to coke, say 7^ per cent. 18.04 '■35 1939 He remarks on this, " It must not be supposed that this weight of coke is unchangeable, as it is susceptible of some trifling modification arising from differences in the richness of the ore or of the quantity of flux required. With this qualification, 19^ cwts. of coke may, in my opinion, be accepted as the possible limit with which a ton of Cleveland foundry iron will be pro- duced using air at a temperature of nearly 1,700° F. If so we have a gain of I cwt. of fuel or thereabouts, as compared with the case when the blast is heated only to 1,000° F." H. Schellhammer * has investigated in a very careful manner the influence of pressure of blast on the working of blast furnaces, and more especially the relation of the pressure and quantity of the blast to the con- sumption of fuel and the composition and temperature of the gases. " Oest. Zeit. fur B. u. H., No. 35, et seq. ; " Jour. Iron and Steel Inst.," vol. ii. 1882, p. 745. 478 INFLUENCE OF PRESSURE ON EFFECT OF BLAST. His results and calculations are embodied in several tables and diagrams of considerable interest, but his conclusions are not beyond question. Generally it appears that increase of pressure — involving increase of quantity of blast per minute — is accompanied by a smaller consumption of fuel and a higher temperature of the gas, which means a higher temperature throughout the furnace and a larger zone of indirect reduction. With a low pressure, the blast does not penetrate into the centre of the hearth, but rises along the sides of the furnace. As a consequence, a column of imperfectly reduced ore mixed with charcoal comes down in the centre, and has to be reduced directly by solid carbon. As only a part of the ore is acted on by a very great body of gas, a large quantity of carbonic acid must remain inactive and escape without being further oxidized. With increased pressure, the blast penetx'ates deeper into the crucible, the column of imperfectly prepared ore will be less and the quantity of carbon used for direct reduction is diminished. The absorption of heat which accompanies direct reduction will also be less : therefore the temperature at the tuyeres and in consequence the temperature of the whole furnace will rise. The gas, although up to a pressure of 190 millimetres it is less in quantity and richer in carbonic acid, acts on the ore within a larger space and at a more favourable temperature, and is so enabled still to perform its duty. Herr Schellhammer lays particular stress on the reaction by which carbonic acid (exclusive of what is introduced as carbonate in the ore and as a- gaseous constituent of the charcoal) is formed, whether by direct reduction of ore in the lower parts or indirectly by oxidation of carbonic oxide in the upper parts of the furnace. He calls these two quantities D and I respectively, and expresses their proportion by — in his tables of results, but although the most economical consumption of fuel ought theoretically to be expected when — = o, viz., when no direct reduction takes place, in fact the minimum of fuel in his results is found when D — = .200. HEATING BY -WATEB AND STEAM. Water ana steam are frequently employed as carriers of heat, for which purpose they are particularly well adapted, in consequence of the high specific heat of the former and the large quantity of latent heat contained in steam. According to De la Roche and Berard, the quantities of heat contained in equal weights of water and air at the same temperature are in the ratio of 374.6 : 100; or the heat which is liberated when water cools down 100° C. is sufficient to raise the temperature of 3.74 times as much air to the same amount. Regnault's results correspond with the factor 4.21, giving even a larger heating value. We have here, therefore, an analogous case to that of clay ; the heat destined for a given quantity of air can be retained or accumulated in a much less quantity of water ; and a still greater effect is produced when water, in the form of vapour, is made the purveyor of the heat. In passing into the state of vapour, water absorbs 5. 36. times as much heat as is required to heat it from 0° to 100°, and this quantity of heat producing no increase of temperature in the steam, it cannot be recognized by the thermometer, but again becomes sensible when the vapour is condensed. Consequently, i lb. of vapour at 100° (212° F.) will, in con- densing to form boiling water, give off sufficient heat to raise the temperature of 5.36 lbs. of water, or 4.21 x 5.36 = 22.6 lbs. of air to 100° (212° F.). When warm water is employed, it must necessarily be renewed in pro- HEATING BY WATER AND BY STEAM. 479 Fjg. 328. portion to the amount of heat required, and, to avoid the trouble of constantly changing the water, a certain portion is caused to circulate in such a manner as to keep up a continuous ascending current of warm, and a descending current of cold, water. Fig. 328 shows the principle of the circulation. The heat applied to the bottom of the vessel a is first communicated to the lower layers of water, which, becoming expanded and specifically lighter, rise to the higher parts of the vessel ; they ascend to h, from thence into the tiibe c, and lastly to d. In proportion as these portions rise, however, the cold water descends in e, and this circu- lation is kept up as long as any difference of temperature exists in the different parts of the apparatus, a condition which is con- stantly maintained by the cooling of the water in its passage. It is obvious that a may be an open vessel, into which the ends of the tube dip like a siphon, but then much heat will be lost. The heat itself, in this arrangement, is the motive power for producing the circulation, which is so much the more rapid the fewer cooling and other obstacles are placed in the way of the ascending current. In this country, where the system of heating by water was introduced by Per- kins, closed coppers are used, which can be heated in the same manner as steam boilers ; or the pipes themselves, without any boiler, are carried through a stove in numerous coils. The dimensions of the fire and the conducting pipe must be well proportioned to each other, so that the cooling takes place rapidly, and no steam is formed. To .avoid all danger from explosion, which a sudden burst of steam might possibly occasion, safety-valves are introduced, and compen- sating pieces, to prevent the bursting of the metal tubes by sudden expan- sion and contraction. The latter danger is guarded against by connecting the ends of the pipes with a stuffing-box, instead of with screws, thus com- bining mobility with a water-tight connection. Tubes are also provided at the top of the conducting pipes, as at m, for the escape of the air, which is evolved on heating the water. The quantity of water which is to be conveyed per minute from the apparatus to the space to be heated can be determined in the following manner. If A represents the number of cubic feet of air, at a temperature of t° warmer than the external air, which have to be supplied per minute ; and if i cubic foot of water is 770 times heavier than i cubic foot of air, then A cubic feet of air correspond with cubic feet of water by weight ; but the heat which raised the temperature of A to t° is only capable of raising the ^th of this - — , or, more correctly, , to the same tem- * 770 4.21 X 770 perature ; in other words, cubic feet of water in cooliner f will 4.21 X 770 ^ raise exactly A cubic feet of air to the same temperature. But the water in the pipes has a temperature of nearly 100° 0. (212° F.), and gives off 48o HEATING BY STEAM.— CONDENSATION. from 60° to 70° of this, or cools {T—t')°; therefore, as much less water will be required as {T — t')" is higher than f, namely: it" A t° " —-- -H= 77= — TTa-Q cubic feet = 62. %2 lbs. 4.21 X 770(2'-*')° 3,24i.7(2'-0 ... of water per minute. It is necessary to know the velocity with which water moves in pipes, in order to construct the conducting pipes of proper dimen- sions.* The determination of this is the same in principle as that of the draught in chimneys, the friction of the water being somewhat different from that of the air. The velocity, together with Q, gives the diameter of the pipes, and the latter the dimensions of the fire. The ascending pipe is straight, and surrounded by badly conducting substances, to prevent cooling ; the descending pipe, on the contrary, is furnished with every facility for com- municating heat to the air of the room. When the heat is to be communi- cated to a very extensive space, the water becomes too cold in the more remote rooms, and a separate set of pipes for each half of the building is desirable. Steam heats much more effectively than water, and consequently less of it is required. As 24.6 cubic feet of air at 0° weigh i lb., then A cubic feet ■ A in the former equation will weigh — - lbs., and will be heated by the conden- 24.0 A sation of lbs. of steam of 100° C. (212° F.)in forming boil- 24.6x4.21x5.5 A t° ing water (of 100° C), and consequently by = Q lbs. ^ ^ " ^ 1 •'24.6x421x5.36x100 ^ of steam to t° higher than the temperature of the external air. The pipes destined to carry the steam to the place of condensation are chosen of narrow bore (about 1.5 inch), and, to avoid all condensation during the transit, are surrounded with a thick covering of felt, woollen cloth, or other bad con- ductor of heat ; the condensing pipes are of copper or ca.st iron, at least four times as wide, and must be so arranged that the air can escape when the steam iS first admitted, or this would otherwise very much retard its dis- semination. These pipes should be rough and not polished, and the copper tubes should be painted or stained so as to give them the appearance and the properties of cast iron. To allow for the expansion in length, the same plan may be adopted as in water-pipes, or simply a h&a,t piece of flexible metal may be inserted into the course of the tube, which by bending to a greater or less degree, compensates for the expansion. It is found that different bodies condense steam in a very unequal manner, according to the nature of their surfaces and to their co-efficients of conductivity. Tredgold found the following quantities of steam condensed per hour by a square foot of surface of the different substances in the form of pipes exposed to a tem- perature of 59° F. : — Tin-plate 0.185 lb. Glass . 0.333 New sheet-iron . 0.340 Busty sheet-iron . 0393 Clement further observed that, at a temperature of 15° 0. (59° F.) in the surrounding air, i square foot of surface of horizontal cast-iron pipe would condense 0.234 lb. of vapour, of bright copper pipe 0.184 lb., and of blackened copper pipe 0.213 lb., which quantities are somewhat increased by a perpendicular position of the pipes. Whatever form is given to the apparatus, ample means must be afforded for the removal of the condensed water, and a special set of pipes, conduct- ing it back to the boiler, is generally employed for this purpose. Occasion- ally, a quantity of water is expressly left in the pipes after circulation has * Eefer to "Proc. Inst C.E.," vol. xii. pp. 25-109; vol. xiii. pp. 64-120; vol. xiv.. J. Leslie, "On the Flow of W*ter through Pipes;" vol. xviii. pp. 363-403; .ind art. Hydro- mechanics, " Encyclopsedia Brif.," vol. xii. EMISSION OF HEAT BY HOT- WATER PIPES. 48 1 ceased, that the accumulated heat (as in clay stoves) may be obtained. In order to prevent any sudden or unexpected powerful condensation drawing up the water from the boiler, there must be a valve, opening downwards some- where about the spot where the vapour enters the system of pipes. There is a greater loss of heat, oh account of the larger dimensions of the pipes, when air is made the medium of transmission, than when either water or steam is employed, while the latter are not so well calculated to assist ventilation. When water is employed as the heating medium, the apparatus is, on the whole, simpler, the temperature more easily regulated, and not so suddenly elevated as by the use of steam ; the latter, however, will convey the heat to much greater distances, and can be employed to heat the uppeS? floors of lofty buildings, where the pressure of columns of water would prove very inconvenient. The diameters of the condensing pipes, when steam is used, must not be too large, or the air is expelled with difficulty ; nor too small, or the friction wiU impede the passage of the steam, and diminish its tension. They may vary from 3 to 8 inches in diameter, and the best manner of supporting them is by iron rods fixed to the ceiling. The Emission of Heat by Hot-water Pipes. — Some very interesting experiments and observations on the emission of heat by hot-water pipes are recorded by Mr. W. Anderson in Min. Proc. Inst. C.E., vol. xlviii. p. 257. He remarks that Prof. Balfour Stewart in his Elementary Treatise on Heat (articles 229—235 and 285-287) gives a clear explanation of the process of cooling by radiation and convection, in which he quotes Dulong and Petit's formula as modified by Hopkins, according to which the total amount of heat radiated per square foot per hour may be found by the expression — m X a*(a'— i), and the heat carried oflf by convection in atmospheric air by the formula — o.o372('-^)°"x«'!!33 V720/ ' in which fls= 1.0077 6 = temperature of the air surrounding the pipes i = difference of temperature between the air and the pipes, both temperatures in degrees C. p = height of barometer in millimetres OT = a co-efficient of radiation. Mr. Anderson's experiments were undertaken for the purpose of deter- mining the co-efficient m for the usual hot-water pipes employed in practice. Reduced to British units and 30 inches height of the barometer, the formula becomes — M = total units emitted per square footi =m x 1.00427^(1. 00427*— i) per hour by radiation and convection \ + 0.2853 ^ *'''"') M-o.2853x«'-2»s whence m = jt , r. 1. 0042 7''(i. 00427'— i) " The method adopted for obtaining m was to raise a coil of iron pipes of known weight, and containing a known weight of water to a certain tem- perature, then allowing it to cool while observing the temperature at equal intervals of time. " Thermometers were inserted into the pipes at the upper and lower ends of the coil, and precautions were taken to guard against accumulations of air in the pipes and other disturbing causes. The time of cooling and the fall of temperature being thus ascertained, the number of units of heat 482 CO-EFFICIENT OF RADIATION FOE HOT-WATEE PIPES. emitted was easily calculated, and the value of m determined, not only for each experiment during the whole process of cooling, but for intervals of about one hour in each case. To make sure that no serious errors of observation had been committed, the fall of temperature was plotted in curves, in which the abscissae represented the time, and the ordinates the temperature of the air as well as that of the pipes." Mr. Anderson states, as a result observed in his experiments, that " a considerable error is committed by assuming, as is commonly done, that the mean temperature of a coil is the arithmetical mean of the extreme temperatures. For example, for a coil of 4-inch pipes the true mean tem- perature in cooling from 69°.S down to 2^°.'j is 40°. 52, while the arithmetical mean is 46°. 6. It is obvious, supposing hot water to be flowing through the coil so as to cool to the same extent during its passage, that the mean temperature would have to be ascertained by a curve in the same way." The results of eight experiments are given in the following Table. The 2-inch coils forming the subject of the first five experiments were made of common galvanized pipes, connected together by galvanized wrought-iron elbows. The coils were not covered by a casing, and were placed in a boiler- house tolerably well protected from draughts. Values of Co-efficient m of Radiation in the Forrmda u = mx 1.004279(1.00427 — i) -t- 0.285 '^ *'"'' Derived from Experiment I. 2. 3- 4- 5- 6. 7- 8. Ksperiinents. 1 go .11 0.b i 0] So m §S.6 II s.| u 111 is of Heatjper sq. for 50° Differeni-e, Air Temperature calculated. a ^ ^ II &P Hours. DegreeB. Degrees- Degrees. Degrees. Degrees. I. A single coil of 2-inch g-al- vanized-iron pipes ; heat- intr surface, 25.949 eQuare feet. Weight of iron in coil, 205 lbs ; weight of ' water contained in coil, S3 lbs 3.500 206.00 51 so 103.00 51.50 143.0 270.90 IT9.IO 2. A single coil, same as No. i. but with a vertical sheet of iron between the pipes 3-833 205.00 50.13 100.28 50.15 J44-5 252.90 113.50 3. Single coil, same as ^'o. 1, blaekleaded 3-833 206.00 52.90 103-75 50.85 143.3 241.00 109.90 4. Single coil» same as No. 2, and blaekleaded in addi- tion 3-583 205.09 52.27 106.07 S3- 80 140.5 23530 108.10 5. Siuifle coil, same as No. i. with^a second similar coil placed ne&t to it 3-833 202.00 52.62 103.66 51-04 138.0 231.80 107.20 6. A coil of 4-Inch cast-iron pipes, 87 square feet sur- face. Weight of cast iron. 1,564 lbs. ; weight of water contained, 265 Ibg. . 4-033 133.00 59-75 102. 1 1 42.36 47.8 121.70 73.00 7. Coil of 2-ineh cast-iron pipe in room of ironworks office. blaekleaded, uncased ; sur- face, 34.2 pquare feet. Weight— east iron, 318 lbs.; water, 64 lbs. . 3.000 130.50 61.50 98.50 37 -oo 53-2 12303 73-44 8. Same as No. 7 4.000 133-50 61.40 95-8o 34-45 61.7 108.80 69.00 9 and 10. Battery of 2-inch wrought-iron tubes, con- necting two cast-iron st^am 1. 000 282.00 58.71 282.00 223-30 - 272.30 chests, heated by 36 lbs. steam ; 232 square feet of 1. 000 282.50 59-50 282.50 223.00 - 262.90 surt'acB .... EXPERIMENTS WITH HOT-WATEE PIPES. 483 The effect of placing a piece of sheet-iron vertically between the two rows of pipes and of blackleading and brushing the pipes, was to reduce the rate of cooling. A second coil placed beside the first retarded its cool- ing only 10 per cent. The 2-inch cast-iron pipes were old, but the 4-inch and 2-inch wrought-iron pipes were new. " An examination of the formula shows that radiation only is affected by the temperature of the atmosphere, and that the emission of heat is greater as the temperature of the air increases. Taking the case of the 4-inch cast-iron pipes, with m=i22, a constant difference of tempera- ture, i=5o°, the total heat emitted per square foot per hour becomes M= 29.13 X 1.00427*-!- 35.46, and solving for 6, the temperature of the atmosphere ranging from 32° to 60°, the following result is obtained : — Temperature of air, 6= I 32° I 39° I 46° [ 53° I 60° Total heat units, M = | 68.87 I 69.89 | 70.94 | 72.01 | 73.13 " The difference of emission between the extremes is only 4.26 units, or a little over 6 per cent, more at 60° than at 32°. As, for the purpose of warming buildings, the air in the rooms is generally taken to be at 60°, and as any small variation from that temperature will not affect the rate of cooling much, two curves may be calculated for 4-inch cast-iron and 2-inch wrought-iron pipes with the co-efficient of radiation 122 and 250 respectively (the mean of the several values of m), which will enable the total units of heat given out per square foot of surface per hour to be ascertained by inspection for any difference of temperature. Fig. 329 gives these curves. " Suppose, for example, it is required to know how much heat will be given out by 4-inch pipes at 190° in a room, the temperature of which is 60°, the difference of temperature being 130°; look along the line of abscissae for 130, and the ordinate then gives 232.7 units for 4-inch pipes and 356 units for 2-inch wrought-iron pipes per square foot per hour. " The heating surface necessary to warm a given building depends on a variety of circumstances— on geographical position, whether the house stands high and exposed or low and sheltered, and whether the average winter temperature is high or low ; on the thickness and material of walls ; on the area and construction of windows, and so forth. Very little can be done by calculation ; the area as well as disposition of the pipes must be a matter of judgment." A Table showing what has been done in one or two buildings is given by Mr. Anderson, from which, he says, "it would appear that for ordinary dwelling-houses i square foot of surface is necessary to every 65 cubic feet of air to be heated, and in a greenhouse i square foot to every 24 cubic feet of air. " When the water circulates through the pipes by virtue of the difference of temperature of the flow and return currents only, it is impossible to count upon a greater mean temperature of the pipes than from 160° to 180°, because above that temperature the water in the boiler begins to boil, and causes an overflow of the supply cistern and escape of steam at the air- pipes. " When- forced circulation is adopted— ^as, for example, at the Third Middlesex County Lunatic Asylum at Banstead, near Sutton, where the water is propelled by a centrifugal pump, and where it is under a pressure of about 70 feet — a much higher temperature can be attained. One of the advantages in heating by steam is the high temperature that can be obtained in the pipes, but the disadvantage is that it is difficult to moderate the temperature in warm weather." Mr. Anderson at one time thought that pipes heated by steam might possibly emit heat more quickly than those warmed by hot water. Some 112 484 CURVES OF HEAT-UNITS GIVEN OUT BY PIPES. experiments which were made in 1870 on a tubular steam heater, however, showed that the rate of emission was as nearly as possible the same as with tubes of the same size heated by water. " The heater consisted of fifty-nine 2-inch wrought- iron tubes 6 feet 5 inches long connecting two cast-iron steam chests 7 feet long and i foot 3 inches wide. " The heating surface of the tubes was 197 square feet and of the steam chest 35 square feet, or 232 square feet in all. By means of diaphragms in the chests the steam was made to circulate through the pipes." Two experiments of an hour's duration each gaye the weight of steam that could be condensed. The result was that i84'| and 180 lbs. of water were drawn off in the two experiments. From this it followed that 785.7 and 766.5 HEATING BY STEAM. 485 units of heat per square foot per hour must have been given off, and that the co-efficient of radiation must have been equal to 272.3 and 262.9, °^ nearly the same as that derived from the 2-inch wrought-iron water-pipes. Fio. 330. One of the best modes of employing Steam is shown in Fig. 330. There is only one pipe through which the steam ascends from the boiler, and also only one extensive coil of pipe by which the condensed water returns. This arrange- ment is better than those in which the steam enters a number of pipes simul- taneously, for it is difficult in the latter case to remove the air perfectly from all the pipes. A cock for allowing the air to escape mustbe introduced at the top of the pipe, but this is not shown in the drawing. When placed in the locality to be heated, the above appara- tus becomes a steam-stove. If at a distance, and surrounded with a case, through the bottom of which air enters, the warmed current of air may be transmitted to a higher position. • If the diameter of the pipes is small, the length must be increased in proportion to afford a sufficient heating-surface. The pipes may be of copper or iron ; the latter are cheaper, and require no ad- ditional support. It is always desirable to conduct the^j condensed water again to the boiler ; heat is thus economized, and the incrustation of the boiler and pipes, which often proves a very serious inconvenience, is prevented. The new Infirmary in Edinburgh is heated by means of a svstem of uncovered pipes and coils containing-low pressure steam, the radiation from the hot surfaces and also the transference of heat by contact and convection of air currents serving to warm the air of wards and passages, whilst the condensed steam is collected in return water pipes by which it is led back to the boiler-house and is there again utilized in the boilers. • 33i- There are three steel cylin- drical multitubular boilers of 5 feet 6 inches diameter, and 15 feet long, devoted to this heating system. These have the furnaces placed underneath, the hot gases returning through about 60 return tubes of 2 ^ or 3 inches diameter, whence they pass along flues running along- side the boilers and escape to the chimney. The boilers are worked at about 10 to 20 lbs. pressure per square inch, and the total area in steam pipes, coils and return water pipes throughout the infirmary buildings is about 17,000 square feet. 4.86 PERKINS' HOT-WATER SYSTEM. Pia. 332. The average temperature of the water returned to the receiver at the boiler-house is usually about 140° to 150° F. A similar system of heating was installed at St. Paul's Schools, West Kensington, London, in the year 1885. Price's hot-water stove for heating air, which is used in many public establishments in this country, is shown in Fig. 331. The heating-surfaces are constructed of square cast-iron boxes, placed vertically, affording about 3 feet surface, and connected at two of the opposite angles with horizontal pipes. The joints are secured with collars of iron-wire gauze and red putty, which stand remarkably well. The boilers may be heated with a continuous supply of anthracite in the manner described below (vide Evaporation). The hot-water system invented by Mr. Perkins, which is shown in Fig. 332, was introduced into the British Museum, is arranged on a different plan. The ap- paratus consists of a circuit of pipes of small diameter, surmounted by an herme- tically closed expansion vessel ; the lower portions of the circuit pass in several coils through a furnace, where the water be- comes heated to a very high temperature. Fig. 333 represents the general ar- rangement of one of these coiLs. The water ascends by a single tube from the furnace, and descends in two tubes, each of which forms two helices at different elevations. The tubes are about an inch in diameter, very thick, and capable of withstanding a pressure of 3,000 at- mospheres. A force-pump is employed in filling the tube with water, which completely expels the air and at the same time affords an opportunity of testing the strength of the apparatus up to a pressure of 200 atmospheres. The tubes are screwed together in such a manner that the somewhat tapering end of the one enters the flat metallic surface of the other. It has been found by experience that the portion of the circuit heated by the furnace should not be much less than ^th of the entire length. In Mg. 333 the coil of pipe is quadrangular, and so arranged in the furnace that the flame heats the one-half in ascending, and the other in descending before escaping to the chimney. Figs. 333 and 334 represent the furnaces as employed at the British Museum. Fig. 333 is a pei-spective view, with the front wall removed, and Fig. 334 a horizontal section. The fire is supplied witbfuel from above ; the smoke and hot ga.ses pass round the entire circuit of pipe before escaping to the chimney. The temperature of the pipes in the highest part of the circuit is generally from 300° to 400° F., and in the lowest part of the descending column it does not exceed 140° to 160° F., which temperatures correspond to pressures of from 4 to 15 atmospheres. In the furnace. PEKKINS' HOT-WATER SYSTEM. 487 Fio. 333- however, the pipes are heated to low redness, and if the water acquired that tempei-ature, which is calculated at 932° F., the pressure would amount to 857 atmo- spheres. On account of the high temperatures co- incident with the high pressures employed, this system has been thought to be danger- ous as a probable source of fire. A Report* drawn up by experts appointed by the Manchester Assur- ance Co. to investigate this matter substanti- ates that opinion. No t w i t h s tanding every precaution, there is a constant loss of a small quantity of water, even when no perceptible leakage can be discovered ; and in extensive coils it is necessary to add about a pint of water every eight or ten days. The total extent of circuit is seldom allowed to exceed 400 to 500 feet, and 2 feet in length is con- _ sidered sufBcient heating - 334- surface for 100 cubic feet of space. Avery admirable system of heating and ventilating by hot water was adopted in many of the public build- ings of France, on the re- commendation of commit- tees consisting of the most eminent scientific men of the day, and was carried out by very able engineers. As one illustration of the system, which is modified according to circumstances, we select from the numerous plans described by P6c]etf • in his Nouveaux documents \ relatifs au chauffage et a la ventUation des etahlissements \ publics, that which was adopted at the Mazas prison. This building was constructed for the solitary confinement of prisoners, whose health and comfort, as far as they are * See " Ou Practical Ventilation and Warming," by J. Constantine. t See also "Practical Treatise on Heat," by T. Box (Loudon ; Spon). 488 HEATING OF THE MAZAS PRISON. dependent on warmth and pure air, were certainly considered with the greatest attention, and in a manner worthy of imitation by governmental boards in other countries. The prison consists of six long stacks of building, each of which is two stories high, radiating from a com- mon centre. The middle of each of these is occupied by a long corridor, extending from the ground floor to the roof, and terminated by a large window. On either side is a range of cells, the capacity of each being about 700 cubic feet. Upon the system of ■ M. Grouvelle, to whom the heating and ventilation of the building were entrusted, the air supplied to the cells was heated by contact with pipes con- taining hot water, which are in con- nection with reservoirs on each floor, where the water was heated by a coil of steam pipes supplied from generators in the basement of the central build- ing. Ventilation was produced by a vast chimney about 40 square feet in section, and nearly 100 feet high, which is also situated in the centre of the edifice. The whole of the air from the cells was drawn by the action of this chimney in a downward direction through a vertical pipe in each cell, which, being in connection with a night-stool, served at the same time for removing excrementitious matters ; the pipes from the sevei^tl' cfeUs ter- minated in an underground vault, whence the vitiated air was drawn off by the chimney draught, while the solid and liquid excrements were col- lected in barrels, to be removed at fixed intervals. A balcony extends along each corridor at the height of I the first and second stories, on to which the cell doors open. Channels were carried below these balconies in which two sets of cast-iron pipes conveyed currents of hot water in opposite direc- tions, by which means a uniformity of temperature was established through- out the entire circuit. On the ground ' floor, this channel was below the floor in front of the cell doors. The chan- nel was intersected by partitions corresponding with the walls of each cell, and the air from the corridor was admitted to the spaces between these partitions by gratings, and thence, after coming into contact *ith a con- siderable surface of pipe, was admitted through several apertures to the interior of the cells. HEATING OF THE MAZAS PKISON. 489 Yig. 335 is a vertical section of one of the buildings, on a plane parallel ■fco the axis, and in part through the middle of one of the side balconies. A is the large wrought-iron reseiToir, in which the water is heated by a coil of steam pipes supplied from the underground generators ; C C are vessels in connection with the systems of pipes to afford space for the expansion of the water. D D the pipes for conveying the fsecal matters and vitiated air from the cells. D' D' apertures for admitting the air of the corridor to the channels containing the hot-water pipes. D" D" apertures for the air to enter the channels situated below the ground floor. E E apertures con- necting the channel with the interior of the cells. On leaving the reservoir, the hot water traverses the single pipe, shown in Fig. 336 ; but on arriving under the first cell, a branch pipe conducts a portion to the opposite side of FiQ. 336. the corridor, so that hot water is flowing simultaneoufly through pipes on both sides, the cooled water returning in the same manner to the bottom of the reservoir. ^ig- 336 shows a vertical section of one of the cellular buildings at right angles to the axis. Each cell is rather more than 1 2 feet long, about 6 feet 6 inches wide, and nearly 10 feet high; each contains a gas-burner and a night-stool C, the descending-pipe from which carries the vitiated air of the apartment into the vault below, which is in communication at the one extremity with the ventilating chimney, and closed by a double door at the 490 HEATING BY OPEN FIEES. other, which is only occasionally used for removing the barrels. The air escapes between the lid and the seat of the, stool from the cells, and through the short appendages on the pipes into the vault ; the longer extremity of the pipe dips into the close barrel ; the air aperture can be stopped by a cap and some hay. A B are the hot- water pipes extending the whole length of the building below the gaUeries, and enclosed in a plastered channel ; the air of the corridor has access to this, and passes warmed into the cells through the apertures D, which can be closed by plates of cast-iron. E windows of the cells ; these are now never opened, in consequence of the great irregu- larity in the ventilation, which resulted from the effects of wind and sun. F is the grated window at the end of the corridor. G expansion-vessels. According to the report of a committee on the whole system of heating and ventilation, the chimney is capable of drawing 1,059,300 cubic feet of air per hour, which, as there are 1,200 cells altogether, is equivalent to 882.7 cubic feet of air per cell per hour, or more than double the quantity required; very careful experiments having proved that 353 cubic feet per hour was amply sufficient to remove all noxious effluvia and establish a thorough current down the ventilating pipes. By means of registers in the subterranean air-vaults, the ventilation can be rendered uniform in all the six ranges of building. The quantity of air actually supplied averaged, during several months, between 529 and 882 cubic feet for each cell in the hour. A temperature of 55° to 61° F. was maintained during winter in all the inhabited parts of the building, and the apparatus was capable of afford- ing more heat if required, only four of the six steam generators having been employed. For the seven months during which artificial heat was required, the mean temperature of Paris being about 43° F. and assuming the interior of the building to have a mean temperature of 57° F., the consump- tion of coal for the production of the difference in temperature of 14° F. was, on an average, 5^ cwts. a day for each of the six stacks of building, and 2 cwts. for the general offices of the prison. The total consumption was therefore s|x6-)-2 = 33^ cwts. a day. For producing the ventilation, the mean consumption of fuel was in summer 8 cwts., and in winter 7 cwts. a day ; but for obtaining a ventila- tion of 1,059,300 cubic feet per hour, the consumption of coal in winter was 44 lbs., and in summer 55 lbs. per hour. In the year 1852, a committee, appointed by the managers of the Infirmary at Newcastle-upon-Tyne, inspected the principal hospitals, both in London and the provinces, with a view to ascertain the best practical method of warming and ventilating such institutions. So universal was the support given to the open fire for heat, and the window for admitting air, that the committee, after mature consideration, agreed to adopt this plan as being more healthy, cheerful, and under better control. The execution was entrusted to Mr. Dobson, architect, who gave the following drawings and description of the plans carried out by him, which were eminently successful. The wards are double, each of them 106 feet by 23 feet, and 13 feet 6 inches in height ; they are divided by a wall, in which are the open fire- places, ventilators, &c. This wall is perforated with large circular openings, to allow a free communication for the air from window to window, which can be regulated according to the direction of the wind. The admission of cold air into buildings of this nature requires great care, as the slightest draught upon the patients would be productive of the worst consequences ; it should be distributed as much as possible over the whole room. This effect is attained by forming each window into a kind of louvre. When, open, as shown in Fig. 337, the sash is at an angle of incli- nation, cau.sing the cold air to enter above the heads of the patients, as HEATING OP NEWCASTLE INFIRMARY. 491 indicated by the arrows, no beds being placed immediately under the windows. Cold air is also admitted to the centre of the rooms at the table foot, as Fio- 337- ^^-= If \ ;|i;| i^^ifT^T^ r ^ nf 3'^ :^ .)- ^^^^^ Hh^Hl ■M^ JKM . ■! B^:::^'^^'^ HI ■"in ^ J^ i if l" IHI »■ ^ ::^ Kl -TTTf-— n err- fr -!r^"r\i ■ m n lOM so 10 2D i 338, at a sufficient distance from the The outside walls are built hollow. Fig. 338. shown upon the upper floor in Fig, beds to produce no inconvenience, having an air-vent c, 3 inches wide, communicating with the atmosphere by air-holes at the top and bottom. A current of air is thus established, which prevents the deposition of moisture on the walls. From this vent, the cold' air is conveyed by an air-channel d, formed along the ceiling by the bearers or beams which carry the floor, and admitted at the table leg, where there is a valve which can be closed at pleasure.' The contaminated air is re- moved from the several wards by exhaustion, on a very simple plan, as shown in the engraving. The fire-places are placed back to back, having a malleable iron air-cham- ber between them, protected from the action of the fire by fire-clay lining. It is perforated at the top and bottom, to allow the at- mosphere, which is supplied to it from the room below, to become heated and pass off by the ventDating flue c (the dotted lines in Fig. 337 are smoke-flues). Thus the heat of the fire in the ward above is made to ven- 492 HEATING THE HOUSES OF PARLIAMENT. tilate the one below. The uppermost ward is ventilated upon the same plan, although there is of course no fire-place above it ; the ventilating flue, receiv- ing additional heat at each story, becomes sufficiently warmed to draw the vitiated air from the uppermost. The power of the ventilating flue is increased by burning a jet of gas on either side of the iron chamber, which jets are shown in aU the ventilators. Fig. 338, and are intended not only to assist the ventilation in summer, or when the difierent fires are not burning, but also to serve for lighting the wards. Advantage is also taken of the heat of the gases from the fires of the bake-, brew-, and boiler-houses, which are conducted along insulated iron cylinders encased with brick. The gases from these cylinders are conveyed into one flue g, whjle the heated air is conveyed into the ventilating flue e. The heat generated from these flues is of course very great, and, on trial, was found to be so powerful, that the architect was enabled to make use of the superfluous warm air to supply additipn^%6at to the wards when required. • The extreme simplicity of this method, and the extraordinary ventilating power obtained, render it in every way adapted to heating or ventilating an infirmary, or large rooms where numbers of people assemble. For churches, theatres, and indeed all rooms where large numbers of persons are constantly congregated together, a thorough supply of pure, fresh, but at the same time genial air, is an object of the greatest conse- quence, although formerly it received little attention. Churches are, for the most part, filled with roasted or over-heated air, whilst the upper parts of theatres cannot be endured by persons of delicate constitution. The necessity of attending to proper ventilation is now, however, generally recognized, and numerous plans have been proposed and experiments under- taken to effect this in the most complete and economical manner. The plan adopted for the Infirmary at Newcastle is only one of many others which have been tried with variable success. The problem to be solved is the economical supply of an adequate quantity of pure and properly warmed air to a certain area in a given space of time ; the amount of air required varying of course with each individual case. It appears that hygeists are not agreed as to the mean quantity of air required by a number of individuals during a given time, and until this point is definitively settled, the calcul&,tionswhich:> must obviously be based upon it will necessarily differ according to the, standard assumed by each " observer. There can be no doubt, however, that it is preferable to have a supply of fresh air in excess of what is required rather than a deficiency, although the latter has fre- quently been the practice. In the former House of Commons, which was warmed and ventilated under the superintendence and according to the plans of Dr. Heed,* the air was supplied from Old Palace Yard to the basement of the building. Passing first through a fibrous veil 42 iFeet long by 18 feet 6 inches deep for the ex- clusion of visible soot, the air arrived at the heating apparatus, consisting of large chambers intersected by steam pipes, and proceeded from thence to other chambers, where it was mixed with cold air and brought to any required temperature. The floor of the house was double, and the space below the floor could be connected by means of valves with the hot-air chamber. The floor was perforated by a great number of apertures, and these were covered with hair-cloth, so that the hot air in escaping from the floor into the body of the house was well diffused, and no perceptible current was expeiienced. Having performed its functions, the vitiated air ascended to the ceiling, which was also double and perforated, in the same manner as the floor, whence it was carried off" by the draught created by a powerful fire under • Author of the " Theory and Practice of Ventilation." THE HOUSE OF LORDS.— VITJATION OF AIR. 493 a chimney shaft erected in another part of the building. In the present House of Commons, there seems to have been no plan followed, and, con- sequently, there is great confusion about the heating arrangements. (See Dr. Percy's report.) The pkri adopted by Mr. Barry for warming and ventilating the House of Peers, the royal ante-chamber, and the public lobby, differs from that just described both as respects the admission of the air and its removal. The floors of the rooms are not perforated, and are heated in the first instance simply by the passage of hot air below them ; the hot air then escapes by passages along the external sides of the rooms to the ceiling, which is divided into two compartments, the one for the admission of the warm air, entering at the sides, and the other for the exit of the vitiated air. The warm air after passing below the floor to the roof becomes somewhat cooled, so that its temperature on entering the ceiling is a few degrees lower than that actually present in the room ; it consequently descends to the level at which it is at once heated again, and, deteriorated by combustion, respiration, &c., rises through the centre of the room, passing through the ceiling to a foul-air chamber above, whence it is conducted to a chimney and carried off by the peculiar motive power first suggested by Dr. Richardson for the pro- duction of draught. This power consists of a jet of steam, which, when produced under pressure of 32 lbs. to the square inch, is capable of setting 217 times its bulk of air in motion ; 10,000 cubic feet of air are thus gra- dually diffused through the three apartments per minute, no draught of any kind is perceptible, and no inconvenience is experienced from dust or other solid particles being carried mechanically forward by the air, as is said to be the case when the air enters from the floor. In other large buildings, as at the prison in Millbank, warm air is admitted at the ceiling, and carried off by the draught of a chimney in connection with the sides or lower part of the rooms. At the Reform Club, and at the Hospital for Consumptive Patients at Brompton, warm or cold air is forced forward by a fan or pumped by a steam-engine in the basement, into channels which convey it over the whole building ; being subsequently allowed to escape through the chimneys and other apertures. Although it is not probable that the same arrangements can be adopted for heating and ventilating all extensive buildings, differing in construction and in the uses to which they are applied, yet it is to be hoped that the various experiments which have been tried upon a large scale may lead to a sound knowledge of the fundamental principles to be observed for securing an object so conducive to health and comfort.* The extent to which the air is vitiated by respiration, transpiration, and the combustion of illuminating materials is estimated by P6clet as follows : The respiration of an individual has been ascertained to vitiate nearly 12 cubic feet of air per hour. The water exhaled by the lungs and skin amounts to 589 grains (0.084 lb.) in the same time ; and supposing the air to be at a temperature of 59° F., and to take up about half of the quantity of moisture it is capable of sustaining at that temperature, which is about the average quantity it does take up, there will be required in round numbers per individual per hour, 212 cubic feet of air, to remove all the exhalations from the skin and lungs. The substances employed for giving light require oxygen from the air in proportion to the amount consumed, and if ^ of the oxygen contained in the * Examples of Gen. Moiin's system, and of large halls, churches, and theatres in England successfully wanned and ventilated on Mr. Constantine's plan, are given in the book of the latter on "Practical Ventilation. and Warming" (London : Churchill). See also Box, " Practi- cal Treatise on Heat " (London : Spon). 494 APPLICATION OF FUEL TO VAPOEIZATION. air be the quantity abstracted by the combustion, candles of 6 to the lb. will each require about lo cubic feet, wax candles about the same quantity, and oil or lamps with large burners about 40 cubic feet per hour. The quantity of carbon consumed in the process of respiration amounts to about 155 grains per hour, and this, calculated on the principles already referred to, would afford 73 units of heat ; but a large portion of this heat is required to retain, in a state of vapour, the moisture exhaled — amounting, as stated above, to 589 grains — and is not available as sensible heat : the quantity is thus reduced to 48 units of heat, which would be in itself sufficient to heat the amount of air required for respiration to a proper temperature, if the heat so communicated were not dissipated by trans- mission through the walls and windows of dwellings. The loss of heat from these sources has been estimated for a diflference of temperature of 36° F. between the external and internal air, and an intermittent system of heat- ing, at about 7 units of heat per hour per square foot, for walls of i foot thickness, and at about 8 units for every square foot of glass window surface. From these data, an approximate estimate may be made of the amount of air to be supplied in each case of practical application, and of the amount of heat required to be communicated to it under different cir- cumstances. Professor Thomson has thrown out the idea that air may be heated for warming and ventilating dwellings by mechanical agency solely, as by a water-wheel or with the aid of a less quantity of fuel in a steam-engine, than could be made to produce the same amount of heat in a direct manner. On the general principles of the dynamical theory of heat, he states that " it is mathematically demonstrable, that any substance maybe heated 30° (Fahr.) above the atmospheric temperature by means of a properly contrived machine driven by an agent spending not more than -^-g of energy of the heat communicated ; and that a corresponding machine, or the same machine worked backwards, may be employed to produce cooling effects requiring about the same expenditure of energy in working it to cool the same sub- stance through a similar range of temperature. When a body is heated by such means about f yths of the heat is drawn from surrounding objects, and ^\th is created by the action of the agent ; and when a body is cooled by the corresponding process, the whole heat abstracted from it, together with a qi(antity created by the agent, equal to about ^'^th of this amount, is given out. to the surrounding objects." As no such method of heating air has yet been- practically employed, we must refer the reader, for the theoretical details on this very interesting topic, to the author's paper in the Phil. Mag. for February 1854. Application of Fuel to Vaporization. — Fuel is used very extensively for the conversion of liquids into vapour. For this purpose, the heat pro- duced by the combustion of the fuel is communicated to the Uquid, through the medium of a metallic vessel, or sometimes the current of heated gases is carried rapidly over the surface of the liquid to be vaporized In the first, the material of the vessel and its thickness affect the trans- mission of the heat, but not to a degree which practically interferes with work at the temperatures ordinarily employed in the arts. The quantity of heat which can be passed through the metal of boilers or similar vessels in a given time is, however, an amount which can be measured, as it is within the range of well-defined laws and is not an arbitrary or doubtful matter. Metals possessing different degrees of conductivity are used in the construction of vessels which hold liquids whose thermal con- ductivity and viscosity also range between limits more or less large, and the processes used in heating these vessels, and the temperature to which they are submitted (or to which it may be desired to submit them) are materially LAWS OF TEANSMISSION OF HEAT. 495 diverse, so that, with such varying elements, it becomes useful to have the means of learning what result may be expected. The subject has been investigated principally by Peclet,* Wiedmann and FrauZjt Clerk Maxwell, Angstrom, and Prof. Tait, and has been expressed somewhat differently by each. Clerk Maxwell J proposed the following formula : — H = — (T-S) where ah = area of plate c = thickness of plate t = time k = specific thermal conductivity of material H = whole heat conducted in time t T - S = the difierence of temperature which causes the flow. That is to say, the flow of heat in a given time is a constant quantity, and is proportional to the area and to the diSerence of the temperatures at the two surfaces, and inversely to the distance between them, or the thickness of the metal. As determined by Angstrom, as much heat will pass, in one minute, through each square centimetre of plate iron, i centimetre thick, as will suffice to raise i gram of water through 9. "77 C, the diiference of tempera- ture between the iron and source of heat being 1° C, and the temperature of the iron about 51° C. Thus, if the tempei'ature of water and iron in a boiler were 51° C, and the temperature of a flame striking the boiler surfaces were 1000° C, the amount of heat passing through i square centimetre of the plate, supposing it to be I centimetre thick, would be „ „iooo - !;i„ Q = 9.77xS ^T where Q = quantity of heat in gram centigrade units S = area in square centimetres e = thickness of plate in centimetres T = time in passing. Assuming one minute as the time, we have Q = 9-77 X (iooo-5i) = 927i-73; that is, in one minute, the temperature of the furnace being 1000° and the water 51°, there would pass through a square centimetre of boiler plate 1 centimetre thick, as much heat as would raise 9271.73 grams of water through 1° C.§ Some very interesting practical limitations to the strict application of \ these laws in the case of steam boilers have been pointed out by Mr. W. Anderson, who investigated the thermo-dynamic questions connected with the generation of steam || from the point of view that, as he expressed it, "A steam pumping-engine which furnishes water under high pressure to raise loads by means of hydraulic cranes, is not more truly a heat-engine than is a simple boiler, for the latter converts the latent energy of fuel into the latent energy of steam just as the pumping-engine converts the latent energy of steam into the latent energy of the pumped-up accumulator or the hoisted weight." In this view, he applied to the steam boiler the general " TraM de la Chaleur. T PoB9- Ann., Ixxxix. p. 497. } " Theory of Heat," chap, xviii. § See On the Design and Use of Steam Boilers, by F. J. Eowan : " Brit. Assoc. Eeports," 1878 i " Engineering," vol. xxvi. pp. 164, 283. II On the Generation of Steam and the Thermo-dynamic Problems Involved : Inst. C.E, lectures on " Heat in its Mechanical Applications," 1883-4. 496 APPLICATION OF CAENOT'S LAW TO BOILEES.' principle announced by Sadi Camot in 1824 — viz. : " That the proportion of work which can be obtained out of any substance working between two temperatures depends entirely and solely upon the difference between the temperatures at the beginning and end of the operation — that is to say, if T be the higher temperature at the beginning, and * the lower temperature at the end of the action, then the maximum possible work to be got but of the substance will be a function of (T—t). The greatest range of temperature possible or conceivable is from the absolute temperature of the substance at the commencement of the operation down to absolute zero of temperature, and the fraction of this which can be utilized is the ratio which the range of temperature through which the substance is working bears to the absolute temperature at the commencement of the action. If W = the greatest amount of effect to be expected, T and t = the absolute temperatures, and H = the total quantity of heat (expressed in foot-pounds or in water evapo- rated, as the case may be) potential in the substance at the higher tempera- ture T at the beginning of the operation, then Camot's law is expressed by the equation : — W = H Ct}" In order to show the application of this law to the case of a steam boiler, Mr. Anderson supposes that the fuel used is pure carbon, such as coke or charcoal, the heat of combustion of which he takes at 14,544 units, that the specific heat of air and of the products of combustion at constant pressure is 0.238, that only the quantity of air theoretically requisite to supply oxygen for the combustion of the carbon is employed, and that the temperature of the air is 60° F. or 520° absolute. T, then, represents the absolute temperature of the furnace, which he calculates as follows : — " I lb. of carbon requires 2§ lbs. oxygen to convert it into carbonic acid, and this quantity is furnished by 12.2 lbs. of air, the result being 13.2 lbs. of gases, heated by 14,544 units of heat due to the energy of combustion; therefore : — „ „ 14,^44 units „ , , T= 530°+ —^^^^ 5= 5-150 absolute. •''' 13.2 lbs. X 0.238 •' -^ The lower temperature, t, we may take as that of the feed water, say at 100" or 560° absolute," and supposing the waste gases reduced by artificial means to that temperature, then the proportion of heat which can be realized is : — 5150° -560° = z = 0.80 1 : 515° ^ ' " that is to say,'' remarks Mr. Anderson, " under the extremely favourable, if not impracticable, conditions assumed, there must be a loss of 11 per cent." In investigating the numerical value of H, which is the potential energy to be derived from i lb. of carbon, the specific heat of carbon being 0.25, and the absolute temperature of air 520°, the following figures are used: — Units. I lb. of carbon x 0.25 x 520 . . = 130 12.2 lbs. of air X 0.238 X 520 ... = 1,485 Heat of combustion . . . . . . = 14,544 16,159 Deduct heat-equivalent to work of displacing atmosphere by pro- ducts of combustion raised from 60° to lco°, or from 149.8 cubic feet to 161. 3 cubic feet . . . . . , 32 Total units of heat available . . . . 16,127 ANALYSIS OF BOILEK PEEFOKMANCE. 497 Equal to 16.69 ^^^- °^ water evaporated from and at 212° F. Hence the greatest possible evaporation from and at 212° from i lb. of carbon is W = 16,159x0.891-32 966 units = 14.87 lbs. Mr. Anderson has shown the application of this method of calculation to the specific case of the results of trials with an 8-horse portable engine boiler at Cardiff, which " were carried out with great care and skill by ■Sir Frederick Bramwell and the late Mr. Menelaus," in 1872, and are recorded in voL ix. of the Journal of the Eoyal Agricultural Society.* The temperature of the furnace was not determined, on account of the absence of a trustworthy pyrometer, but the other data observed were as follows : — Steam pressure 80 lbs.. Temperature Mean temperature of smoke Temperature of the air „ „ feed water Water evaporated per i lb. coal, from and at 2 1 2° . Heating surface . Grate „ . . . . Coal burnt per hour .... 324° = 784° absolute 389° = 849° 60° = 520° 209° = 669° ,, = 11.83 lbs. 220 square feet 3-29 41 lbs. " The fuel used was a smokeless Welsh coal, from the Llangennech Collieries. It was analysed by Mr. Snelus, then of the Dowlais Ironworks, and in the following Table are shown the details of its composition, and the weight and volume of air required for its combustion : — PROPERTIES OF LLANGENNECH COAL. Analysis of I lb. of Coal. Oxysren required for Com- bustion. Pounds. Products of C'imbus. tion at 32° F. Cubic Feet. Volume Per Cent. Carbon ... ... Hydrogen . ... Oxygen . Sulphur . . Nitrogen ... . . Ash. . . Total 9j lbs. nitrogen 6 lbs. excess of air . . . ■ . Total cubic feet of products per i lb. coal . 0.8497 0.0426 0.0350 0.0042 0.0145 0.0540 2.266 0.309 2530 7.60 o.iS 1 18. go 74.40 II. I 3-4 \ ) 85. 5 1. 0000 2.572 — — 226.40 lOO.O The total heat of combustion in lbs. of water evaporated — = 15.0610.8497 + 4.265(0.426 --^-g—)| - 15.24 lbs. of water from and at 212" = 14.1727 units of heat. "The temperature of the furnace not having been determined must be calculated on the supposition that 50 per cent, more air was admitted " See also " Min. Proc. Inst. C.E.," vol. lii. p. 154. K K 498 ANALYSIS AND INDICATOR DIAGRAM FOR BOILERS. than was theoretically necessary to supply the oxygen required for perfect combustion. This makes i8 lbs. of air per i lb. of coal, consequently 19 lbs. of gases would be heated by 14,727 units of heat. Hence — T = 14,727 19 lbs. X 0.238 ^ 5' above the temperature of the air, or 3777° absolute. The temperature of the smoke, t, was 849° absolute, hence the maximum duty would be — 3777°-849° _ 3777° -°-"S2- " The specific heat of coal is very nearly that of the gases at constant pressure, and may, without sensible error, be taken as such. The potential energy of i lb. of coal therefore, with reference to the oxygen with which it will combine, and calculated from absolute zero, is — Units. 19 lbs. of coal and air at the temperature of the air contjiined 19 lbs. X 520° X 0.238 2,350 Heat of combustioD ......... 14.727 Deduct heat ejcpended in displacing atmosphere, 151 cubic feet Total potential energy Hence, work to be expected from the boiler — 17,078 422 16,656 17,078 units X I / 3777° - 849° \ 3777 1 — 422 units 966 units = '3-27 lbs. of water evaporated from and at 212°, corre.sponding with 12,819 units. The actual result obtained was 11.83 lbs. j hence the efficiency of this boiler was — ^ = 0.892." 13.27 y In order to illustrate fully his view of the action of a boiler as a heat Fig. 339. Seadng Stirfiut'230 sf ff »i engine, Mr. Anderson proposed the ingenious " indicator diagram," shown in Fig. 339. EXAMINATION OF COMBaSTION TEMPEEATUEES. 499 Regarding the nature of this diagram, we have the following remarks : — " The rate of transfer of heat from the furnace to the water in the boiler, at any given point, is in some way proportional to the difference of tempera- ture, and the quantity of heat in the gases is proportional to their tem- peratures. " Draw a base line representing — 460° F., the absolute zero-of tempera- ture. At one end erect an ordinate upon which set oiFT = 3777°, the temperature of the furnace. At 849° = t on the scale of temperature, draw a line parallel to the base, and mark on it a length proportional to the heating surface of the boiler ; join T by a diagonal with the extremity of this line and drop a perpendicular to the zero line. The temperature of the water in the boiler being uniform, the ordinates bounded by the sloping line, and by the line t, will at any point be approximately proportional to the rate of transmission of heat and the shaded area above t (in Fig. 339), will be proportional to the quantity of heat imparted to the water. Join T by another diagonal with the extremity of the heating surface on the zero line, then the larger triangle, standing on the zero line, will represent the whole of the heat of combustion, and the ratio of the two triangles will T — < be as the lengths of their respective basis, that is, as -7?;— which is the expression we have already used. "The heating surface was 220 square feet, and it was competent to transmit the energy developed by 41 lbs. of coal consumed per hour = 12,819 u. X 41 = 525,572 units, equal to an average of 2,389 units per square foot per hour ; this value will correspond to the mean pressure in an ordinary steam-engine diagram, for it is a measure of the energy with which mole- cular motion is transferred from the heated gases to the boiler plate and so to the water. The mean rate of transmission, multiplied by the area of heating surface gives the area of the shaded .portion of the figure which is the total work which should have been done, that is to say, the work of evaporating 544 lbs. of water per hour. The actual work done, however, was only 485 lbs." " The great enemy to attaining a high temperature in the furnaces is the quantity of air required to ensure perfect combustion. "We have seen that 12.2 lbs. of air are sufficient for the complete combustion of 1 lb. of carbon which will then develop sufficient energy to raise the temperature of the products of combustion to 5150° absolute. In practice, however, a con- siderable excess of air has to be used, and the energy developed, which is not increased by the excess of air, is expended in heating a greater weight of gases and consequently the temperature is lowered. Fig. 339 exhibits this effect by means of a curve which indicates the temperature of a furnace with from 12.2 lbs. to 36.6 lbs. of air per lb. of carbon. " Unfortunately no pyrometer exists by means of which the temperature of furnaces can be readily ascertained, but the melting-points of steel have been determined with some accuracy. The late Sir W. Siemens said that cast steel with i per cent, of carbon melts at 3192° absolute, whilst steel boiler plates melt between 3462° absolute and 3552° absolute and that the latter is very nearly the melting-point of platinum. On Fig. 339, lines parallel to the base, indicating the extreme temperatures of melting steel, intersect the curve of furnace temperature. To melt boiler plates, the quantity of air admitted should thus not exceed i ^ times the theoretical quantity, and even for cast steel it must not exceed if times." " The practical difficulty connected with raising the temperature of the furnace lies in the limited power of boiler plates to stand the high tempera- ture, especifl,lly with hard water. With temperatures a little above that of melting steel, there does not appear to be any trouble when the water is soft, K K 2 Soo CUEVES OF COMBUSTION TEMPEEATURES. but at higher ranges boilers wear very fast, as, for example, when petroieum is used. This substance is composed of about 0.84 of carbon and 0.16 of hydrogen ; i lb. of the oil only requires 10.32 lbs. of air for its combustion and yields 22.136 units of heat. The temperature of the furnace therefore with only sufficient air to ensure perfect combustion is 8216° absolute, and the curve on Fig. 340 shows that to bring the temperature down to that of Fio. 340. an ordinary furnace would require the use of 2| times the proper quantity of air." " The temperature t of the products of combustion cannot be lowered below the temperature of the feed water. In condensing engines this is about 100°, but without enormously extending the heating surface this point cannot be attained, and the temperature of the chimney must be kept at least 100° higher, or at 200°. In the Cardiff engine, the smoke tempera- ture was only about 65° higher than that of "the steam, and if by means of feed heaters in the flue the temperature of the smoke could be reduced to 165°, then with 18 lbs. of air to the pound of coal the fall of temperature from 389° - 165° = 224°, would yield 19 lbs. x 224° x 0.238= i. 013 units, competent to raise 11.83 lbs. of feed evaporated per lb. of coal 85.6° or to a temperature of 185.6°, which would still be 103° short of the temperature of the boiler." " In practice the chimney temperature cannot be lowered to the point indicated unless forced draught be employed, but independently of the advantage gained by improved duty due to the higher temperature of the furnace, there is positive gain if moderate blast-pressure be used. In the experiments made with H.M.S. Satellite and Conqueror in 1882, it was found that \ inch of air-pressure in the stoke-hold produced the same result as the ordinary chimney draught, that ^ inch pressure corresponded with the TRANSFER OF HEAT THROUGH BOILER PLATES. SOI steam-blast in the chimney, and that i inch of pressure was sufficient to ensure about 38 per cent, additional steam, but at a sacrifice of efficiency on account of the boilers being forced beyond their heat-absorbing power. 18 lbs. of air at 60° measure 236 cubic feet, and if forced in under an inch of water-pressure would absorb 1,224 foot lbs. of work, or assuming 50 per cent, duty, 2,447 indicated foot lbs. per i lb. of coal consumed. An engine burning 5 lbs. of coal per I.H.P. per hour would absorb 91 units of heat in doing this work ; but the heat abstracted from the smoke by lowering its temperature is 1,013 units, hence the power necessary to produce forced draught is only about jV^h of that gained by cooling the smoke down to 165". The necessity, in any case, of building chimneys to carry off the .smoke has no doubt deterred nearly every one from trying forced draught, not as a means of temporarily increasing the boiler power, as in the torpedo boats and larger war-ships, but as the proper and rational way of exalting the duty obtained from fuel — namely, by raising the temperature of the furnace and lowering that of the smoke to the utmost extent possible, in accordance with Carnot's theory." The sources of loss ia the practical work of generating steam are, accord- ing to Anderson, first, loss by radiation from the furnace to the ash-pit and furnace-door and by radiation and convection from the body of the boiler ; second, an indefinite loss, arising from imperfect combustion ; and third, loss in the transfer of heat from the heated fuel and gases, first to the boiler plates and then to the water. " In the furnace, the radiation from the incandescent fuel is very intense, and most of the heat is transferred to the boiler-plates by this agency, because very few points of the fuel are in actual contact with the plates and therefore are not in a condition to transmit by conduction. Iron and copper are probably only slightly diathermanous — that is to say, at the thicknesses which occur in practice a very small pro- portion of radiant heat passes directly through the plate." " All energy transferred by undulatory movement, whether heat, light or sound, suffers absorption or reflection in passing from one medium to another ; thus, in passing through the clearest glass, a ray of light emerges shorn of some of its brilliancy, a part being reflected and a part absorbed. The rays of heat, in like manner, are arrested to a varying extent, depending on the nature of the substance, in part reflected, in part absorbed ; and Prof. Tyndall's experiments on fog signals at the South Foreland show that sound is in like manner affected when passing through media of varying density. " The rate of transfer of heat through a plate varies directly as its thick- ness, directly as the difference of temperature on its two sides, and probably inversely as its absolute temperature ; but, unfortunately, it is impossible to ascertain what the actual temperature of either side of a boiler-plate is. It is quite certain that the side of the plate next the furnace is very greatly below the temperature of the fuel and the flame, because, if it were not, copper furnaces and brass tubes, which melt below 2000°, would very soon be fused ; and, on the other hand, on the water side, we have no means of telling how much hotter the plate is than the water. It is evident that the greater part of the radiation from the fuel must be reflected backwards and Forwards, keeping up the temperature of the gases, which part with their heat-energy by degrees as they pass along the flues. " A certain amount of heat-energy passing through a boiler-plate is lost in keeping up the molecular motion of an imperfectly elastic material. It may be likened to the flow of water through a pipe inclined so as to be ' in train,' that is, till the rate of inclination exactly equals the retarding force of friction. The longer the pipe the greater amount of heat will disappear in overcoming friction, and so the thicker the boiler-plate the greater difference S02 BATE OF HEAT TRANSMISSION IN BOILEES. there will be in the temperature of its two sides, and the greater loss of heat in the passage of a given quantity. " Again, at the surface, where the heated gases touch the plates, and where the plates touch the water, there is a change of density and of material, and consequently a certain amount of loss arises. We do not know sufficient of the nature of heat -motion to say what takes place in its transfer by conduction from one body to another ; but it is certain that wherever there is a joint, even in a bar of uniform material, there a certain amount of resistance and loss arises." " In the indicator diagram (Fig. 339), we have assumed that the rate of transmission of heat from the gases to the water is in direct proportion to the difference of temperature, but this is probably not strictly correct, because the conductivity of substances varies inversely as the temperature, probably as the absolute temperature ; hence the rate of transfer of heat at the furnace end will be slower in proportion than at the chimney end, but to what extent it is impossible to say, because the mean temperature of the boiler-plates is unknown. It is certain, however, that it is below even the melting-point of lead, or 630° F., because lead safety-plugs are frequently used, even in locomotives, and they do not melt out unless there be a want of water. If we assume the mean temperature of the plates at the furnace end to be 500°, and that of the chimney end 350°, then the rate of trans- mission at the cooler end will be about 18 per cent, greater than at the hotter. Were it not for the imperfect absorption of radiant heat and reduced conductivity, caused by high temperature, ebullition over and about the furnace would be so violent that uncontrollable priming would surely take place." " The rate of transmission of heat by the heating surface of a boiler can thus be approximately calculated. In the case of the Cardiff boiler, the combustion of 41 lbs. of coal per hour was capable of yielding 525,572 units of heat. The mean temperature of the gases was estimated at 2313° abso- lute, that of the water in the boiler 784°; hence, the mean difference of temperature was 1529°. The heating-surface being 220 square feet, U, the number of units of heat absorbed per square foot per difference of 1° per hour would be — U= 5^35.572 units ^ ^^j^_ 1529 X 220 square feet " In this ease, glowing fuel and heated gases impart, chiefly by radiation and convection, their energy to water at a lower temperature. The action is the inverse of that which takes place where hot water or steam is used for heating buildings ; we might expect, therefore, according to the doctrine of exchanges, that the work done per unit of surface and difference of tem- perature would be approximately the same. In vol. xviii., Min. Proc. Inst. C.E., will be found a curve from which the units of heat given out by a 2 -inch wrought iron hot- water pipe may be ascertained. For a difference of 190° between the temperature of the water and the air being heated, 590° units per square foot per hour were given out; this is equal to 3.1 units per square foot per difference of 1° per hour, or about double the amount realized at the Cardiff trials. This is accounted for partly by the fact that the plates and tubes of the boiler of the portable engine were, on the whole, thicker tha^o the metal of the heating-pipes, partly by the con- ducting power of the surfaces having been reduced in consequence of their high temperature, but chiefly by the circumstance that the temperature of the furnace-plates, for a considerable portion of the smoke-run, is very much less than that of the glowing fuel and gases, hence the mean temperature of VELOCITY OF HOT GASES — VAPOKIZATION. 503 the plates would be considerably lower than that of the products of com- bustion. " Until a trustworthy pyrometer is found, it will be impossible to deter- mine more accurately the rate of transmission, but it may be stated that in practice 1 2 square feet of flue-heating surface, measuring only the half over the gases, or 10 square feet of small tube surface, measured in the same way, will transmit the heat necessary to evaporate i cubic foot of water per hour from and at 212°. The French allow i square metre or 10.76 square feet per horse-power, but the value of a French boiler horse-power has not been accurately defined." Regarding the question of velocity of gases through flues and tubes, constituting the heating surface of boilers', Mr. Anderson states that " from a number of boilers in actual work with chimneys of moderate height," he had "deduced that for a temperature of 400°, a velocity of 1 0.8 feet per second is admissible ; this corresponds to 10 square inches of flue section per boiler horse-power (which he defines as i cubic foot of water evaporated from and at 212°), and for a consumption of i lb. of coal to 10 lbs. of water converted into steam." Various methods are adopted in converting hquids into vapour accord- ing to the object in view, although the manner of applying the fuel differs but little in principle. 1. Vapour is produced for its motive power and as a carrier of heat, and the operation may then be distinguished as Vaporization. 2. The object may be to separate by vaporization and collect by con- densation, a more volatile from a less volatile liquid, and the process is then called Distillation. 3. The simple removal of a volatile liquid from a substance which is •ess volatile or fixed is called Evaporation. 4. When the liquid that moistens a solid is removed by evaporation, the process is called Desiccation or Drying. Vaporization. — It is beyond the limits of the present work to enter on a description of the form, dimensions, thickness, or other particulars con- nected with the boUers employed for the purposes of raising steam of difierent degrees of pressure ; and we therefore confine ourselves to a few illustrations of the usual and approved arrangements adopted for applying the fuel required to raise steam. The furnace is placed in the case of cylindrical and oval boilers either below the boiler or in a flue or cylinders within it, so as to be completely surrounded by the surface containing the liquid, and the hot gases are con- ducted to the chimney by a flue or series of flues, which are brought more or less into contact with the external surface of the boiler, so as to be cooled down to a temperature of about (300° C.) 550° to 600° F., which corresponds with the maximum amount of draught in the chimney. In the locomotive boiler, the barrel of which is cylindrical and contains a number of tubes act- ing as flues for the hot gases, there is a fire-box buUt at one end, which is usually of rectangular shape. Water-tube boilers present a different case, and are of such a variety of forms that plans are requisite in describing them. The grate is generally constructed of wedge-shaped bars of cast-iron, the broad part of the wedge being placed uppermost. The extent of grate-surface is regulated by the amount of work to be done, the size of the boiler, and the kind of fuel to be employed. The usual dimensions, when coal is used as fuel, are i square foot of grate-surface for a consumption of about 20 lbs. of coal per hour. Tredgold recommended about a square foot of grate-surface for every horse-power of vapour required, which, estimating the coal con- sumed at 1 1 lbs. per horse-power (not an unusual rate in early days), would have very much increased the size of the grate. 504 RELATIONS OF GRATE SURFACE AND FUEL CONSUMPTION. The following relations between fuel consumed, grate-surface, and heat- ing-surface were given by Mr. Prideaux in an admirable little work on the economy of fuel, in which he advocated the use of compressed air to in- crease the heat of furnaces : — ■ Fuel burnt per hour per square foot of fire-grate : In Cornish boilers . . . . . 3j to 4 lbs. In factory and marine boilers . . . 10 to 16 „ In locomotive boilers . . . . 80 to 100 „ The number of square feet of heating-surface in boiler required to evaporate i cubic foot of water per hour is : In Cornish boilers . . . . . . 70 sq. ft. In factory and marine boilers . . . 9 to 1 1 „ In locomotives . . . . . . 6 „ The number of square 'feet of heating surface to each square foot of fire- grate is : * In Cornish boilers . . . . . . 40 sq. ft. In factory and marine boilers . . . 13 to 15 „ In locomotives . . . . . 50 to 70 „ The following proportions of various forms of land boilers were given by Mr. R. B. Longridge in a paper on the " Relative Economy and Durability of Various Classes of Stationary Steam Boilers" (" Proceedings Inst. Mech. Engineers," vol. for 1859) : — A. Cylindrical boiler with 2 flues B. „ „ „ 2 ^- „ „ „ 2 D 5 E. Multiflued „ ,,7 F. Galloway , 0. „ H. „ multitubular boiler 1. Multitubular boiler . The rate of consumption of slack coal in these boilers is given in the following table in lbs. per square foot of grate-surface per hour : — A. B. C. D. E. F. G. H. I. 1st expt. . 18.1 20.5 II. 8 20.4 12.9 17.1 23.8 11.9 15.0 2ih1 „ — — 9.1 21.8 — — 23.2 92 15.6 3rJ „ __________ 15.4 Mr. Robt. Wilson (in " A Treatise on Steam Boilers ") gives the following as the average rates of combustion in various boilers using semi-bituminous coal. Similar figures are given in Rankine's " Steam-engine and other Prime Movers." lbs. per Bq. foot of Grate per Hour. Lowest rate of combustion in Cornish boilers ..... 4 Usual „ „ „ ..... 10 ,, ,, in externally fired and internally fired factory boilers . 10 to 18 „ ,, in marine boilers .... ... 14 to 26 „ „ in locomotive boilers with blast pipe . . . . . 60 to 130 The rate of combustion varies with different classes of fuel in different localities, but with solid fuel is practically governed by the chimney draught and the combustibility of the fuel.f The maximum rate of combustion of semi-bituminous steam coal with * See also "Fuel, its Combustion and Economy," pp. 206, 207, Weale's series; D. K. Clark's " Manual of Bules, Tables, and Data for Mechanical Engineers," 3rd edition, pp. 768-821. f See E. Wilson, " A Treatise on Steam Boilers," p. 272. Area of Fire- ^rate. Heating-surface. 38 sq. ft. 590 sq. fit. 35 ,- S40 „ 30 „ 463 „ 30 „ 530 ,. 52 697 „ 30 „ 499 ,. 384 „ 898 „ 30 ,. 599 .. 30 ,. 454 ,. GENERAL PEINCIPLES OF COMBUSTION IN BOILERS. 505 air-admission through the grate and above the fire, and with chimney draught, is about 40 lbs. per square foot of grate-surface per hour, but the evaporative economy* decreases rapidly with a combustion exceeding 30 lbs. The maximum rate of combustion of semi-bituminous steam coal with air- admission through the grate only is about 35 lbs., but even below this rate the intense heat given out by these coals has been found to fuse the bars rapidly. Their evaporative economy decreases with a more rapid rate of combustion than 26 lbs. These remarks apply to combustion in furnaces the air-supply to which, as well as the rate of travel of the hot gases over the heating- surface, is governed by chimney draught. The use of mechanical means for supplying the air for combustion enables higher rates of combustion to be usefully employed as the rate of escape of the hot gases is under control. This system has not yet been applied in practice in a complete form, but appi'oximations ■(• to it have been made in several instances, which have shown the economy which is possible by such means. The boiler-surfaces should be placed at some distance from the surface of fuel on the grate. If placed too near, as is very frequently the case, the flame may be extinguished, or much smoke and imperfect combustion pro- duced by the cooling effect of the boiler and its contents, which are always at a temperature greatly below that of the flame. A distance of 14 to 16 inches between the grate and the bottom of the boiler has been considered sufficient when coal is the fuel, 30 inches for wood, 20 for turf, and 24 for coke, but in most cases they may probably be increased with advantage to ensure complete combustion of the gases before they come into contact with the surfaces to be heated. With gas firing, a height of 22 to 24 inches has been found by experiment to be the most suitable for the combustion chamber. The advantage of fines in bringing the heated gases into contact with the sides of the boiler was disputed by many engineers for a considerable time, and the whole value of the fuel was attributed to the radiant heat it afforded ; but this erroneous view has long since been disproved, and arose from the fact of far too large a quantity of air being admitted to the fuel, which cooled the products of combustion to such an extent as to render them nearly valueless as a source of heat. With a view to test this opinion in a practical manner, a commission of the Industrial Society of the Grand Duchy of Hesse experimented on the relative efTect produced by a different arrangement of the furnace and fiues in relation to the boiler, with different kinds of fuel, the same boiler being employed in all the experiments, although the furnace was differently arranged in each case. The following were the arrangements tried ; — A. No flues were constructed, but the boiler was freely suspended above the fire. B. The bottom of the boiler was alone exposed to the radiant heat of the fire, and the heated gases circulated once round the boiler in a flue which commanded the entire height of the sides of the boiler. C. The bottom of the boiler was expo.sed to the radiant heat, but the heated air circulated twice round the sides of the boiler, the fine being only one-half as high as in experiment B. B. The fire was arched over, leaving an aperture in the centre of the arch, through which the hot gases impinged upon the bottom of the * For methods of calculating efficiency of furnaces, see Rankine, " Steam Engine and other Prime Movers;" T. Box, "Practical Treatise on Heat," &c. t See 0. Wye Williams, " Fuel, its Combustion and Economy ; " Bankine, " Steam Engine &c.;" J. F. Flannery, "Proc. Inst. N.A. ;" J. Howden, "Proc. Inst. N.A." So6 CORNISH BOILERS. boiler, and circulated freely and simultaneously round the sides in an annular space before escaping to the chimney through several apertures at the sides. E. The bottom of the boiler was heated by direct radiation, and the heated air traversed the sides of the boiler in two flues, one on either side, which joined again above the fire, and each of which was consequently only the half of the circumference of the boiler in length. F. The bottom was heated by radiation, and the hot gases traversed simultaneously two flues placed on either side, each making the complete circuit of the boiler. The following table contains the results of the experiments ; the figures indicating the quantities of fuel employed for producing a similar effect in the same space of time ; the highest corresponding with the most defective plan : — { F. E. a B. D. A. ' { 63 68.8 68.9 72.19 7223 100 Wood F. 0. D. E. B. A. Si 66 71 72 76 100 0. F. B. F. D. A. 73 73 83 85 91 100 Turf. Coal. The result of these experiments clearly shows, in the first place, the advantage of allowing the hot gases to circulate in flues round the boiler ; secondly, that, with suitable flues, the saving of fuel is much greater when turf and wood are employed than is the case with coal ; in the case of turf, nearly the same effect being produced with | the quantity, ^rd being saved in the case of wood, and ^th only in that of coal. It appears, moreover, that two flues are more effective than one, and the arrangements indicated in experiments E and F are generally the most beneflcial. The arrange- ment adopted in experiment D does not appear to have had a fair trial. If the arch were employed in con- FiG. 341. junction with a system of flues, it is probable the efiect would have been greatly increased. Coal .radiates much more heat than either wood or turf, but, any great depth of fuel not being adapted to the consump- tion of coal, a much larger quantity of air generally passes through the grate and furnace than is required for its com- plete combustion, and this of course tends to diminish the temperature of the gaseous products, and accounts for the diminished action of the flues. The arrangement of the fur- nace which is generally adopted in this country, and considered the most economical, is that in which the furnace is surrounded by the boiler, as shown in Fig. 341. This is the con- struction adopted in the large boilers employed at the Cornish mines, which are celebrated for the large amount of work performed at a small cost of fuel. The outer cylinder is of very large dimensions, being often 6 feet in diameter and 60 feet long. The hot gases, after passing through the centre of the boiler, return through the flues o before escaping to the chimney. These LOCOMOTIVE BOILERS. 5°? boUers are often worked at a pressure of 75 lbs. to the inch and upwards. The grate is large in proportion to the consumption of fuel, as well as the 5o8 MARINE BOILERS. heating-surface, so that the gases escape to the chimney at a temperature only just suflB.cient to maintain a draught. In marine engines and locomotives, where space must be economized and high chimneys cannot be employed, while a very great consumption of fuel is necessary to raise the requisite amount of steam and create the draught, a totally different construction of furnace is required. Fig. 342 shows the construction of the furnace and boilers of locomotives, the general principle of which consists in burning the fuel in front and below the great body of the boiler, in a space surrounded on all sides except the bottom by a thin stratum of water, enclosed between strong wrought-iron or steel plates, and which forms a portion of the boiler ; the heated gases from the fuel, before escaping to the short chimney, are obliged to pass through a numerous series of metal tubes surrounded by the water of the boiler, by which con- trivance the heating-surface is enormously increased. Figs. 343-346 show the design of ordinary marine boilers in use. The Fig. 343. FiQ. 344. ^^^V' ■ M ^^^=^^-z-r-r-r>-z#IJ B»S£H»r-z-z-"------------d=g^ag''"iy^ ™^?^H JPSl ^ — ~\ J| 1 ^ ^^^^9^^^^a^^^All Ci 1 ^ 1 "uu iinsmnlBV^ ss door prevents the radiation and consequent loss of heat. The same result has been aimed at in a multitude of inventions for regulating the supply of air by furnace and ash-pit doors. A very simple door (Fig. 368), which swings both ways, has been invented by W. A. Martin for this end. Its application to a steam boiler is shown in Fig. 369. Fig. 369. There has been considerable development in the construction and im- provement of mechanical stokers since the year 181 3, when one of the earliest attempts was made. MECHAiaCAL fiTOKEES. 523 The following description of some of the most successful of these stokers is extracted from an excellent paper by Mr. J. W. Pearse (" Trans. Society of Engineers," vol. 1877) on ^^^ subject:* — " In the year 1822, Mr. John Stanley invented a stoker with a pair of fluted horizontal rollers for crushing the coal as it descended from a hopper in front of the boiler, at the same time equalizing the supply. Below the rollers, a three-armed fan was fixed, revolving on a horizontal axis, for the purpose of projecting the coal into the furnace. In 1834, Mr. Stanley, with the co-operation of Mr. John Walmsley, substituted indented for fluted rollers, and made the fan to revolve on a vertical instead of a horizontal axis. He also arranged the fire-bars so as to rock by means of gear con- nected with the stoker, and caused the steam in the boiler to act on a float in a siphon tube for stopping the feed when a certain pressure was attained. In 1838, Mr. John Juckes patented an arrangement of screw rams, by which successive charges of fuel were forced into tubes, where the coal was distilled before being discharged into the furnace. In 1839, he devised a narrow movable platform in the middle of the fire-bars, and hinged at the back end. On a fresh charge being propelled by a plunger on to this plat- form, it was forced up to the level of the fire-bars, both actions being performed by levers. In 1841 Mr. Juckes patented the invention with which;.his -name, is .'more; particularly -associated — viz., an endless chain of fire-bars, supported at each end by rollers, which are carried on trucks. As the chain passes under the boiler, it draws from a hopper its supply of coal, which is regulated by a door sliding vertically. In the next year, he some- what modified this idea and constructed his circular grate, made to revolve by means of a rack fixed to the circumference, and driven by a pinion. A portion of the grate is always outside the furnace, when the bars, which are pivoted at one end, fall down in succession to allow of the disengagement of the clinker, and are then raised again before entering the furnace. The fuel is drawn along much in the same way as in the previous arrangement. " In 1863, Messrs. Wilson and Smith caused their fire-bars, which were of the ordinary shape or nearly so, to travel backwards from the front of the furnace, so as to carry towards the bridge the fuel fed from a hopper pro- vided with a regulating damper; the bars then moved backwards, either singly or in pairs, the motions being given by two drums, fitted with pro- jecting arms, placed underneath the bars at the front end, and driven by any suitable means. "In 1867, Mr. Thomas Vicars, Mr. Thomas Vicars, jun., and the same Mr. Smith, patented some improvements on the preceding invention. Between the Wilson and Smith fire-bars, they placed others of shorter length moving backwards and forwards to a less extent than the travel of the former, from which they received motion. Again, instead of passing all the fuel from the front end under the furnace door, they supplied the whole or part of it from a hopper, situated at a higher level, and from which tubes descended to the grate. In some cases, part of the supply was led by a tube through the boiler itself, so as to deliver about midway between the front end and the bridge. " In 1870, Mr. Dillwyn Smith filed his specification. In the stoker asso- ciated with his' name, the coal is allowed to fall from a hopper in front of the boiler into a horizontal cylindrical receptacle, in which works a helical screw for giving the feed. In the case of a double-flued boiler, the screw is made right- and left-handed, the middle being placed just tinder the centre of the hopper ; and from the middle the diameter of the screw gradually increases until, at the ends, it becomes almost as large as that of the casing. At the ends of the screw shaft, and outside the screw, are projections for * See also "Jour. See. Ohem. Ind.," 1883, vol. ii. p. 71. 524 DEACON'S MECHANICAL STOKEK. more evenly distributing the coal as delivered by the screw. The pieces of coal are caught in falling by the vanes of a pair of fans, revolving towards each other in a horizontal plane, and are by them projected on to the furnace. As the pieces which are struck by the ends of the vanes are projected farthest into the fumade for a given size, and as the size of the pieces varies, it follows that an even distribution of fuel is effected over the whole area. The fan-shafts are driven by belts from a separate vertical shaft, actuated by a donkey engine or any available power ; and the shaft of the feed-screw is driven by a worm and worm-wheel put in motion by another vertical shaft worked by a strap off one of the fan-shafts, a pair of , cone-pulleys and a rod and lever serving to change the speed as may be required. "In the same year — 1870 — some improvements on the Dillwyn Smith stoker were made by Mr. George Frederick Deacon. It sometimes happened that, when large coal was used, some of the pieces were not sufficiently re- duced by the screw in one of their rectangular directions. To obviate this, a second but smaller thread was introduced between the main thread, and, like it, gradually increasing in size. It was also found that coal-dust some- times accumulated between the disc of the fan and the bottom of the casing ; this was counteracted by casting a narrow spiral feather on the bottom of the disc, and making some holes to admit the air, so that a sufficient draught was created to prevent the accumulation . At the same time, the fan shafts were reduced in height, chiefly to diminish the friction of the lower f oot- Fia. 370. step, which for this reason, as well as on account of the conducted heat from the furnaces, it was sometimes found difficult to keep cool. A non-conduct- ing substance was also introduced between the foot-step and the under side of the fan-case. One of the fan-shafts was, however, retained at its former height to serve for driving the others, the pulleys of which were kept as near the fans as the screw casing permitted. Each of the shafts had two bearings in a single bracket above the fan ; and the step was sometimes dis- pensed with altogether by forming a collar on the upper ends of the shafts. Sub.sequently, the fan-shafts were driven by toothed or friction wheels, enclosed in a chamber immediately below the fan-case, thus dispensing with all but one belt, because they were found to be deteriorated by the heat of the fire if the machine was kept standing for any length of time. Perhaps the most important addition made by Mr. Deacon was his deflector for causing all the particles of, fuel delivered by the screw to fall upon the fans. This consists of two castings bolted together, shown both in elevation and plan at Fig. 370, where A is the aperture through which the fuel falls, and F F the two fans. The particles are prevented from falling between the fans on the hinder side of their centre line by the inclined edge E of the plate D, and at the front side by the part B, which has a triangular section and curved base. The handle //, the stud of which passes through the slot S in the fan-casing C, allows the deflector to be moved both inwards and HENDERSON'S MECHANICAL STOKER. 52s outwards, as well as in a radial direction, until that position is found in which the most uniform delivery is secured. " The Henderson stoker, which incorporated Mr. Deacon's additions, con- tains stiU further improvements on that invented by Mr. Dillwyn Smith : and the two interests are now merged in the Mechanical Stoker Company. Additions and modifications were patented by Mr. Thomas Henderson in 1872, 1874, 1875, ^^^ s° 1^*® *^ ^^^ ^^^ °f l^s** year. Instead, however, of following these successive changes one by one, it will perhaps be better to describe the Henderson stoker as it now exists, with the latest improvements introduced. " Fig. 371 shows a, front elevation of the stoker as applied to a Lancashire boiler; Fig. 372 is a side view, partly in section; and Fig. 373 is a horizontal Fio. 371. section, showing the fire bars. The coal contained in the hopper A is fed down the two divisions, one in front of each flue, by means of a roller, which is modified in form according as it has to crush coal, or merely regulate the supply of slack. The particles, as they fall, are caught by the arms of two fans contained in the fan-case C, revolving towards each other in a hori- zontal plane, and are by them projected into the furnace, being distributed equally over the whole surface as in the Dillwyn Smith arrangement. The great improvement consists in the compact arrangement of parts, and the direct manner in which they are driven. Thus, a horizontal shaft B, made to revolve by a belt and pulleys, or in any other convenient manner, is carried by bearings immediately under the fan-case, and, by means of a worm in the centre, turns a worm-wheel Z* on a nearly vertical shaft E. 526 HENDEESON S MECHANICAL STOKER. FEISBIE'S GEATE AND FEEDEE. 527 This shaft carries a worm at its upper end, which gears with a worm-wheel F, keyed on the feed shaft, while it has another worm at its lower end for moving the fire-bars. The fans are driven direct by friction pulleys G G, on the horizontal shaft, working against a ring of leather, for preventing rattle, fixed to their hollow under-side. The fans, therefore, revolve at the rate they are speeded — about 200 a minute — but the feed is regulated by turning the hand screws //, which push in of draw out the front plate of the hopper, which is provided, if necessary, with an indented steel plate for facilitating the crushing of the coal. Sight holes are made in the fan-cases for affording means to ascertain that the fans are properly working ; and part of the bottom plate of the fan-case is constructed so as to be easily removable for taking out a fan in case of need. Sliding ventUators for regulating the admission of air, are also provided in the furnace doors, as shown in the front elevation. The two outside fire-bars remain stationary, but the others have a motion imparted to them by the crank of the short horizontal shaft K, links M, and projecting or connecting bar N. Every other fire-bar, 0, slides on the roller, Q, while the rest, P P, carried on the rocker R, and cross-bearer S, are, owing to the cranked shape of the rocker, made to rise and fall. The ashes and clinker are thus carried in one direction, according to the setting of the cranks. In the arrangement shown in Figs. 372 and 373, they are carried to the back end of the flue, on to a kind of dead plate formed by the ends of the lifting bars, which are continued beyond the sliding bars ; they gradually fall into the ashpit at the back, whence they are removed periodically by means of the hanging door T, worked by the chain V, from the front of the boiler. By this arrangement, not only is the supply of fuel automatic and continuous, but there is also an automatic stirring of the fire and cleansing of the fire-bars continually going on. According to the nature of the fuel and the demand on the boiler, the amount of rise and travel of the bars can be regulated by turning the hand screw W. At the same time, this double action of each alternate bar lifting and sliding keeps the interstices between them clear for the free admission of the air necessary for combustion. " All the foregoing mechanical arrangements for supplying fuel to fur- naces appear to have been „ designed in imitation of the ' ^'^' supposed perfection of hand- stoking — ^that is, the even distribution of a thin layer of coal over the whole sur- face of the fire, and as lightly as possible, so as to admit plenty of air for effecting the combustion. In the Frisbie feeder, however, a different principle has been adopted — that advocated by Dr. Arnott for domestic fire-places. This consists in supplying fresh fuel from below, and this, on being subjected to the heat of the incandescent mass above, evolves its gas to be consumed on rising through the fire. The other arrange- ments are for quick combustion ; this one is for slow combustion. In those the feed is continuous, whilst in this it is intermittent ; but the evil of admitting S28 frisbie's grate and feeder. iTutlinifl&iMTiyiiluliiltnlurniiiuiiiuiiii a volume of cold air on the top of the fire is avoided in this case as in the others. In 1868, Mr. Myron Frisbie, of New York, without claiming to originate the idea of feeding fuel from below, patented an arrangement whereby coal was thrust up underneath, and in the middle of the fire, and several of his machines are still at work, doing very good service. In 1875, Mr. James Millward Holmes and Mr. Walker, of Birmingham, introduced p into this feeder some im- ' '" provements, which chiefly consist in substituting gear for the direct action of a lever, whilst at the same time the whole machine is simplified. " Fig. 374 is an elevar tion of the improved Frisbie feeder as applied to a Cornish boiler; Fig. 375 is a plan of the fire- grate ; Fig. 376 a vertical section, showing the fuel- box in the position for receiving a supply of coal ; and : Fig. 377 shows the position it assumes while the charge is being thrust into the furnace from below. In Fig. 377, the feeder is shown applied to a Hoot's tubular boiler. In place of the usual straight fire-bars, there is a central circular apertilre surrounded by segmental gratings (shown best in the plan, Fig. 375), which are easily removable, whilst the whole annular pjg ^ arrangement of grate runs on fric- ■ ^ ■ tion rollers like a turn-table, and may be moved round by means of a crow-bar inserted in the holes shown at Fig. 374. Underneath the central aperture is the cylin- drical fuel-box A, mounted on forked side-frames B B, which swing on pivots F F attached to the base-plate along the centre line of the fuel-box. Cast in one with this fuel box is the apron C for re- taining the coal when the box is in its inclined position ready for being filled ; and jointed to it is the lever D, by the intervention of which the rod E, attaf;hed to the movable bottom of the fuel-box, is raised by the crank of the shaft to be after- wards described. A,B,C,B,a.TidF swing together on the pivots F F ; but the movable bottom of A is at the same time capable of rising and falling, being retained in its highest position by the catch G engaging with the nose of the lever B. The crank of the shaft H, mounted on bearings, also arranged along the central line of the fuel-box, carries a friction roller / which acts in its rotation upon the lever B, and consequently raises the movable bottom of the box. This shaft has also another pair of arms J J provided with pins THE FEISBIE FEEDER 529 which take into notches in the links K K jointed to the forked plates B B, and thus alter their position from inclined to vertical, and vice verad. The shaft is moved by the bevel gear and winch, either direct in a small machine, Fig. 377. or with spur wheel and pinion in a larger one, as shown in the vertical sections. Assuming that the fuel-box is filted with coal in its inclined position, the winch is turned so as to move the crank-shaft in the direction of the arrows in Fig. 376. The arms / J, by means of the links K K, draw the forked plates and fuel-box Fio. 378. underneath the central aper- ture, when the links rest upon the shaft, locking the box in its vertical position. As the crank continues to revolve in the same direction, the pins leave the notches in the links ; and the friction roller / comes into contact with the lever D, and raises the movable bottom of the fuel-box, thus forcing the coal upwards into the fire. The bottom is held in this position by the nose of the lever D engaging with the catch G. The winch is now ji;, turned the reverse way, which causes the shaft to revolve in the direction shown by the arrows in Fig. 377. The pins again engage in the links K K, thus pulling over into an inclined position the forked plates and fuel-box, which latter is followed up by the apron C for the purpose of retaining the coal in the fire-grate. As soon as the catch G strikes the bar L, it releases the lever B, and thus allows the movable bottom to fall to its first position, ready for another charge of fuel. Each Longitudinal section. S30 HOLEOYD SMITH'S STOKER. Fig. 379. fresh charge displaces that previously inserted, and thus has the effect of moving the whole fire. This action breaks up the cinder, and gradually carries any hard clinker that may have formed to the circumference of the grate, where it is removed at intervals by bringing in succession each part of the segmental gratings before the furnace door by means of a crow-bar. "It is evident that this ar- rangement is not applicable to the flues of Cornish or Lanca- shire boilers as they are usually fired ; but the Frisbie feeder has been applied with success to these boilers, either in the middle of their length, as shown at Fig. 374, or at one end, in a kind of combustion chamber made of fire-brick, communi- cating directly with the internal flue. There also seems now to be a reaction in some quarters in favour of externally flred boilers, especially that class in which two or more large hori- zontal water-tubes are connected by smaller vertical tubes, as shown with the Frisbie feeder attached, in sketch, Fig. 378. " The ' Helix ' fire-feeder, devised by Mr. Holroyd Smith, appears to com- bine, in a modified form, the two principles before mentioned — that is to say, the fuel is fed from below, and at the same time the feed is continuous. Its application diSfers from that of the Frisbie feeder in being more suitable for an internally Front elevation, partly in section. Fig. 380. Side elevation, partly in section. fired boiler, for which, in fact, it was specially de- signed. In this appliance, two or more of the ordi- nary straight fire- bars are replaced by a trough, in communication, at the bottom, with a tapering case of cylindrical section, in which works an Archimedean screw of modified form. The fuel contained in a hopper, placed in front of the boiler, is thus ab- solutely screwed into the fire underneath the incandescent coal, so that the gas is extracted by the heat, and burnt as evolved. The air necessary for combustion makes its way between the interstices of the bars, which are serrated on their upper edges for facilitating its distribution through the fire. VICAKS' MECHANICAL STOKER. 531 " Fig •?79 shows a front view of a Cornish boiler fitted with this arrange- ment, part of which is in section ; and Fig. 380 shows a longitudinal section of the boiler, with the ' Helix ' partly in section and partly m e evation. Ihe hopper H is in communication with the feed-trough F, which is placed across the front of the flue, and communicates in turn with two or more screw cases, according to the size of the boiler. In the diagrams, three of these cases are shown, containing the screws S S S. As this screw is of uniform pitch but of gradually decreasing diameter, suitably calculated, it delivers the fuel evenly throughout the whole length of fire-bars B B ; and the coal must be forced upwards through the longitudinal aperture, a^ that is the only outlet. Any large lumps of coal are crushed by the screw before being passed on. The cinders fall over the fire-brick bridge, and are removed once a day by withdrawing the damper B. ^ is an ordinary fire-door tor the inspection of the fire, for banking it up, or for use in hand firing, in case of a break down to the engine driving the feed gear or from any other Another mechanical stoker which has distinct features is that of Messrs. Haworth and Horsfall, called the Todmorden stoker. It has the usual hopper in front of the boiler, but between the hopper and the boiler front is a coking chamber built of fire-brick. Two sets of short bars advancing and receding alternately convey the coal through this chamber and on to a set of fixed water-tube bars in the boiler. These bars are in communication with the water in the boUer. They are semi-oval in shape, and are tested to 200 lbs. pressure per square inch. The fuel on these bars is moved towards the back of the fire by toothed rakes or scalers which rise up between the bars, cut into the fuel, and move it on about 2 inches. This takes place at Fia. 381. 532 McDOUGALL'S MECHANICAL STOKEE. intervals of a minute and a half and keeps the fuel broken up for the passage of air through it. The stoker of Messrs. T. & T. Vicars (Fig. 381) is the parent of a number of others worked on the same principle. This is the principle of moving Fig. 382. Wymm.m:mmmf!^^y:'-i!ffmm'jis^^.iimii^/!i>iii^%m fire-bars. They are arranged in groups of three, and are periodically pushed forward en masse, carrying the fuel with them, but are drawn back proctoe's and auld's mechanical stokers. 533 one by one, a bar of each third group being moved successively. A cam shaft running across the front of the furnace gives the necessary motion to the bars. McDougall's mechanical stoker (Figs. 382-384) works on the same prin- FiG. 384. ciple as Vicars' with some slight modifications ; and the same may be said of Auld's stoker (Figs. 385, 386), which, like McDougall's, has been success- fully applied to a number of boilers. Fig. 385. Proctor's mechanical stoker spreads a thin layer of fuel over the surface of the grate by means of the sharp movement or blow of a vane or rocking " shovel " of sheet-iron, which works in a chamber into which dross is fed from a hopper above. The movement is produced by a cam on a slowly revolving shaft which gradually draws the vane back, at the same time 534 PLAYER'S ANTHRACITE FEEDER. putting a spiral spring (which is attached to a lever on its axis) in tension. On the cam releasing the vane, the spring imparts a quick return forward motion to it, when it strikes the coal which has filled its chamber during its backward move, and projects the pieces into the furnace more or less according to their size and weight. The following figures* giving comparative results with hand fii'ing and mechanical stoking will be found of interest : — Lbs. Fuel Bupplied per Hour. Water erapo- rated per lb. of Fuel. Gallons of Water per Hour evaporated. Exit Gases. CO J. 0. Hand firing Stoker No. i 1) II 2 „ I. 3 • II ,. 4 419 323 419 523 617 6.417 7.274 7.076 6.898 5.856 269 23s 296 361 361 7-53 6.91 11.58 8.17 10.04 12.01 12.03 6.44 9SS 9.20 In giving these results, Mr. G. E. Davis remarks that it should be men- tioned that mechanical stokers are not smokeless when driven too hard. This description does not exhaust the list of mechanical stokers which are manufactured, but sufficiently shows the general principles governing their construction and use. Anthracite is much more difficult to burn under boilers than so-called bitu- minous coal; a much thicker stratum must be kept at a red heat, or the fire is liable to be extinguished; many varie- ties will not bear stoking without falling to a fine powder, which then arrests the draught ; others produce a great amount of clinker. Those which have but little residue and fall to pieces, like the majority of the Welsh and American anthracites, may be burnt in the man- shown at Kg. 387. A fixed grate, with Ind.," 1883, vol. ii. p. 71. ner proposed by M. Player, and " Jour. Soo. Chem. GAS-FIEED BOILERS. 535 straight fire-bars, is fed from a hopper kept constantly tilled with anthra- cite ; the fuel then forms a cone, from the end of the hopper to the grate, and descends as it is consumed, on the principle of the ancient " athanor." There is no door to the grate, the entire quantity of air being supplied from below the bars : the fuel, being heated as it descends the hopper, does not cool the fire, as is the case when it is introduced cold through a fire-door, and the decrepitation, if there be any, will occur before it reaches the grate. With some varieties, it would be necessary to supply some means of clearing the grate-bars of clinker. In burning fuel of this description, an accurate regulation of the draught is very necessary, so as to allow no carbonic oxide and as little uncombined oxygen as possible to escape by the chimney. Methods of using anthracite successfully in marine boilers have been introduced by Captain Hamilton Geary (" Journ. Roy. United Service Inst.," vol. xxi. pp. 956-968) and by Messrs. R. W. Perkins, of Swansea, and J. F. Flannery (see "Proc. Inst. N.A.," vol. 1880). GAS-PIBED BOILERS. General Considerations. — The use of gaseous fuel for firing steam boilers oflfers a ready and efiicient means of overcoming various imperfections which appear in other methods of firing, and of preventing some of the difficulties which attend these methods. The variation.s in the composition and quality of different coals, and even in difierent parts of the same seam of coal, the imperfections of hand stoking, the nature of the combustion of solid fuel, and the necessity of u.sing a large excess of air which it involves, all tend to make hand firing with solid fuel a very uneconomical process. The use of mechanical stokers ensures regularity in the charging of the fuel, and in its distribution on the grates, but only meets in a modified degree the other difficulties, whilst it, of course, does not alter the nature of the combustion taking place, or affect the varying composition of the fuel in use. It cannot be too clearly understood that, " in order to have complete combustion, it is necessary to have an inti- mate mixture of, and contact between, the particles of the combustible and those of the oxygen of the air, and also to maintain, during the whole period of combustion, a temperature sufficiently high to allow of chemical action taking place freely. The employment of solid fuel, although in small pieces, prevents the realization of the one, because it is only the surface of the pieces which can be in contact with the air ; and the employment of methods of combustion which necessitate the use of excess of air interferes with the other by the inevitable lowering of the temperature." "Again, with im- perfect combustion, such as is common to all boiler furnaces using solid fuel, boilers are exposed to the evil of the formation of a deposit of soot (mixed more or less with dust from the ash) on their heating surface (and on that of feed-heaters, where these are used), which considerably diminishes their evaporative efficiency. The use of solid fuel, moreover, causes additional wear to the boilers by the alternate heating and cooling which result from the operation of charging or stoking, and even from the combustion itself where solid fuel must first be volatilized and then burned in the same chamber." * The use of gaseous fuel is in direct coatrast with these features. By no other means can we obtain that intimate mixture and contact between the particles of the combustible and the supporter of combustion which are essential to complete combustion. The variations in composition of coal are overcome by the process of producing gas, the volume of gas in relation to • Gas Firing for Steam Boilers, by F. J. Rowan : "Trans. Mining lust. Scot.," vol. v. p. 218. 536 COAL AND GAS FIRKS COMPARED. the weight of solid fuel being so large that the composition of the gas re- mains to all intents practically constant, although that of the coal may vary. The formation of smoke and of sooty deposit is prevented, and the alterna- tions of high and low temperature, which are destructive to the boilers, are replaced by an even temperature which the steady stream of flame supplies. The temperature of combustion is not unduly lowered by the admission of excess of air for combustion, and consequently less heat is uselessly carried eflf by waste gases. It does not appear that the many advantages of this system of firing boilers have been fuUy realized in any practice with it hitherto carried out, although very good and economical results have been obtained in the case of several examples. On the other hand, coal fires, as applied to boiler firing, possess one advantage which renders them peculiarly suited to this work, especially where the steaming powers of boilers are forced, and that advantage consists in the large store of radiant heat which they yield when the coal is fully coked and the solid mass on the fire-bars is incandescent throughout. This quality of a coal fire has not been fully imitated in applying gas firing to boilers,' but in instances of forced combustion, which are only partial appli- cations of gas firing, its advantages are realized. Its importance has been demonstrated by an experiment shown by Mr. W. Anderson, and before him by Prof. Tyndall, where the radiation from a gas-flame is shown to be greatly increased by the presence of a solid body, which becomes incan- descent or glowing in the midst of the flame. Connected with this are the questions of the calorific intensity of the fire, and of the temperature to which the heating surfaces of the boiler are exposed. These questions are not identical, for determinations of calorific intensity do not include any statement of the amount of radiant heat produced by the combustion of a fuel, or of the evaporative efiect of this radiant heat. The calorific intensity of an ordinary coal fire, where twice the theoretical quantity of air required for combustion is admitted, is stated by Mr. D. K. Clark* to be about 2614° F., whilst the calorific intensity of ordinary producer gas is variously put at 1800° to 2000° by different authorities. Invariably, however, more air than 24 lbs. per lb. of coal is admitted to coal fires, and the heating efiect of these fires is still further reduced by the cooling effects produced by opening the furnace-doors for stoking and cleaning the grates ; but yet it appears that, given a restricted boiler heating surface, but a good chimney draught, more steam may be produced by a forced coal fire under such circumstances (though at the cost of a greatly increased expenditure of fuel) than by gas firing as ordinarily applied — viz., with cold air for com- bustion. This shows that the full heating effect of a coal fire is not repre- sented by these temperatures, which denote the calorific intensity of the fuel.-f On the principle that a steam boiler may be justly regarded as a heat engine, it is evident that the higher the initial temperature, T, is, the better, it being understood that this is the temperature actually ope- rating on the boiler surfaces, provided that in maintaining this temperature we do not allow the waste gases to escape too rapidly or to be too hot when escaping, and thus unduly raise the final temperature, t. In several instances in which gas-firing has been tested against hand-fed coal fires, under similar conditions as to amount of boUer heating surface and of chimney draught, the results have shown a higher evaporative efii- ciency in the gas-fired boiler — that Is, a larger quantity of water evaporated from the same surfaces in a given time. A greater weight of water has also been in some cases evaporated with gas per lb. of coal used, although, * " A Manual of Eulea, Tables, and Data, &c.," third edition, 1884, p. 408. + See On the Estimation of the Caloiiflo Value of Solid and Liquid Fuel, by F. J. Rowan : " Jour. Soo. Ohem. Indus.," vol. vii. p. 195. EELATION OF SURFACE TO TEMPEEATUEE 537 where cold air has been used for combustion, the difference between the two systems of firing has not been very great in this respect. Where the air for combustion has been heated by waste heat from the exit gases, a much higher temperature of combustion and increased economy of evaporation have been obtained. In those cases in which gas firing with cold air has shown economical results, it will be found that the steaming power of the boiler has not been forced, either from insuflB^ciency of chimney draught or from its not being necessary to obtain more steam than was being supplied. The question, however, arises, how it happens that, if the temperature of a solid coal fire is higher than that of the flame obtained from producer gas and cold air, the gas flame should be able to evaporate more water from the same surfaces in the same time. This apparently anomalous result will be found to be due to the existence in these cases of a proper relation or ratio between the extent of heating surface, the rate of travel of the flame and hot gases over the surface (or what is the same thing, the duration of con- tact between them and the surface), and the initial temperature or the tem- perature of the fire. The proof that this proper ratio exists will be found in the final temperature or the temperature of the escaping waste gases, which will show the amount of cooling which has taken place. It is evident that with an initial temperature of 2000° F. and a final temperature of 400° F., we should have a better thermal result than where with 3500° F. initial, we have 1200° F. final, the difference being as 0.8 is to 0.65. Mr. Anderson has, moreover, directed attention to the fact that the conductivity of substances varies inversely as the temperature and probably as the absolute temperature, and hence the rate of transfer of heat to the water of a boiler will be slower in proportion at the furnace end than at the chimney end, but to what extent it is impossible to say, because the mean temperature of the boiler plates is unknown. He thinks that it is certain, however, that it is below even the melting-point of lead, or 630° F., because lead safety-plugs are frequently used even in locomotives, and they do not melt out unless there be a want of water. He says, " if we assume the mean temperature of the plates at the furnace-end to be 500°, and that of the chimney-end to be 350°, then the rate of transmission at the cooler end will be about 18 per cent, greater than at the hotter. Were it not for the imperfect absorption of radiant heat and reduced conductivity caused by high temperature, ebullition over and about the furnace would be so vio- lent that' uncontrollable priming would surely take place." This also serves to explain how a better result may be obtained with the moderate heat of a gas fiame with cold air than with a hotter fire ; and it further shows that in order to secure economy we must consider other elements be- sides the mere heat of the fire. It follows directly from these facts that higher temperatures of combustion demand greatly increased surfaces for transmission of heat to the water, or a longer period of contact of the flame and hot gases therewith, in order to reduce the temperature of the exit gases, which is necessary in order to obtain the largest useful effect from the thermic cycle of operations. Regarding the amount of evaporation which can economically be ob- tained from the heating surface of boilers, Mr. W. Anderson remarks that in practice 12 square feet of flue heating surface, measuring only the half , over the gases, or 10 square feet of small tube surface, measured in the same way, will transmit the heat necessary to evaporate i cubic foot of water ( = 62 lbs.) per hour from and at 212% which he reckons as one boiler horse- power; and that where the escaping gases have a temperature of 400° F., a mean velocity of 10.8 feet per second over the surface is admissible for them, which corresponds with i o square inches of flue section per boiler horse-power, for a consumption of i lb. of coal to 10 lbs. of water converted into steam. 538 EXAMPLES OF GAS FIRING. Mr. Thomas Box, in his " Treatise on Heat " (London : Spon, 2nd ed. 1876, pp. 85, 86), takes |rds of a cubic foot, or say 40 lbs., of- water evapo- rated from 60° into steam of any pressure as equivalent to one indicated horse- power, and gives a formula and table showing that in boilers of fifty horse- power and upwards, about to. 6 square feet of effective heating surface are required for this work. This is equivalent to an evaporation of 4 lbs. of water from each square foot of heating surface, and also, if 8 lbs. of water are evaporated per lb. of coal, to a consumption of ^ lb. of coal per square foot of effective heating surface. Mr. D. Dixon, engineer to Messrs. Gadsden & Co., of New York, who had considerable experience in this application of gas firing, arrived at similar conclusions, and his observations have been, by the courtesy of Mr. H. A. Gadsden, made available for this work. Mr. Dixon remarks that the conclusions to be drawn from their experience are : — " I St. That more water can be evaporated per square foot of heating surface with hand firing than by gas, unless the air is heated, so that as high a temperature is obtained with gas as can be derived from a coal fire ; the amount of evaporation depending on the temperature and not so much on the volume of the heating gases." In this conclusion Mr. Dixon, how- ever, does not take into account the relation of extent of surface to the temperature, initial and final, of the gases, and it is, therefore, not universally true. " 2nd. That if an evaporation of more than 7 lbs. of water per square foot of effective heating surface is. obtained by gas firing, it is at an enormous expense of fuel in proportion to the increase. All the data at hand lead to the conclusion that 4 lbs. per square foot is the most economical quantity at which to work a boiler." Mr. Dixon adds, " This holds good as well in the case of hand firing." " 3rd. Brick burners give a better result than iron ones. It is most important that combustion should be complete before the gases touch the boiler. An arch built over the burners underneath the boiler, extending back 3 or 4 feet, for the gases to burn against, is very effective, a few holes can be left in it to allow a little heat to pass through. The arch, when heated, acts as a sort of regulator." " A combustion chamber built out in front of the boiler is effective, especially with a tubular boiler — or a deep combustion chamber, with the point of mixture of gas and air not less than 6 feet from the under-surface of the boiler." These conclusions were arrived at in the year 1883 as the result of several trials of gas firing which were carried out in America, and will be described subsequently in this section. Practical Examples. — The firing of the steam boilers in ironworks was one of the first uses to which the gases from blast furnaces were put, as Fio. ^8q. soon as their recovery was commenced. An ordinary method of carrying out this application of gas fuel to boilers is illustrated in Kgs. 388-390. USE OF WASTE GAS IN lEONWOEKS. 539 The gas is usually conveyed to the front of the boilers by over-head mains, with vertical branches leading downward, as is shown in Figs. 389 and 390. The air for combustion is generally admitted tlirough gratings or other open- ings in the furnace door, through which it is drawn by the draught of a Fia. 390. chimney, but it is sometimes supplied from a fan or blowing engine, by means of a blast-pipe leading into the furnace or ash-pit. In order that the gas should be always ignited, some solid fuel is usually kept burning near the gas and air inlets. The experience gained in such ironworks with this system of **■ 39i' firing boilers showed its advantages in some respects. Repairs to the boilers were lessened, and the life of the boilers was prolonged, whilst their steaming power was increased. The economy of fuel, as compared with hand firing with solid fuel, could not be investigated, for the simple reason that the quantity of gases used could not be measured. To the ironmaster, however, the use of the waste gases in this way was wholly an economy — a waste product completely taking the place of so much coal or dross. Some of the earliest comparative trials of gas firing applied to boilers, of which we have records, were carried out in France. Many attempts had been made, both in France and in Britain,* to introduce forms of appa- ratus or arrangements of furnaces by means of which the formation of smoke would be prevented — or, as they were termed in those days, smoke- consuming apparatus. These experi- ments, no doubt, paved the way for the introduction of gas firing, the earliest apparatus designed for this system as applied to steam boilers having been that of M. Beaufume. The gas-producing part of this apparatus has * See " Notice eur les Appareils fumivores, appliqui^s aux Foyers des Maehinea-Ji-vapeur et notamment aux Machines locomotives employaut la Houille," par M. Tnrck : M4m. et Compt. Bend, de la Soc. des Ingen. civile, No. 36, pp. 585-628 (Paris, 1S66). 540 beauftjme's apparatus. been already described (see ante, p. 253). Figs. 391 and 392 show the com- bustion arrangements in connection with the boDer setting. The gas was delivered from the gasifier A by the pipe m (Fig. 392), whence it was admitted to the fire-place by numerous small streams through the passages s (Fig. 392), formed by the bricks B (Kg. 391). The air for combustion was led from a fan into the passages k, j, and 1 to p, in which Fig. 392. it was heated, and from the latter it was allowed to escape into the combustion chamber n by the small passages s. It was thus also broken up into small streams, and well mixed with the gas. Part of the air supply was admitted to the grate b of the gasifier by the passages h (Fig. 392). The late Professor Macquorn Eankine communicated, in October 1857, to the Institution of Engineers in Scotland,* the results of experiments made with the Beaufume apparatus, which proved its practical usefulness. The Table on p. 541 gives the results of the experiments made at the Imperial Arsenal at Cherbourg by order of the French Government, under the supervision of MM. Guesnet, Admiralty Engineer, and Sochet, Director of Naval Construction, by whom a report was issued. Four series of experiments were made, the first three being with the boiler of the establishment called the Northern Forge at Cherbourg. This boiler (of 12 h.p.) had 167I square feet of heating surface, and its ordinary grate surface was 12^ square feet. The Beaufum6 gasifier had a grate surface of 5 J square feet, the fuel being allowed to be 27 J inches thick on the grate. The gasifier was 1 1 J feet high, and measured 1 o feet by 6 J feet on its width and depth respectively. * " Trans. Inst. Eng. in Scotland," vol. i. pp. 14-18. RESULTS WITH BEAUFUME S SYSTEM. 541 The fan delivering the air supply was driven at one thousand revolutions per minute, and supplied the blast at a pressure of 1.97 inch of water. The fourth series of experiments was made with one of four tubular boilers lying in the boiler-yard at Cherbourg ready for the steamer Antdope. MM. Guesnet and Sochet certified that, although there were some inconveniences connected with the system, yet the apparatus worked with great regularity ; no smoke was made, and a saving of 38 per cent, was realized. They estimated the saving which might be reckoned on with certainty in ordinary work at 33^ per cent. Professor Rankine supplied some additional details not given in the Report — viz. : In all the experiments the water supplied to the boiler was cold ; and as it is usual to reduce the results of experiments of this kind to the results which would have been obtained if the boiler had been supplied with water at a temperature of 212° F., 18 per cent, must be added to the evaporation in series i, 2, and 3, and 16 per cent, to that of 4 ; this making the results in one case 9.8 lbs., and in the other 10.5 lbs, of water evapo- rated per lb. of coal. In other experiments, one of the best results obtained, when water of about 100° was supplied, was equivalent to an evaporation of nearly 12 lbs. of water, from 212°, per lb. of coal. The boiler used in the first three series of experiments was evidently a bad one, because its usual rate of evaporation, when coal was burned on the ordinary grate, was only 4.85 lbs. RESULTS OF EXPERIMENTS MADE AT CHERBOURG. Dura- tion Total Amount Water evaporated No. Date. of Experi- ments. of Fuel con- sumed. Kind of Fuel. during the Experi- ment, Hour. per lb, of Coal. Observations. 1856. h. m. lbs. lbs. lbs. lbs. Series No. i. r 2 May 7 „ 8 8 30 831 9704 1,0144 Large New- castle coal 4,620 4,905 S43-S S6i-9 4,865 4835 1 The boiler of the forge heated by the ordi- nary furaace. Series No. 2. 3 „ 28 8 45 9084 Large New- J castle coal j 5,640 644.4 6.210 The boiler of the Ibrge 4 „ 29 8 30 1,0584 7,110 836s 6.710 heated by the Beau- 5 „ 30 8 30 1,021 6,621 778.5 8.260 fuin6 apparatus. Series No. 3. 6 June 2 8 30 847 Small coal, Oapfliff 6,131 875.6 7.240 The boiler of the forge 7 ,> 4 8 30 8114 (Newall's Llanelly) 6,744 791.8 8,300 heated by the Beati 8 „ 6 8 761 S.S18 689.7 7,250 fum6 apparatus. Series No. 4. 9 10 II 12 ■3 ,- 12 .. IS „ 16 .. 17 „ 18 7 5 IS 7 IS 7 6 1,500 849 1,235 i;23S 1,0584 f Newcastle / 12,751 7,353 12,218 11,618 9,788 1,821.6 1,400,4 1,676,2 1.659-7 1,631-3 9-03S 8.066 9.820 9-407 9.24s ^ A tubular boiler ■S ;g heated by the ' |St3 Beaufuml appa- K ratns. 14 „ 23 S 1,0584 coal 9,420 1,884,0 8.897 |. -2, 36 out of 106 ^ss ^ tubes closed 15 -, 25 9 2,029 17,719 1,969.5 9.038 ■ e a, 16 „ 26 2 30 4,762 \ 6,921 1,885.7 9,898 g 1 42 out of 106 I ^ tubes closed. 17 ,- 29 3 45 653 6,923 1,864.0] 10.600 The Siemens gas producer, which was introduced about the same time as Beaufum^'s, was also applied to boUer firing, but we have no published 542 MINAEY'S APPARATUS. record of results of this application of it. It has not proved itself so well suited for this class of furnaces as for others. At a very early period, the late Mr. W. Gorman worked in this direction, and in his first paper " On the Combustion of Coal,"* described experiments which showed the advantage in economy of fuel to be obtained from the use even of a modified form of gas firing. The apparatus he employed was an ordinary steam-boiler furnace, with a closed ash-pit, having blast delivered under the furnace bars and through openings in the interior surface of the double casing of the furnace door. With ordinary air supply and chimney draught the same furnace and boiler using 28 lbs. coal, evaporated 93 lbs. of water, whilst with the blast applied and firing arranged on Mr. G-orman's system, the same weight of coal evaporated no and 123 lbs. of water on different occasions. Mr. Gor- man displayed an intimate acquaintance with the processes of combustion, and in this paper foreshadowed the further developments in the direction of gas production, which were soon introduced. M. E. Minary, an engineer of Besan9on, published in i868t an elabo- rate treatise on combustion in manufacturing furnaces, in which, after explaining the general principles and chemical reactions connected with combustion, he described the construction and the action of his " apparatus for double combustion," as he called it, which was a gas producer with mechanical air supply, both for combustion in the producer and for com- * " Trans. Inst. Eug. in Scotland, " vol. ii pp. 70-80, and plate vL t Publication industrielle des Machines cndUa et appareils, &c., vol. xviii. (Paris, 1868). FICHET'S EXPEEIMENTS. 543 bustion of the gas in the furnace. The gas-producing part of his apparatus has been already referred to (see ante, pp. 256-259), and in Fig. 393, the arrangement of gas producer with grate bars and closed ash-pit, and forced air supply for the double combustion, as applied to a French boiler, or chaudiere h bouilleurs, is shown. M. Minary's general conclusions on the subject of combustion are curious and interesting. He thus enumerates them : — 1. In all furnaces, the transmission of heat is primarily due mainly to contact of the hot gases with the fuel, with the walls of the furnace, and with the heating surface of the boilers. 2. The radiation of fires is only a reflex action, following the anterior transmission of heat by the contact of the gas. 3. It could only be otherwise for combustible bodies whose products of combustion are not gaseous, such as iron and certain metals, the oxides produced having a considerable power of radiation. Regarding the utilization of the heat of furnaces, he concludes that : — 1. The apparatus in which combustion takes place should be perfectly distinct from the one in which the heat is utilized. 2. This apparatus should be preserved from cooling by a thickness of walls sufficient to minimize the loss of heat outwards. 3. The maintenance of a high temperature in the combustion chamber is a guarantee of perfect combustion of the gas, and it is consequently neces- sary to avoid reducing it for the deceptive advantage that radiation from the gas might produce. 4. The gases escaping under these conditions from the combustion chamber at a temperature so much higher than it, suffer no loss of radiation, as they take with them all the heat which has been produced, and as they are in contact with the surfaces of the generators we can recover thus nearly aU the heat which the fuel can give. M. A. Fichet* made many experiments and trials in the course of his investigation of this subject, and communicated the practical results, when he had attained to an assured success, to the French Institution of Civil Engineers. M. Fichet at first endeavoured to apply to boiler firing, with merely some modifications in details, the arrangements of gas producers and com- bustion chambers which he had already introduced with good results in gas-works. He found, however, that the rapid cooling of the fiame and hot gases by contact with the boiler surfaces, produced phenomena which necessi- tated a complete change in his combustion apparatus. When using non- bituminous fuel, and admitting, for combustion of the gas, a very slight excess of air above the theoretical quantity, the flame was extinguished on contact with the boiler surfaces; but analysis of the waste gases showed the presence of both free oxygen and carbonic oxide, proving that the gas had not been completely burned. With caking coals, smoke was produced, in addition to these unsatisfactory results ; but in the arrangements for firing gas retorts, these difficulties had not been encountered. Trials were there- fore made of successive forms and arrangements of combustion apparatus, and the nature of the products of combustion was always observed by analysis, so that the completeness of combustion in each case was estimated. The calorific value of the gas from the generator was also measured by the calorimeter and compared with the actual result of combustion. By these means, M. Fichet arrived at various general conclusions on the subject of the combustion of fuel, which are given in his interesting memoir, and at a " " Etudes snr la Combustion et sur la Construction rationelle des Foyers induetrielles," par A. richet: Mim. et Campt.-rend. des Travaux de la Soc. des Ingin. civils, 1874, pp. 670-7H (Paris). 544 I'lCHET'S AEEANGEMENTS FOR GAS FIRING. form of apparatus for boiler firing, which worked successfully, giving, as he says, complete combustion without excess of air being inixed with the pro- ducts of combustion. The principles on which this apparatus rests are given as follows : — They consist in intimately mixing at a high temperature the combustible gases and air, both being divided up into thin streams, this mixing taking place in a chamber built of refractory material in which combustion (or rather inflammation) must be allowed to be complete ; and, in allowing this completed mixture of gas and air to come in contact with the boiler surfaces only when its inflammation was complete, and nothing remained but to utilize the heat which was thus being produced. Three types of this arrangement were successfully introduced — viz., as applied to a French boiler with feed-heaters (chcmdiere a bouUleurs et richauffeurs), to a cylindrical boiler with internal furnace, and to a vertical Fib. 394. boiler with " Field " tubes. Figs. 394 and 395 show the first of these types Fig. 394 being a horizontal section on the line cd of Fig. 395, and Fig. 395 being a vertical section of the line ab of Fig. 394. The first trials with this type of boiler were made at the works of M. E. MuUer at Ivry. The cylindrical portion of the boilers used was 3 feet 7 inches (i m. 10) in diameter, with heaters or accessory chambers 24 inches (60 centimetres) dia- meter — the lengths are not given — and having a heating surface of 560 square feet (52 square metres), not reckoning the surface of the feed- water heaters. A producer, in the form of a modified Siemens sloping grate, of which A was the fuel chamber and b the ashpit, was placed in front of the boiler, below the floor level. The fuel was charged every hour in quantities of about 2 cwts., by means of the charging box and cover shown. Air was admitted GAS-FIEED FRENCH BOILERS. 545 to the grate through perforations in the double swing-door shown at the entrance to the ash-pit. The gases produced from the fuel ascended by an inclined passage into the cham- ber g (Fig. 394) below the boiler, ^'«- 39S- their rate of admission to this chamber being regulated by a damper r. The roof of the chamber g was constructed of flat pieces of fire-brick, arranged to form a grating, which provided a number of narrow openings for the escape of the gas into the combustion chamber c above, see Fig. 395. The air for combustion was supplied by the pipe a (Fig. 394) laid in the chimney flue f, in which it was heated by the hot waste gases. This pipe led into the chamber as, below the gas chamber g, from which the air ascended by passages on each side of g, see Fig. 395, meeting the gas in c, where combustion com- menced. The heat imparted to the air in the pipe a and subse- quently in the chamber a and passages on either side of the gas chamber, caused it to issue from the orifices into c with considerable velocity. It was divided into thin str eams and met the streams of gas issuing in a different direction, thus N N 546 GAS-FIEED VEETIOAL BOILERS. causing a thorough mixture. Although this arrangement worked well and gave good results,. yet analysis of the waste gases always showed the presence of free oxygen, which was due to the admission of a slight excess of air. This excess was at last traced to leakage of air through the pores of the bricks composing the building of the boiler setting and the combustion chamber, when it did not gain admission by cracked seams formed by con- traction during drying. The chimney draught sufficed to produce this fil- tration of air through the furnace walls, even when the air supply was delivered from a blower. A boiler of the same dimensions, but fired by an ordinary grate, placed alongside the gas-fired boiler and supplied with the same coal and water, gave the means of instituting a comparison between the two methods of working. The boiler with ordinary grate evaporated almost constantly about 6 lbs. of water per lb. coal, the coal being the ordinary bituminous kind of the North of France and of Belgium. This rate of evaporation, M. Fichet remarks, is in accord with that obtained from the experiments carried out at Wesserling and Winterthur, and published in the Bulletin de la Society industrielle de Mvihouse in 1873. The gas-fired boiler showed an evaporation of from 8.6 to 9.2 lbs. of water per lb. of coal. This, M. Fichet remarks, is equal to an increase of useful effect amounting to 48 per cent., or, otherwise, to an economy of 32 per cent, for an equal production of steam. The feed heaters of the Ivry boiler had not a sufficient amount of heating surface to cool the waste gases below 225* C. (437° F.). Fig. 397. Figs. 396-399 show the arrangement for boilers with internal furnace, C being the combustion chamber, and iiii numerous openings in an TABLES OF FIOHET'S EESULTS. 547 inclined door lined with fire-brick, which closes the outer end of the chamber c. The openings i i are formed by wrought-iron tubes, which conduct the air into c ; in this case the chimney draught was relied on to carry the supply of air into the combustion chamber. Figs. 398 and 399 show other arrangements of this door and its apertures, /and r, Fig. 396, are the flues for the waste gases leading to the chimney. The combustion chamber c is lined with fire-brick for some part of its length. The arrangement for one class of vertical boilers is shown in Fig. 400. The gas ascends by the passage g and the damper r, and meeting the fiie- brick cover d, it escapes by horizontal openings into the combustion space c, into which also air is delivered from a series of orifices connected with an annular passage a. No results are given of the working of boilers of the two latter types, but M. Fichet gives tables showing the details of continuous working for a week with the French boiler. These tables are reproduced in the following TABLES OP RESULTS OF GAS FIRING APPLIED TO STEAM BOILERS. Description of coal used . . Moisture ia coal (in the rougli) Analysis of coal(dr^){g„\^^_^^7.72| . . Ash Heating surface of boiler ... Average pressure of steam . ... Weiglit of coal burned in 11 hours. „ water evaporated in 1 1 hourd „ „ „ per lb. fuel „ ato°a (= 32°F.)- . „ „ evapcirated per sq. met. of surface „ ashes (dry) in 11 hours . Giand Hornu • 2.21 % . 100.00 7o . 936 7o 52 sq. met. = S59.74 sq. it. 5 atmos. = 75 lbs. per sq. in. 820 kil. = 1,808 lbs. . 6.900 kil. = 15,224 lbs. . 8.40 lbs. 8 80 lbs. . 120 kil. . 72 kil. = 158.7 lbs. Hour . Temperature Analyses of Gases. Temperatures Observed. Decrees Centigrade. of Of Feed -o . TS . oS Obaer- Water U ^ c s « w fe ■i'i vatiOD. in Tank. Place where Sampled. 0" o' 8 ■43 1 i fc-g -& e^l i^^ « "^ & l|« "1* ■ § M s 5 •iioai Bwnbg jad -sqi oS ureefg •0„otrj9,BMPMJ •(Bon -qi led paiBjodBAQ; is^bm - 00 00 ^ &. 8 6\ unOH rad paan [Boo o O CO o to ■pasn IBOO iB}ox 1 ^ ■8 ON ■moH »d pasn i«)b^ 00 « ro •pasn nrfM. moj, 8 "ft "$ ■j9}Bi\ pea J JO omjBiadoiax 11°. {\i .601 o?„80i) •/aaiupio 0} sasBO 9:}8BA!L JO am^Biaduiax II 1 1 {■3. o°of ) •Basso 8aidB083 m 'OO 8 "§ Mliog JO png }B am^Biadoiai 11 1 00 {■S. „oo6) •SBO raanpojj ni «0D P4 g ■^ 8 VO •SBtiMMiroajopnsr uiojj naafl sb aaiB[ j jo mo^oo Q - - - •anij janog m ^qSncjQ jo jnnouiy ram. of water. 6 (qoni f ^noqe) VO VO ■lUBajgjoajnssaij s S'S. "1 6 s, a •gmsBO JO uiOMOg uiojj jaanpojj m lanj jo jqSiaH 5o "in "in VO s ^ 5 '5 - = n •BjnOH HI IBUI, JO no!}Mna » 2- •^ ^ ^^ CO 1 11 •0- tn CLARK'S EEPOET ON GAS-FIEED BOILERS. 565 mounting used in these cases, and also as applied by Mr. Wilson (who sup- plies the illustrations) to boilers at Messrs. Tangye's works and elsewhere. Other results of gas-firing will be found noted in Trans. Mining Inst, of Scotland, vol. vii. pp. 57 and 162, and in the Report of Mr. D. K. Clark to the Committee of the Smoke Abatement Exhibition (published by Smith, Elder j four boilers . „ „ per hour . Water evaporated per lb. of coal . Net „ „ by 3 boilers in full steaui, exclusive of steam for producer . Ditto ditto from and at 212° Hand Firing. Gas Firing. — 33.80 0. feet — 6.76 „ — 407.82 „ — 81.56 „ 5.71 lbs. 6.56 lbs. 6.02 lbs. net 6.79 lbs. 7.16 „ ■ The following data may be re-stated for comparison : — Coal consumed per boiler in full steam per bour . . Water evaporated per boiler in full steam pej- hour Water per lbs. of coal from and at 212° F. 163 lbs. 14.93 c. feet. 6.79 lbs. 258.6 lbs. 24.94 c. feet. 7.16 lbs. net. Fig. 423. Elevation in section of gas-firing arrangement adopted first by Gadsden & Co. " It is shown that the boilers in full steam did two-thirds more evapo- rative duty by gas firing than by hand firing, and with 5 J per cent, more evaporative efficiency, after allowance made for steam consumed in blowing CLAEK'S REPORT ON GAS-FIRED BOILERS. S6; the producers. It is also shown that the weight of steam consumed by the , . ■?'?.8o X loo Tiv„ .,. producer is ^^ = *^'*- 424- ^ 407.82 8.29 per cent, of total quan- tity generated in the four boilers. " The total evaporative efficiency of the boilers with gas firing, if no deduction be made for the demands of the producers, is expressed by 6.56 lbs. of water per lb. of coal, on an equivalent of 7.81 lbs. from and at 212°, which is 7.81 - 6. 79 = .98 lb., or 14.4 per cent, more effi- ciency than was obtained by hand firing. This is an expression of the absolute difference of efficiency in favour of gas firing. The practical difference after making the needful allow- ance is, as above stated, 5^ per cent. "Smoke was frequently visible at the top of the chimney during the trial with gas firing, ranging from No. i to 7 of the Plan partly in section of J^ig. 423. smoke abatement scale. '°' '^'^' "This was evidence of deficiency of air, or of imperfect mixture of the air and the gas. In fact the furnace doors of Nos. 2, 3, and 4 boilers were 2j inches open for the whole time to make up the proper supply of air. I should add that the attendant on the gas firing com- plained that he had to force the fire in order to keep up the pressure of steam. He called attention to the small- ness of the back flue of the boilers. " At intervals, of course, no smoke was visible with gas firing, and there is no reason Front elevation— paitly in section— of Fig. 423 why, under fitting con- ditions, gas firing should not be conducted entirely without smoke. " Although the results of the comparative trials prove so far as they gb 5.68 AMERICAN GAS-FIEED BOILERS. ib favour of gas firing against hand firing, yet they are not quite conclusive, as the experimental boilers were evidently not worked under the most fitting conditions for either hand firing or gas firing. Considerably more Fid. 426. Section at EF, Fig. 427. Fio. 427. Section at AB, Fig. 426. than 14.93 cubic feet of water should have been evaporated per hour in each boiler, and a greater evaporative efficiency than 5.71 lbs. of water per lb. of DIXON'S REPORT OP AMERICAN TRIALS. 569 coal should have been shown. At the same time, it is probable that with flttirjig conditions the gas firing also would have exhibited greater efficiency. " On the whole, I am disposed to accept the percentage of advantage in favour of gas firing ascertained by the comparative trials, namely, an abso- lute difference of 14.4 per cent., or a net difference of 5^ per cent, in favour of the gas firing. " This deduction fully harmonizes with the best result of Mr. J. H. Darby's experiments at Has Power Colliery, which shows a greater abso- lute efficiency of 9.85 per cent, in favour of gas firing, or a net efficiency fo 4 per cent, in its favour. " Looking to the evidence of greater evaporative efficiency and a greater rate of production of steam, it appears that the Wilson system of gas firing is worthy of a more extended trial. " In estimating the pecuniary saving by its adoption, the cost of main- tenance of the two producers may be taken at 10 per cent, per year on the Fig. 428. beciioa at CD, in Figs. 426 aud 427. first cost = ;£^3oo. Against this, with interest on the capital, is to be set off the saving in cost of fuel and its attendance." In the trials referred to previously as having been conducted in America by Mr. Dixon, under Messrs. Gadsden & Co., there were " eight boilers, each 24 feet 6 inches long by 3 feet 10 inches diameter, with two return flues each 17 J inches diameter, all connected by steam and feed drums, over one continuous grate 41 feet long by 6 feet broad, with eight firing doors. The flame, after passing under the boilers, returns through the flues, a brushing in front connecting them with stacks in pairs. The heating surface by American formula amounted to 3,300 square feet, and the effective surface, according to rules in Box's 'Treatise on Heat, about 2,100 feet. " The consumption of coal by hand firing was about 5,400 lbs. per hour, with an evaporation of about 25,500 lbs. of water per hour, or less than 4f lbs. per lb. of coal, and about 1 2 lbs. per square foot of efiective heating surface. 570 DIXON'S EEPOET OF AMERICAN TRIALS. " Four producers were first applied, burning between i,6oo and 1,700 lbs. of coal per hour, the gas and air being admitted to the boilers by iron burners as shown in Figs. 423, 424, and 425 (pp. 566, 567). With the four producers clean and working well, the evaporation amounted to 14,500 to Fio. 429. Section at AB, Fig. 430. Fio. 430. Plan in section at CD, Fig. 429. 15,000 lbs. per hour, or say 8| lbs. of water per lb. of coal, or 7 lbs. for each square foot of effective heating surface. " Three more producers were added, first with the sapie combustion arrangements, and afterwards with those shown in Figs. 426, 427, and 428- DIXON'S EEPOET OF AMERICAN TRIALS. 57 1 (pp. 568, 569), which was subsequently modified by alterations shown in Figs. 429, 430, and 431, and finally in accordance wth those shown in Figs. 432, Fio. 431. Section on line EF, Figs. 429 and 430. Fig. 432. Section at EF, Fig. 433. 433, 434, and 435 ; but, with the seven producers working fuU, the greatest evaporation obtained was 20,000 lbs. of water per hour. An eighth 572 DIXON'S REPORT OF AMERICAN TRIALS. producer was finally added, but it was found that there was no additional evaporation by the combustion of the additional quantity of gas. In fact, Fig. 433. Plan in section on line GH, Fig. 432. Fib. 434. Section on line CD, Fig. 433. six producers gave as large a result as seven, whilst more steam per lb. of fuel was obtained when working four producers." DIXON'S REMARKS ON DARBY'S TRIALS. 573 Mr. Dixon remarked as follows on these results, as compared with those given in Mr. Darby's Report : — " Darby's Report confirms the conclusions I have drawn. Observe that in his trial No. i, 750 lbs. of coal per hour were Fig. 435- Section on line AB, Fig. 432. consumed, or nearly 2 lbs. for every square foot of effective heating surface, and only 5.8 lbs. of water per lb. of coil. In trial No. 3, only 438 lbs. of Fig. 436. Elevation of single-flue boiler arranged for gas firing — Gas flue in longitudinal section. coal were consumed per hour, less than i lb. for each square foot of heating surface, and 8.6 lbs. of water per lb. of coal, which is very fair. In the 574 DIXON'S EEMARKS ON DARBY'S TRIALS. first instance, at considerable expense of gas, he succeeded in getting each effedtive square foot to evaporate nearly lo lbs. per hour. In the latter, the Fig. 437. Section of single-flue boiler arranged for gas firing — Gas flue in cross secdon. Fig. 438. evaporation was 8J lbs. per square foot per hour, which is more than a DIFFERENT FORMS OF GAS-FIEED BOILERS. 575 boiler should be called upon to do. Had the consumption of fuel been reduced to J lb. per square foot, or 220 lbs. per hour, the evaporation would probably have been lo lbs. of water per lb. of fuel, or 5 lbs. per square foot of surface per hour, which is the economical point. " In our trials, our first, with four producers, was nearly equal to Darby's third and best ; whilst our worst, as far as economy of fuel was concerned, with eight producers was but little under his first. Our not being able to properly control chimney draught would account for the difference in both cases." Some interesting results of the application of natural gas to boiler fir.ng are given by Mr. A. Carnegie in his paper on Natural Gas in the Jouri.al of the Iron and Steel Inst., vol. i. 1885, p. 174. In order to illustrate the application of gas to difierent forms of boilers, Figs. ,4.36 to 446 are added. Figs. 438 to 440 showing the method of firing egg-ended boilers, and Figs. 441 to 446 showing an added brick combustion chamber outside the boiler flues for Cornish or Lancashire boilers. Fig. 439. The only other plan to which we shall here refer, on account of its great interest, is that of the gas-fired boilers at the Engineering Works of Messrs, David Kowan & Son in Glasgow. At first, one boiler was tested with gas firing against a similar boiler alongside fired by hand, and com- parative results were thus obtained. Both were subsequently fired by gas and continue to be worked on that system. The boilers are constructed of steel, each 10 feet 6 inches long by 8 feet 6 inches diameter, and contain eighty-two tubes of 4 inches external diameter, extending from end to end of the boilers. The tube surface is 901 square feet, and the area of shell which is exposed to heat is 133 square feet, the total heating surface being thus 1,034 square feet. With hand firing, there were 33 feet of grate area, whilst with the producer there are 1 5 square feet ; so that formerly the ratio of heating surface to grate surface was 31 to i, whilst with gas firing it is 69 to I. Originally the flues were arranged in the hand-fired boiler so that the flame and hot gases returned from the back of the boiler to the front directly through the tubes, and then were conducted along the sides to the 576 DIFPEEENT FOEMS OF GAS-FIKED BOILEES. Fia. 440. GAS-FIRED BOILER WITH BRICK COMBUSTION CHAMBER. 577 chimney-flue at the back. As thus arranged, a week's trial gave 5.651 lbs. of water per lb. of coal as the evaporative rate. The course of the hot gases was altered by causing them first to return to the boiler front by the side flues and finally to reach the chimney flue by the small tubes, and the result of this alteration was to raise the evaporative rate to 7 lbs. of water per lb. of coal. It was found that in the old arrangement the tubes extinguished the flame, and that a large quantity of unconsumed gas escaped to the chimney which, with the altered arrangement, was able to burn in the side flues. By means of experiments made with boiler tubes placed over a jet of Fio. 442. crude gas from a Siemens producer, Mr. W. Anderson found that 6 feet was the maximum length which a boiler tube of 3 inches diameter should have if combustion were intended to go on in it. It is probable that Mr. Anderson used vertical tubes, which might be expected to give a better result than the same tubes in a horizontal position. In Messrs. Rowan's boiler, the tubes were horizontal, so that in spite of their slightly larger diameter the extinguishing effect may have occurred within Mr. Anderson's limit of length. In the gas-firing arrangement, gas is generated in a rectangular pro- p p 578 GAS-FIRED BOILERS. ducer 5 feet by 4 feet, the grate surface being 15 square feet, and the coal being kept at a depth of 2 feet to 2 feet 6 inches on the bars. Air is supplied from a Root's Blower to the ash-pit of the producer, which is closed by an air-tight door, and the gas is led from the producer over an inverted arch to the under side of the boiler, where it meets a supply of heated air. Ignition here takes place, and the flame passes along under the boiler, returns along the side flues, and thence through the tubes to the chimney-flue. In order to heat the air for combustion, there are twelve rows of fire-brick tubes, 3 inches internal diameter, placed in the bottom of the boiler setting and heated there by radiation from the com- bustion chamber, and the air from the blower is directed through these — 10. 443. first through five and then back through seven— to the combustion space, where it meets the hot gas from the producer. The opening for escape of the gas from the producer to the combustion chamber is about 48 inches by 3 inches, or 144 square inches, which, with 15 square feet of grate surface, is nearly 10 square inches of opening for every square foot of grate. This, Mr. James Rowan, who described this plan to the Graduate section of the Inst, of Engineers in Scotland, con- sidered to be a good proportion, as the gas was not restricted in its escape by the opening being to ' small ; and, on the other hand, the producer and chamber were not turned into an ordinary air-furnace by the opening being too large. The surface of the arch occasionally collects a deposit of tarry soot, GAS-FIEED BOILERS, f 10. 444. 579 I'lo. 445. P P 2 58o GAS-FIKED BOILER AT MESSRS. ROWAN'S. Fio. 446. which is, however, easily cleaned off; and, except just at the period of charging fresh fuel, the process is entirely smokeless. The charging is carried out by hand through the firing- door shown in the illustrations, but there is no reason why a hopper with bell-cone, or similar arrangement, should not be used. This has the advantage of preventing the ingress of cold air to the producer, or of allowing. the escape of much gas. The evaporative results obtained with this arrangement were, ^n one trial, 9^ lbs. of water evaporated per lb. of coal con- sumed ; and in another, which extended over three days, using a good quality of splint coal, 10.8 lbs. of water were evaporated per lb. of coal burned. The latter trial was made simultaneously with the trial of hand firing referred to, when 7 lbs. of water were evaporated per lb. of coal, the same quality of coal having been used for both boilers. It thus Fio. 447. appears that the gas-fired boiler evapprated 51 per cent, more water per unit of coal burned than the hand-fired boiler. The following are the total quantities of coal used and water evaporated by the gas-fired boiler in the first trial referred to, which lasted from i p.m. on February 11, 1882, to the same hour on the 18th of that month. The quality of coal used was ordinary " tripping " or unriddled coal, from the Hamilton coal field. During the trial the engine was working for 58 hours. GAS-FIEED BOILER AT GLASGOW. 581 Water evaporated . . . 185,123 lbs. Coal burned .... 19,488 lbs. = 9.499 lbs. of water evaporated per lb. of coal burned. This arrangement of Messrs. Rowan's is shown in Figs. 447, 448, and 449, Fig. 447 being a plan in section, Fig. 448 a longitudinal elevation in section, and Fig. 449 cross-sections on different vertical lines on Fig. 447. Boutigny proposed the following arrangement for raising steam : — Noticing that all bodies, solid or liquid, evaporate only by means of their surfaces, and taking advantage of this fact, he proposed to employ a cylinder the bottom of which was semi-spherical, and the top tightly screwed down, to which the usual accompaniments of a steam-boiler were attached — viz., steam- and feed-pipes, man-hole, safety-valves, steam-gauges, &c. Fig. 448. The cylinder contained from five to seven tin-plate diaphragms with the edges turned up ; they were alternately convex and concave, pierced with small holes from below upwards. The water, before arriving at the bottom of the cylinder, where it assumed the spheroidal form, had passed over a great surface, falling as a fine rain from one shelf to another, collecting in the one towards the centre, and in the next towards the rim. The arrangement for collecting the steam between the two last shelves, tended to maintain the whole interior at the same temperature, and to pro- duce steam of any degree of tension. The cylinder was heated alone for a few minutes, after which a small quantity of water was admitted, and in twenty or twenty-five minutes more the apparatus was ready for work. 582 ROWANS GAS-FIRED BOILER. BOUTIGNY'S BOILEE — EVAPOEATION. S83 Fio. 450. The following are the details of an experiment with this boiler : — Duration of the experiment . . 9 hours Weight of coal burnt . . . 182 lbs. (81 kilogr.) Weight of water evaporated . . 790 lbs. (350 kilogr.) Temperature of the water used . . 39° 0. Pressure . . . . . .10 atmospheres The coal was not of good quality, and was really equal to 6,000 heat- degrees per kilogram, and, assuming with Morier that 50 per cent, is the maximum available effect, we have — 81 kil. » 6,000 X 0.50 = 243,000 degrees. Now, 351 kilograms water, under the above conditions, contain 351 kilograms (550 + 1 - 1') = 242,892 degrees ; and in this formula t = +i8i°C. t'=+ 39° C. hence the loss is only 108 degrees. Fig. 450 represents a perpendicular section of the entire boiler, with a horizontal section through G G ; A, feed- pipe ; D D D, seven metal shelves, four of which are convex and three concave ; E, water-gauge ; M, steam-gauge ; P, pipe for cleaning the boiler ; S, safety- valve ; V, steam-pipe. Similar methods of raising steam have been proposed by Belleville in France, Perkins in England, and Her- reshoff in America, but they have not attained any permanent success in practical work. Evaporation. — The object of evapo- ration is to remove one or more volatile ingredients from a mixture in order to obtain the fixed or less volatile. The operation may be carried on either with or without the aid of artificial heat, in open or closed vessels ; in the latter case, it is more properly called distillation. The air seldom contains the maxi- mum amount of moisture which it is capable of retaining in the state of vapour, and liquids exposed to it evapo- rate more or less quickly, according to the extent of surface exposed. In describing the methods for obtaining salt from the water of brine springs, in a future volume, an account will be given of the system adopted for spontaneously evaporating the weak liquors, which consists in exposing the liquid in very shallow ponds to the air and sun ; or by causing it to flow over a very extensive surface of twigs in the graduation houses. No fuel is employed in this process of evaporation. An artificial current of air at the ordinary temperature produced by mechanical agency has also been employed to produce evaporation where a high temperature would prove injurious to the product. Evaporation in Open Fans. — The most simple method of evaporation by the agency of fuel, is to place the liquid in a pan or vessel immediately over a fire, or exposed to the flues through which the smoke and hot gases from the fire are passing to the chimney. Although evaporation takes 584 EVAPOEATION OF VITEIOL IN OPEN PANS. place at all temperatures, it proceeds much more rapidly as the heat increases and it has been proved both by calculation and experiment that less fuel is required to evaporate a given weight of liquid at the boiling point than to evaporate the same weight at any lower temperature. The general practice, however, is to employ a much larger heating-surface in evaporating vessels than is usual in steam boilers, and the smoke and hot gases are cooled down as much as is compatible with a good draught before escaping to the chimney. There is no economy of fuel in using very deep evaporating vessels, as the quantity of liquid evaporated, for the same amount of fuel consumed, depends on the extent of surface exposed to the fire or source of heat, and the rapidity of convection. When evaporation takes place at the boiling temperature, the rate of evaporation will not be materially affected if the vessel be closed, with the exception of a sufficient aperture for the escape of the vapour ; but there is always a loss of heat if the exposed surface of the cover is not itself covered with some non-conducting substance. The open pans employed in concentrating oil of vitriol are shown in Figs. 451, 452, which are from sketches suppUed by Messrs. C. Tennant Fio. 45 1. & Co. Fig. 451 shows a sectional elevation of lead evaporators utilizing the spent heat from a furnace, over the fire-place of which is a platinum pan for concentrating the acid. The lead evaporators prepare the acid for running Fig. 452. into the platinum pan. Fig. 45 2 shows lead evaporators for concentrating acid up to 1.70 sp. gr. The fall of the pans is from the fire-place instead of towards it, as was customary some years ago, this having been found to work better and more economically, the strong heat of the fire being required to drive oflF the water from the weak acid, while the spent heat finally concentrates the stronger acid. Surface evaporation in close furnaces, as described below, is the plan adopted in some large vitriol works in this country. OPEN PANS FOE BEINE. 585 The large shallow pans employed in evaporating brine for the pro- duction of salt are shown in Fig. 453, and the arrangement of the flues conveying the smoke and hot gases in Fig. 454. These pans are flat quad- rangular vessels, constructed of sheet-iron, often 60 feet long by 30 in breadth, and by the arrangement of the space below them, the flame from the two fumades is brought into contact with the entire bottom surface of the pan. In order to increase the rapidity of the evaporation, the pan is nearly covered by a large wooden funnel, opening above into a vapour- Fio. 454. chimney I ; the lower part of this hood or funnel is constructed of planks, which can be turned up so as to admit the air freely to the surface of the liquid from the side opposed to the wind. The vapour has sometimes been carried into the chimney instead of escaping by a separate funnel ; but when 5 86 SUEFACE EVAPOEATION, it is produced in considerable quantity, the draught is liable to derangement. This is likewise the case when the vapour is conveyed to the ash-pit. In some localities, large drying-flats for prepared chalk or whiting are con- nected with these salt-pans, so as to employ the waste heat. Where it is necessary to concentrate large quantities of weak liquors, which are of such a nature as not to be injured by the products of com- bustion and the particles of dust and carbon they carry with them, the flame and heated gases may be carried over the surface of the liquors. This plan of surface evaporation is practised with weak alum-liquors, as shown in i'ig. 455. It was originally adopted in consequence of the sediment which Fig. 455. Fig. 456. is deposited during the process attaching itself to the bottom of the ordinary open pans, and causing their rapid destruction. These tanks are constructed of bricks, cemented together with a mixture of lime and lixiviated alum- shale. They are very shallow, but of great length, so as to offer an extensive surface to the current of hot air and gases. An open pan is sometimes placed above them, which serves as a feeder for the lower pan. Allied to these are the evaporators forming part of the incinerators used in paper works for the recovery of the waste soda lyes. Amongst the more important of the plans in use are the in- cinerators of Arnot and of Porrion; whilst a very promising system* of applying gas firing to incinerators has been introduced at some works in England with undoubtedly good results. Fig 456 represents a pan-furnace for boUing down liquors to dryness, where the material is not injured by an excessive temperature. The interior of the furnace is lined with sheet-iron, or rather consists of a long sheet- iron pan, capable of holding 2,000 gallons of liquid. The foes cc are at each end, the steam and products of combustion passing off by a Hue , and the condensed water flows off into E. Another method of evapo- rating weak liquora is shown in Fig. 460. Here the steam from a vacuum-pan is intro- duced into a series of straight copper pipes, placed one above another^ their ends being fixed into cast-iron boxes. The steam is admitted through the pipe Z>, and passes in the direction indicated by the arrows, escaping finally at E. The weak liquors to be evaporated are allowed to fall in a fine shower from a perforated trough B, on to the heated pipes. A large surface of liquid is thus exposed simultaneously to the hot surface and to the air, and is concentrated while the steam in the interior of the pipes is condensed. When it is desirable that the air should be totally excluded from the liquor to be evaporated, and that the evaporation should proceed at a tempera- ture lower than that at which the liquid would boil when exposed to the atmospheric pressure, recourse is had to the vacuum-pan. Fig. 461 represents this apparatus as employed in concentrating sugar- liquors ; X is a vessel for regulating the supply to the pan, whilst the vessel Mhs. intended for collecting any portion of the liquor which may accidentally boil over; A is an outer cast-iron jacket, between which and the inner copper vessel B steam is admitted ; D is the copjier worm, also supplied VACUUM EVAPORATING APPAEATUS. Fio. 460. 589 Fig. 461. 590 EVAPORATION BY MULTIPLE EFFECT. with steam from the valve F. The vapour is pumped off by an air-pump through E, which is assisted by the condenser shown in Fig. 375, or by some arrangement similar in principle. / is a thermometer for indicating the temperature of evaporation; K & baronieter or vacuum-gauge, for ascer- taining the pressure in the pan. The temperature at which the liquor would boil, under atmospheric pressure, is about 250° F., and it is reduced by the vacuum to 150° F. or less. Iivaporatioii by Multiple Eflfect* — The value of steam as a heating medium has already been referred to (pp. 478-^484), and the fact that the boiling point of liquids varies with the. pressure has long'been known and is the basis of the use of the ordinary vacuum pan. It is only within a com- paratively recent period, however, that these principles have been taken advantage of in anything like a complete way in connection with the evapo- ration of liquids. The lowering of the boiling point of water by diminution of pressure is shown by the following Table : — The temperature of water boairig at atmospheric pressure is . . . 212' ,, ,, der 5 inches vacuum is . ' • '95 " »» j» *o ,, ,, . 25 26 27 2g 29 29J 18s «i6o ISO 130 120 112 100 72 52 other liquids follow a similar rule, but have different normal boUing points; and even water, when containing sugar or other substances in solution, has its temperature of boiling at atmospheric pressure raised. It is apparent from these facts that if in several vessels there are different degrees of vacuum produced, we can have a descending scale of boiling temperatures, so that vapour of comparatively low temperature can be utilized as it is produced. " The different boiling points of a liquid under different pressures can thus be utilized, by making the vapour given off in boiling the contents of the iirst vessel at a certain pressure form the -heating agent of the liquid boiling in the second vessel at a lower- pressure, the vapour from this second vessel forming the heating agent in the third, and so on." This principle was applied in what is known -sis the Hillieux^system, and governs all form's of what are now called " Triple-effilt " (or triple effect) apparatus. The Eillieux system utilized " the latent heat of the vapour of liquids boiling under a low vacuum to boil a second pan working under a higher vacuum. The usual limit to this system is four pans, thus utilizing the latent heat four times and reducing the fuel to nearly one-fourth of that required for open evaporation or single vacuum pans. As generally arranged, all the boiling liquids in the system are under a partial vacuum ; the first under about 5 inches, from which' the vapour is taken to boil a second under 1 2 inches vacuum ; from this to a third, boiling under 19 inches vacuum, and from this to a fourth, boiling under 27 inches vacuum." " In liquids liable to injury by heat, the total variation of temperature available under ordinary conditions is that between the temperature of steam at 5 lbs. pressure per square inch (227° F.) and the temperature of a solution at 30° Baum6 boiling under a vacuum of 26 inches' (rgi^'F.) — a total of 96° F. With a triple effect (or three vessels), however, there is steam at 5 lbs. pressure in the drum or shell of the first effect, and the liquid in the tubes — ^at atmospheric pressure — boils at 227° F., giving off vapour at * On Evaporation by Multiple Effect, by F. J. Eowan: "Jour. Soc. Chem. Ind.," 1889, vol. viii. p. 32, 'TRIPLE EFFfiT" APPAEATUS. 591 212° F. This vapour at 212° F. passes into the shell of the next effect and boils the liquid in the tubes of this effect under 14 inches vacuum, giving off vapour at 161° F. This again passes to the shell of the third effect and boUs the liquid in the tubes under a vacuum of 26 inches, the boiling point of this liquid (supposing it to be a concentrated solution of 30° Baum6) being 131° F. It is a point worth noting that where the liquid is a solution of sojids in water, the vapour will always be at the temperature of boiling water at the pressure to which the liquid is subjected at the time, whilst the liquid itself will be warmer. The total difference of temperature in evaporating liquids liable to injury by heat being, as mentioned above, 96° F., whilst the amount of heat transmitted through the tubes (and therefore the work done) is practically proportional to the difference in temperature, it is evident that the same wM-k is done whether the whole of this difference is in one vessel or is subdivided among several vessels. In other words, a double, triple, or quadruple effect can only do the work of a single effect the size of the first vessel of the multiple effect ; but it does it with ^, ^rd, or ^th of the quantity of steam or fuel respectively." Fig. 462 illustrates the arangement of triple effect apparatus manu- factured by Messrs. A. and W. Smith & Co., of Glasgow. This apparatus Fig, 462. «^w«!>5?iw W&' ST^R PLE errcT appa ^atus-^ ^ is generally composed of three vessels, which may be placed either vertically, as shown in the illustration, or horizontally. Each of the vessels has a calandria, or tube-chamber, filled with small brass tubes, in the lower part of the vessel. The steam, which under ordinary working conditions is merely the exhaust steam from the engine connected with the apparatus, is admitted to the lower part of the chamber surrounding these tubes and acts upon the liquor inside the tubes, the level of the liquor being three-fourths of the height of the chamber. The steam or vapour rising from the surface of the liquor in this first pan enters into the tube chamber of the second pan and boils the liquor in it. The steam or vapour from the surface of the liquor in the second pan enters the corresponding tube-chamber of the third pan, and boils the liquor which it contains. The vapour from this 592 MULTIPLE EFFECT EVAPOEATION. pan is drawn through the condenser by means of a vacuum pumping-engine, which acts on the other pans also. In its normal working it will be observed that the steam admitted into the first chamber is the actual heating medium for the three vessels. The apparatus is generally fitted with isolating valves, so that any of the pans can be thrown off at pleasure. The temperature is highest in the first pan and lowest in the third ; whereas the quality of the vacuum is arranged in the reverse order, it being highest in the last pan, which is nearest to the condenser and vacuum pump. This distribution of temperature and. vacuum is said to be well suited to the evaporation of sugar liquor. The pans are fitted with eye- glasses, gauge-cocks and other appliances necessary for the manipulation of the liquor from one pan to another, and for testing its consistency during evaporation. The whole apparatus is generally mounted on a cast-iron framework composed of columns and girders in order to render it accessible. Although in the form of apparatus just described, the liquor being evaporated is inside the small tubes, and the steam used for heating it is outside, in the triple-effilt apparatus as ordinarily arranged, the reverse order has usually been maintained. The influence of the highly ingenious Yaryan apparatus has doubtless been felt in this and other details, but the action of the Yaryan evaporator is suflEiciently distinct to demand separate description. The great objections found to exist against multiple-effect apparatus as usually constructed are the high temperature to which the liquor is exposed in the first vessel, and the length of time which is required to treat the volume of liquid contained in it. In the manufacture of sugar with the ordinary triple effect the heat of the first effect, which reaches to nearly 200° F., combined with the long time to which the liquor is subjected to it, is a fruitful source of "inversion" of the sugar. With the Yaryan system, however, frequent tests with the polariscope demonstrate that there is no inversion, and consequently no loss of sugar from that cause. The Yaryan Evaporator. — ^The ingenious invention of Mr. Homer T. Yaryan, of Toledo, Ohio, U.S.A., has met with a very large measure of success from its first introduction in America in 1886, and has in large measure superseded all previous attempts to produce economical evaporation by m^fichinery. Mr. Yaryan adopts in his apparatus the two principles of " Evaporation in a Vacuum " and " Evaporation by Multiple Effect." The evaporator itself consists of a series of straight tubes, passing from end to end of a shell or drum, and coupled together by an ingenious arrangement of " pockets " to lorm coils, the main advantage gained by this design being the great ease with which the straight tubes can be examined or cleaned. As a rule, the coils consist of an odd number of tubes, the inlet being at one end of the evaporator and the outlet at the other. At the outlet end of the evaporator is a separating chamber, in which the liquid discharged from the tubes is completely separated from the vapour. Below the separating chamber is a " collecting chamber" into which the liquid flows, whence it is drawn, by the superior vacuum, into the vaporizing coils of the second effect, in which it undergoes a second process of evaporation by means of the vapour which comes, through the vapour pipe at the top of the separating chamber of the first effect, into the shell of the second effect. This principle of " multiple effect" can be repeated in the Yaryan to an almost indefinite extent, its limit being gauged only by the commercial aspect of the question. The vaporization in the Yaryan apparatus differs from that which occurs in previous systems in that it takes place in the interior of the above- mentioned vaporizing coUs, the heating agent being outside the tubes ; and THE YARYAN APPARATUS. 593 as the rate of the feed of liquid to be evaporated is arranged so that it cannot fill these coils, there is never any depth of liquid to be displaced by the vapour in its endeavour to escape from the heating surface. Tn addition to this, the rapid circulation induced by the formation of the vapour in the interior of the tubes, promotes a movement which brings into play the whole of the heating surface in a manner which has never before been effected. Tests taken from Yaryan evaporators in operation have shown an evaporation per square foot of heating surface more than double that of any evaporator previously invented, whilst by the new principle embodied in Mr. Yaryan's invention, evaporation by multiple effect can be carried ful-ther in his apparatus than in any other. As an evidence of the practical results obtained by the Yaryan evapo- rator, over one hundred machines, with a daily evaporating capacity of over 3,000,000 gallons, and concentrating a variety of liquids, have been started during the last two years, and all are giving great satisfaction. The applications of the Yaryan evaporator are very extensive, as the following list will show, the liquids named having all been successfully dealt with iT-Solutions of sugar, glucose, glue, glycerine, beer worts, grape must, waste alkali liquors from paper mills, bark extracts, dyewood extracts, Fio. 463. tannin, liquid beef, pure caustic soda, tank waters from slaughter-houses, ias. &c. It has also been applied to the concentration of mUk and to the production of distilled water from sea or impure water. In fact, it can be applied to almost any liquid requiring concentration. The general arrangement of the apparatus ■ is shown in Fig. 463. As will be seen, it consists of three or more horizontal vessels mounted on a light staging. It is provided with a condenser and pumping engine for maintaining a high vacuum in the last P^m, and the engine is also provided with small pumps for feeding the liquor into the first pan, and withdrawing it, after concentration, from the last. The action of the apparatus will be understood from the diagram. Fig. 464, giving a simplified section through one of the pans and " catch-alls." The heating tubes, surrounded by steam, are divided into units or sections, known as " coils," and consisting of five tubes coupled at the ends so as to form one passage. One of these " coils " is shown in the illustration. Its 594 THE YAEYAN APPAEATUS. action may be taken as typical of that of all the coUs in the pan, of which there may be any number proportional to the work to be done. The liquor enters the first tube of the coil in a small but continuous stream, and immediately begins to boil violently. It is thus formed into a mass of foam, which contains, as it rushes along the heated tubes, a constantly increasing proportion of steam. As the foam and steam cannot escape by the inlet end of the coil, and as steam is being continually formed, the mixture is propelled forward at a high velocity, and finally escapes from the last tube into an enlarged end chamber, known as the separator. This is provided with baffle plates, against which the mixture of steam and liquor impinges on issuing from the tube. The liquor falls to the bottom, whilst the vapour passes on to heat the next pan. The arrangement described is said to give an almost perfect separation of the liquor and vapour ; but to make doubly sure, and to avoid the chance of losing any sugar, the vapour is next passed through the special form of catch-all shown in the illustration. This is also a part of Mr. Yaryan's invention. Here the vapour is divided by tubes into a number of small streams, each of which impinges against the end wall of the chamber, giving up any drops of liquid carried over. The vapour itself escapes by the central pipe. This catch all is found in practice to prevent any detectable Fig. 464. loss even when used for liquors far more liable to foaming than those dealt with in sugar manufacture. The advantages claimed for the Yaryan apparatus are many and im- portant. The duty of each square foot of heating surface is twice that which can be obtained in apparatus worked in the ordinary method. There is only a small quantity of liquor in the apparatus at any one time, and the circulation is rapid and compulsory. These are both very important points, seeing that the action of heat on sugar is injurious in proportion to the time during which it is applied, as well as to the intensity of the heat. The apparatus is found in use to be practically automatic and requires the mini- mum of attention. It can be started and stopped in far less time than that needed with the older apparatus, which will contain hundreds or even thousands of gallons of liquor. The economy of fuel realized in the Yaryan arrangement of multiple- effect evaporation is thus stated by the patentees. A well-proportioned steam boiler, fired with good fuel should evaporate 8| lbs. of water per lb. DISTILLATION. S9S of coal. Each pound of steam condensed in the first effect will evaporate one pound of water, less the heat required to bring the liquid to be evapo- rated to its boiling point. If the initial temperature of the liquid were, say, 50" F., and the boiling temperature, say, 140°, there would be a loss of 90°. As there are about 966° of latent heat in steam, this loss would amount to nearly 10 per cent. Or, supposing the liquid is at the boiling point when it reaches the apparatus, every pound of steam condensed in the first efiFect evaporates i lb. of water, and in turn the vapour thus produced evaporates i lb. of water in the next effect, and so on. There is, of course, some loss by radiation of heat ; but, as the vessels are small and easily lagged, this is reduced to a minimum : 16 lbs. of water will therefore be evaporated in a double-effect Yaryan apparatus, 235 lbs. in a triple-effect, 30 J lbs. in a quadruple-effect, and 37 lbs. in a quintuple-efibct for each lb. of coal burned under the boiler. With the ordinary vacuum pan, or steam pan boiling, only 8J lbs. of water will be evaporated per lb. of coal used, whilst with direct firing not more than 5 lbs. of water per lb. of coal can be evaporated. Distillation. — The separation and collection of a more volatile ingre- dient of a mixture from others which are less volatile or more fixed, is called distillation. When the distillate is liquefiable, the operation may simply consist in raising the temperature of a mixture sufficiently to evaporate the volatile ingredient, and in condensing the volatile product, either to the liquid 01' solid condition ; or it may involve the decomposition of the sub- stance heated, and the condensation of the products of decomposition, when it is termed destructive distillation,. The latter process is sometimes carried on for the sake of the volatile products, as in the manufacture of gas and gaseous combustibles. Where a solid body is thus treated and the products are liquid or gaseous, the process is called dry distillation, and is generally destructive. It is called sublimation when the product condenses from the state of vapour to the solid condition, without passing through the inter- mediate state of liquid. The distillatory apparatus, or still, is constructed of brick, fire-clay, iron, copper, or platinum, according to the nature of the substances to be operated on. The escape-pipe for the vapour is generally large, as it is desii-able that the vapour should leave the still with as little obstruction as possible. Air and water are almost the only agents emploj-ed for condensation, and the condensing-pipes are generally of iron or copper, except in those cases where corrosive substances are condensed, such as acids, when stone-ware pipes and receivers are employed, or, in the case of vitriol, when glass, platinum, and lead are used. The dimensions of aU the parts of the appais^^is will depend on the quantity of vapour required to be produced and condensed in a given space of time, when the specific and latent heat of the products will necessarily form an important item in the calculations. The still is generally heated by the direct action of the fire and flues ; but steam, of high or low pressure, applied either to the outer surface, or by a coil of pipe to the interior, or by both conjointly, may likewise be employed as a source of heat. Either high or low pressure steam, or super- heated steam, may be brought into direct contact with the substance to be distilled, where the products are of such a nature as to be easily separated from the condensed water ; and lastly, the facility with which vapours rise under diminished pressure, renders distillation in a vacuum desirable in special cases. The same general principles may be applied to the setting of stills over the fire as those which are applicable to boilers ; the larger the heating surface exposed the better, provided that a good draught is secured and the QQ 2 596 DISTILLING APPARATUS. Fig. 466. contents are not liable to be burned by the direct action of the fire on the material of the still. This, however, is frequently the case, as in the pre- paration of spirits, where a rapid distillation is required ; rousers frequently Fig 46q ^®'°S employed to D ^5=—^^^^ /-■ prevent the solid contents from adher- ing to the bottom of the still . Fig. 465 repre- sents the simplest form of still, with a worm-pipe condenser. A is the still ; B the head ; C the refrige- rator, kept constantly supplied with cold water, and containing the worm for the condensation of the vapour. For ordinary purposes, the diameter of the still may be 2^ times its height, and the neck about J of the diameter. It may -be set in the manner shown in Fig. 466, when the flame, after leaving the bottom of the still, separates at 2 into two flues, which enclose it on either side and meet again at 4, where they again branch into two upper flues, 5 5, before entering the chimney at 7. Fig. 467 illustrates a copper till(of a capacity of 1,556 gallons) f the old pot type, a.s it is now ised by the distillers of fine malt /^hisky in the Highlands of Scot- hnd. This still measures 9 feet 6 inches in diameter, and 19 feet high, and is set upon brickwork, with the openings for furnace door and flue not shown. This illustration is that of the still made by Messrs. John Miller acts as a rectifier. The heater C, when filled up to the level of the cock m, contains the exact measure of wash for charging the still ; the contents can be con- Fio. 467. stantly agitated by the rouser i. The still and heater being both charged, the vapour will at first be completely condensed in passing through the worm g, and flowing into I), will close the aperture of q with a water- or spirit-valve. When the contents of C become so hot that no more conden- sation occurs, the vapour will be forced to escape through the liquid in I) : this becoming heated by the constant current of vapour, will itself soon boil, and evolve vapour of greater strength than the liquid it is leaving, which is then condensed by the worm in £. In this manner, by one operation, spirit containing about 60 per cent, of alcohol is obtained. An improvement upon this apparatus was made by Pistorius, who intro- duced a second still over the same fire. The vapours from the one still were paased directly into the wash in the other, which was thus soon brought to 598 DEEOSNE'S STILL, the boiling point, and the vapour was condensed in a rectifier similar in principle, but somewhat modified in construction, to the one just described. Alcohol of 80 or go per cent, was thus obtained in a single operation. Schwarz and others have improved on the apparatus of Pistorius, but the greatest perfection in the apparatus for distilkition has been attained in the arrangements of Derosne and Coffey, which have superseded all others in large distilleries. The advantages presented by these forms of apparatus are that they not only at once yield the strongest spirit, but the alcohol is more completely separated from the less volatile oils which accompany it. Derosne's apparatus, shown in Fig. 469, is extensively used in France for the preparation of brandy from wine. It consists of two stills, A and B, a distillatory column and fi^'^t rectifier C, a heater and second rectifier £, a condenser F, a vessel G, which by means of the float g regulates the supply of wine contained in the tank H. The principle of the whole method consists in bringing the wine by an uninterrupted descent into coLtinuous contact with the vapour as it ascends. The liquid and vapour are in actual contact throughout the greater part of the apparatus. The liquid is thus deprived of spirit, while the strength of Fio. 468. the spirit is increased. The wine which is ultimately distilled is thus sub- stituted for the water used in the old system of condensation. The wine flows from H to the vessel G, in which it is always retained at the same level by means of the float g ; a, small stream regulated by the cock w flows con- stantly into the funnel k, and enters the cooler F at A' ; the portion that has already been warmed by contact with the worm rises in the tube gg to the heater E, where it is discharged through a perforated gutter on to the hinder part of the coil of pipe s s. The wine is thus again heated in cooling the coil through which alcohol vapour is passing and condensing, and acquires almost a boiling temperature before escaping through the pipe hh to the rectifier C. In order that the wine may acquire as high a temperature as possible in F, a diaphragm is inserted at o, which separates the vessel into two compart- ments communicating with each other at the lowest part only, so that the wine which flows out through the pipe h has previously been in contact with the hottest coils of the condenser s s. Arriving at C, it falls in cascades over a series of lenticular discs of metal which retard its descent and allow time for the rectification to be efiected. The residue from the rectification called deeosne's still. 599 vinasse, which collects almost exhausted in the still B, is run off into A through the pipe d, where it is boiled, and after losing the last portion of alcohol is discharged at a. During the distillation, B is filled only to ^th of its depth, and A to |ths, the levels being indicated by the gauges p and p'. Fio. 469. Both stills are placed over one fire, so that the effect of the steam in B is heightened by the direct influence of the fire. The vinasse in A furnishes steam for the whole process, which, with a trace of alcohol, rises in the steam-pipe ff, and passing through the liquid in B, heats it to the boiling point. The vapour rising from B ascends into 6oo COFFEY S STILL. C, where it meets the descending rain of heated wine, from which it extracts nearly the whole of the alcohol, and is partly rectified by contact with the outside of Q. In D it meets the liquid which has been condensed by the action of the wine on the coil s « in the vessel E. This is allowed to collect on several shallow stages, and through it the vapour has to force its way under the little caps shown in the drawing, before arriving, at the coil ss. The liquid from these stages ultimately descends into the first vessel G. The last rectification is effected in s s, and the brandy then passes off to the condenser jP, through the worm zz. A quantity of more or less impure spirit collects in the lower parts of the coil s«, which is conducted away by the short pipes i i i to a common pipe v v, whence it can be let off either into D to be rectified, or may be mixed with the distillate by the pipe t. Coffey's still was patented in 1832. In principle, it is essentially the same as that of Derosne, but being intended to work mashed liquors, a separate boiler is employed to avoid the danger of burning. Fig. 470 represents this form of apparatus. Coffey's still as formerly Fig. 470. made resembled" externally a large wooden chest, being constructed of very thick planks covered on 'the inside with sheet-copper. Modern forms, how- ever, are composed of two tall, thin, rectangular towers, sometimes constructed entirely of copper, but still often with wood outside, the large chest or wash collector having been abolished. It consisted of a wash collector AAA and two upright quadrangular columns. The one D D D is called the anali/ser, and is intended for rectifying the wash; the other E B E, the rectifier, answers the purpose of a heater and dephlegmator ; the lower part F F F Siding as a rectifier for the feints, whilst the upper part condenses the alcoholic vapour. The distillation is efiected on the same principle as in Derosne's appa- ratus, a constant current of spirituous vapour ascending in one direction. COFFEY S STILL 60I being brought into intimate contact with a stream of wash descending in the other. The wash collector A is separated into two compartments; B and C, by a plate of copper c c. The plate c c is perforated with holes in the form of a sieve, and is furnished with T-shaped valves ooo. The analyser D is sepa- rated by similar plates r r and valves into twelve chambers ; and the lower part of the rectifier J?" i'' contains ten chambers similarly separated from each other by the plates s s s. The orifices in these plates permit the vapour to pass through them, but are too small for the descent of the liquid wash, which finds its way from one chamber to the other by the short pipes d and V. When the pressure of vapour is great, the valves o o allow it to escape. A constant stream of wash is drawn from G by the pump k into the pipe i, which supplies the entire apparatus. The supply is regulated by allowing the excess drawn up by the pump to flow back into the cistern H by the cock x through the pipe I. The pipe i enters the upper compartment of E, where it is separated into three branches, each of which traverses by a series of bends, only one of which is shown in the drawing, the entire height of the rectifying column E E and F F, passing from the last compartment but one by the pipe i to the uppermost compartment of the analyser D D. In the analyser, the wash flows from chamber to chamber, and arrives at length in C by the pipe d, whence it is let down at intervals into B by raising the valve h. This is done when the gauge at y shows that the chamber c is quite filled with liquid. It is essential that a stratum of liquid about an inch in depth should be allowed to rest on the plates r r, and the short pipes v are consequently allowed to project about that much above the level of the plate, while their lower extremities dip into shallow cups which remain filled with liquid and prevent the escape of vapour through them. In B, the nearly exhausted wash meets the current of vapour issuing from a boiler through a a, and the last trace of spirit is separated from it and carried with the vapour through the sieve apertures of the plate c c ; it thus passes through the entire mass of liquid in C, which it nearly exhausts of alcohol, and arrives through e in the lowest compartment of the analyser ; here it ascends through the wash collected in each compartment, becoming cooler in its progress, acquiring alcohol and losing water, until it is trans- mitted by the pipe m m to the lowest chamber of the rectifier. In F, it tra- verses the plates « s in a simUar manner, passing through the feints which have collected upon them in inch-thick layers by the rectification in E.. These feints are returned by the pipe ^ g^ to the cistern G, and pumped up again with the fresh wash. The vapour, arriving in E by the wide aper- ture u is compelled by the plates w w, which are not perforated, to follow the windings of the pipe i in its entire length, by which means it is condensed, and the wash flowing through the pipes is heated. The condensed vapour collects on the bottom of E, and is conveyed by pipes at p, not shown in the drawing, to another condenser. A plan similar to this has been adopted by Hill' for distilKng gas-liqiior, and will be described elsewhere. The modern form of Coffey's still, and the general arrangement of plant used in connection with it are shown in Figs. 471, 472, 473, which are from plans supplied by Messrs. Blair, Campbell, and McLean, of Scotland Street Copper Works, Glasgow. Fig. 47 1 shows the analyser and rectifier columns in elevation and in vertical section; Fig. 472 shows the general arrangement of boilers, pipes, receivers, pumps, and other plant, in eleva- tion ; and Fig. 473 is a ground plan of the whole arrangement, showing the position of all parts of the apparatus. The following reference letters apply to all the illustrations : — 602 MODERN FORM OF COFFEY'S STILL. A is the analyser column ; b, the boilers ; c, the cast-iron condensing tank ; D, the copper wash^pipes ; E, the steam stop-valve ; f, the copper dip^pipes ; G, the copper pans ; h, the copper vapour-pipe ; i, the position of pumps and MODERN FORM OF COFFEY'S STILL. 603 604 MODEEN ARRANGEMENT OF COFFEY'S APPARATUS. ACTION OF COKFEY'S STILL. 60$ engine ; J, the hot feints receiver ; k, the copper spirit-worm ; l, the copper feints-worm ; m, the copper condensing- worm : n, the copper division-plates; o, the brass valves ; p, the copper perforated steam-pipe ; q, the manhole doors ; b, the rectifier column. The method of working this modern plant is as follows : — When commencing an operation, the wash-pump is set in motion, to charge all the zigzag pipes, until the wash passes over into the analysers. The pump is then stopped, and the steam let into the bottom of the apparatus. The steam passes up through the chambers and bj' the pipe into the analysers, whence it descends through to the bottom of the rectifier. It then rises through the chambers enveloping the zigzag pipes, and rapidly heats the wash contained in them. When the attendant perceives, by feeling the bends, that the wash has been heated in several layers of these pipes — perhaps eight or ten layers, but the number is not of much moment — he again sets the pump to work, and the wash, now boiling hot, or nearly so, and always in rapid motion, flows from the pipe, and passes down from chamber to chamber through the dropping pipes. No portion of the wash passes through the small holes perforated in the diaphragms which separate the chambers. These holes are regulated both in number and size, so as ■not to be more than sufficient to afford a passage for the vapour upwards, under some pressure. The holes, consequently, afford no outlet for the liquor, which can only find its way down in the zigzag course. It is obvious, therefore, that the wash, as it passes down, is spread into strata as ■ many times as there are diaphragms, and is thus thoroughly exposed to the action of the steam constantly blowing . up through it. As it falls froni chamber to chamber, the alcohol in it is volatilized by the steam passing upwards ; and, by the time the wash has reached the large chamber, no trace of spirit remains in it. The wash, as it descends from the analyser, accumulates in the large chamber until it becomes nearly filled, when the attendant opens the valve and discharges the contents into the lower com- partment; then, shutting the valve, the wash from the analyser again accumulates ; and when it is nearly full, the contents of the lower chamber are discharged from the apparatus altogether, through the cock, and when it is empty the charge is let down from the upper chamber by opening the valve as before ; thus the process goes on, so long as there is any wash to supply the pump. When the wash is gone, a quantity of water is let into the reservoir and pumped through the pipes, to finish the process and obtain the last portions ■ of alcohol. This winding up of the operation, by sending water through the pipes, takes place on the distillation of every " back " of wash, in conse- quence of the Excise regulation, which requires the distiller to keep the produce of each " back " separate from that of any other. Were it not for this regulation, the distillation would go on uninterruptedly so long as there was any wash in stock ; the addition of water for winding up would be necessary but once during the distilling period, and the manufacturer would save much time and fuel at present wasted by these interruptions. It has been already said that, in the ordinary course of the operation, the wash is stripped of all its alcohol by the time it has reached the bottom of the analyser ; but, as a precautionary measure, chambers have been added, in each of which the spent wash is exposed for about half-an-hour to the action of the steam blowing through it. There is a small apparatus, by which a portion of the steam from the chamber is condensed, cooled, and made to flow constantly through a sample jar in which is an hydrometer, or, what is better, two glass bulbs, one of the sp. gr. i.oo, and the other o.ggS. When the lighter of these bulbs floats in the sample, it is all right, and the chamber may be emptied without any risk of loss. 6o6 MODE OF WORKING COFFEY.'S STILL. The course of the wash being uuderstood, that of. the steam will require very little description. The steam, as it rises, is first blown through the charges of spent wash in the lower chamber ; thence it passes up through the layers of wash on the eleven diaphragms of the analyser. In its course, it abstracts from these layers of wash their alcohol, depositing in its place an equivalent of water. After traversing the whole of the analyser, the vapour, now containing much alcohol, passes by the pipe into the bottom of the rectifier, and, as it ascends, it envelops the pipes heatiiig the wash, and simultaneously parting with its more watery portion, which is condensed, and falls in a state of ebullition on the several diaphragms of the rectifier. By the time the vapour reaches the passage in the bottom of the finished spirit condenser, it is nearly pure alcohol ; and as it is condensed by the wash in the pipes, and falls on the diaphragm, it is conveyed away by the pipe to a refrigerator. At the top of the spirit condenser is a large pipe, which serves as a vent for the incondensable gas which is disengaged in the process, and this pipe also communicates with the refrigerator ; so that, should vapour at any time pass out of the apparatus, no loss is sustained beyond the waste of fuel caused by condensing that vapour by the water of the refrigerator, instead of by the wash of the condenser. The liquor formed on the several diaphragms of the rectifier, after the vapour, passing up from plale to plate, has , blown through it, desceiids to the bottom in the same mannor as the wash falls from chamber to cham- ber in the analyser ; but this condensed liquor stUl contains a portion of alcohol, and it is conveyed by the pipe to the pump by which it is raised up with the wash to be again distilled. • A thermometer shows the temperature of the wash as it issues from the pipe into the analyser, which is the only guide required for managing the operation, for, when the temperature is what it should be, nothing can go wrong in the work. Whenever the thermometer indicates too high a temperature, more wash should be let into the apparatus, and vice versd — the quantity being regulated by the tap and the pipe. It would seem, however, that very little nicety is requisite on this point. Experience has proved that the fluctuation of a few degrees above or below the proper heat is of little consequence, and that it is very seldom found necessary to alter the supply of wash. The water for suppljring the boiler passes through a long coil of pipe im- mersed in boiling spent wash, by which means it is raised to a high tem- perature before it reaches the boiler. It will be seen that the vapour passing through this apparatus is also condensed by the wash, not by water, and therefore no heat is wasted, as in the ordinary process of distillation. The consequence of this is that about three-fourths of the fuel used with the common stills is saved, a matter of very great importance. According to the ordinary process, it requires twelve pounds of coal to distil a gallon of proof spirits ; btit when coals of a superior quality are employed, and the stills are properly constructed, less will suffice. Of the twelve pounds referred to, nine pounds are saved by the new system ; and, assuming the whole quantity of spirits distilled in the empire to be 36,000,000 gallons (which, with the Colonies included, is not over the mark), the saving of fuel arising from the new methods of distilling, if universally adopted, will amount to 140,000 tons of coal per annum. One of Mr. Gofiey's stills at Inverkeithing works off two thousand gal- lons of wash per hour, and one, which the inventor subsequently erected at Leith for the same proprietors, upwards of three thousand gallons. There are several of equal magnitude, and it is stated that those now at work, or being erected, are capable of distilling half a million gallons of wash per day, this wash yielding, on an average, from 11 to 12 per cent, of proof spirit. DESTRUCTIVE DISTILLATION. 607 Several of the metals which are volatile at a high temperature are sepa- rated from their ores and purified by distillation. Fig. 474 shows the Fig. 474. Fio. 475. distillatory furnace employed at Idria for obtaining mer- cury from the sulphide. The ore is placed in large pieces upon the perforated arch nre' immediately above the furnace ; the arch jo jo' is covered with smaller pieces, and above r r' the powdered mineral and the residues from former operations are placed in small earthenware dishes. A powerful fire is made under the lowest arch, the flame and products from which pass through the several layers of mineral, while currents of air from the channels H, G, penetrate the walls of the kUn and oxidize the sulphur which is in combination with the mercury. The metal thus liberated passes over in the form of vapour by the flues « s' and is condensed in a aeries-of -chambers GG C. Destructive DistiU^tion. — The distillation of sub8ta];xces which are decomposed in the proems', is carried on to a great extent for the sake of the products. Sometimes the residue which is left after the removal of the volatile pro- ducts is the aim of the operation. This is the case with all the processes of char- ring which have been described in the pre- vious pages, and where in many in- stances the volatile products are not col- lected. When the volatile products have sufficient commercial value to repay the cost of condensing apparatus, the opera- tion of charring is conducted in close vessels, and becomes a process of dry or destructive distilla- tion. The nature of the substance, the mode of conducting the operation, and the character of the products vary so much in these processes, that no general rules can be laid down for the construction of apparatus, which must therefore be looked for in other divisions of this work, where the seve- ral branches of manufacture involving dry distillation are described. eo8 DESTEUCTIVE DISTILLATION OF WOOD. Fig. 475 (p. 607) represents a system adopted for distilling wood for the production of tar, pyroxylic spirit, and wood-vinegar, ra is a strong wrought- iron box with an air-tight lid b set over a fire at c, the flames from which circulate round the sides of the box in the flues ddd, escaping at e to the chimney. The products of distillation pass oflF by the pipe/, which is sur- rounded by a wider pipe hh in several of its bends, through which a current of cold water is flowing in the opposite direction to the volatile products in the inner pipe. Cold water is supplied at i, and passing from one pipe to Fig. 476. the other by the connecting pieces k, passes off at /. The gaseous products of distillation, which are valueless as illuminatipg agents, are conducted to the fire by the cock o, where they develop considerable heat in burning, whilst the condensed products are collected for purification in the vessels m. In this arrangement, the process must be interrupted with every fresh charge of material in the box a. Fig. 476 represents the close retorts invented by Halliday for the dis- tillation ef refuse sawdust, tan, dye-woods, and other ligneous matters which are necessarily in the state of coarse fragments or powder. The process of distillation is continuous, a constant supply of material being FiG. 477. introduced by means of a screw into the front part of the retorts, and the residuary charcoal dis- charged in a similar manner. The retorts are in the form of cast-iron cylinders arranged over fur- naces in a manner similar to that adopted in gas works, the screws by which the material is made to travel from the front to the back of the retort being of nearly the same diameter as the retort itself. Each retort is furnished with a wide pipe at the back, the lower extremity of which dips below the surface of water contained in a tank into which the charcoal falls, whilst another pipe carries away the volatile products to a condenser. An oven for charring peat and collecting the volatile products (Fig. 477) was erected at Courcy- sur-Ourcq, near Meaux. It consisted of a cylin- drical retort a, heated by the flues h; and in order to maintain the temperature as uniform as possible, there were open spaces d left in the wall, filled with air. The flames ascended from the fire- places c, and the smoke passed off through an opening in the metal plate g on the top. The peat was thrown in at e, and when full the retort was closed by a strong cast-iron plate/, which was covered with sand and ashes, HEATING GAS KETOETS. 609 over which the smoke from the fire passed. The gaseous products escaped by a pipe I to the condenser, and when the operation was finished the char- coal was drawn out into a pit k through the bottom of the retort, which consisted of an iron damper h, movable from the outside. Heated steam has been proposed as the source of heat in certain pro- Fio. 478. cesses of destructive distillation. Thus, for distilling turf or peat, the apparatus sketched in Fig. 478 was patented by Vignoles. The steam generated in the boiler a is heated to a high temperature by passing through a ^^^ series of pipes H, which are placed in a separate fur- nace, and is con- veyed to a number of cylindrical vessels containing the peat, which are also heated by the waste heat from the boiler furnace. The vola- tile products from the peat are carried away by the steam and condensed in suitable apparatus, whilst the charcoal is discharged from the bottom of- the cylinders into trucks placed below them. Heating Gas Ketorts. — An economical arrange- ment for distilling coal for the manu- facture of gas is shown in Figs. 479 and 480. CCC represent seven cylindrical clay retorts ar- ranged round the common furnace A. These receive the direct heat from the fire ; the hot gases, passing by flues in a downward direction, as indicated by the an-ows, R R ■ 6io HEATING (JAS EETOETS BY GAS. Fig. 480, subsequently heat five cast-iron retorts BBB situated below the furnace, before escaping to the chimney by the flue E. The volatile pro- ducts of the distilla- ^'•*- 480- tion escape by the pipes shown in Fig. 497 from the necks of the retorts to a main where the tar, and other condens- able products, are partially collected ; and they are sub- sequently passed through extensive condensers to sepa- rate the liquid pro- ducts completely from the gases. It is not surpris- ing that the heating of the retorts in gas works should have been recognized at an early date as an important field for the application of gas firing. Mr. Charles Hunt,* in a paper on this subject in February 1884, said that "heating gas retorts by fuel in the gaseous form, as a substitute for its common applica- tion in the solid state, dates almost as far back as the introduction of the regenerative system by the late Sir "William Siemens, more than twenty years Fig. 481. ago The success that attended the latter in its application to other indus- tries led to its being applied Experimentally in at least two gas works m this • "Jour. Soc. Chem. lud.," vol. iii. 1884, p. 89. HEATING GAS RETORTS BY GAS. 6ii Fia. 482. country — namel}', the Brick Lane Station of the then Chartered Gas Com- pany, and the Windsor Street Works, at that time belonging to the late Bir- mingham Gashght and Coke Company. In neither case, however, were the results such as to secure for it a more extended use, although almost simul- taneously it obtained a firm and (as it proved) enduring footing at the works of the Paris Gas Company, where, with sundry modifications of detail, it has ever since been very largely employed. Figs. 481 and 482 show substantially the arrangement which, down to the year 1875 (when it was finally abandoned), was used in Birmingham for heating six beds of retorts. It is that of the familiar alternating system, with regenerators for both gas and air, worked by means of reversing valves, the producers (not shown in the figure) being of the ordinary kind with sloping grates, placed at a convenient distance outside the retort house, to which the gas was conveyed by the usual wrought-iron condensing tubes." These figures also give the main features of the plan originally introduced into the Paris Gas Works, but not the modi- fications which were subsequently introduced. In the opinion of Mr. C. Hunt this system was un- successful in Britain on account of its greater com- plexity, uncertainty of action, and first cost, as compared with the simple and convenient, although more wasteful, method of direct firing with solid fuel. In view of the progress which has been made in this matter since these early days, it appears that success has mainly depended upon having con- tinuous regeneration of heat and an arrangement of retort benches with the gas producers in immediate proximity to the charging doors, so that a large portion of the initial heat of the coke should be transferred to the producers by charging them with the hot coke from the retorts. An early form of retort heating gas furnace — perhaps the earliest form introduced — having this arrangement, was that of MM. Oichelhauser, Miiller, and Eichelbrenner, employed in the gas works at Montreuil.* It is illustrated by Figs. 483-486, as applied to heating a pair of groups of seven retorts each placed side by side, the gas producer being at the back of the retort bench in the centre. This producer or " shaft '' is shown in section at A on Fig. 483, and on plan in Fig. 484. B is a step grate for admission of air, and to prevent the coke falling out ; the carbonic oxide formed in the producer being led away by the opening h (in Figs. 483 and 484) from which it passed by r (Fig. 484) to S (Fig. 485), a channel placed in the axis of the retort setting at the bottom. From the top surface of S, a series of openings led the gas into the furnacfe, where it met the air for combustion * See " Gas Engiueers' Diary, &o.," 1882, p. §3 , Etudes sur la Combmtion, by M. Fichet, Mem. de la Soc. (les Ingin. civtls, 1874, p. 670 ; " f iiel, Us Uombustiou and Economy," Williams and Clark, p. 242. R B 2 Fjg. 483. 6l2 MULLEE AND EICHELBEENNERS SYSTEM. from two passages a (Fig. 484) placed alongside S, the air having previously been heated by traversing passages in the setting which were heated by conduction. This arrangement has been very successful, having in one form used, as fuel for the distilling operation, 17^ per cent, in the shape of Fia. 484. coke of the weight of coal distilled, a single furnace with ordinaiy grate holding the same number of retorts having previously consumed coke amounting to from 30 to 35 per cent, of the weight of the coal distilled. In the latest form it is said that one generator serves for two benches of eight retorts each, and is charged every six hours, the average production „ g of gas in twenty-four hours ■ * ^' from eight retorts being 65,000 cubic feet, and the consumption of fuel for every hundredweight of coal car- bonized being 16 lbs. Mr. Gr. E. Stevenson has remarked* that the first gene- rators applied to gas retorts in Germany were those of Didier, Hasse, and Liegel, " In the two first " of these, he says, " success was not obtained because the destruc- tion of the Kning of the gene- rators was too great. The furnaces had large horizontal openings at the bottom on the level of the hearth, and the fire-clay lumps surrounding these openings were quickly destroyed." Liegel claimed to treat successfully the clinker, on the system of melting it and running it out at the bottom of the furnace, "by so constructing his furnace that the partially melted clinker remained as a thin stratum, covering and protecting the brickwork, and the super- fluous clinker escaped from a narrow slot at the bottom of the furnace,, falling directly down into an ash-pit, and not Uke the Didier, remaining on a hearth in proximity to the furnace sides until drawn out by rakes." The system of dealing with the residue on- the plan of preventing the formation * "Miti. Proc. Tnst. C. E.," vol. Ixxxiv. p. 98. didiee's, liegel's, and othee systems. 613 of clinker, and reducing the residue to a soft ash to facilitate its removal, was originated by Dr. Schilling, assisted by Dr. Bunte, at the Munich Gas Works. These inventors placed a flat pan or tank containing water beneath the grate of the generator, and evaporated the water by conducting the waste gases under the pan after they had left the regenerator. In one arrangement of Dr. Schilling's system, a steam-pipe is shown which is led under the grate of the generator. In Klbnne's arrangement also, water is Fio. 486. used under the generator grate, and the Siemens generator at Glasgow has been modified to the extent of having external jets of steam directed upon the incandescent coke at the openings for air at the level of the hearth.* In the WUson producer, as arranged for this purpose, steam and air are delivered together in the interior of the producer at the centre of the hearth. The main object, according to Mr. Stevenson, in the application of gaseous firing to retorts is the adaptation of a suitable system of regene- ration which combines efficiency with economy in the construction, and does not occupy an unnecessary amount of space. For the latter reason, the Fig. 487. Fio. 488. regenerating flues in all the systems hitherto adopted have been placed below the retort setting on either side of the furnace. There is no reason, however, why, in small gas works especially, a serviceable plant should not be obtained for a small outlay on the plan of having iron-pipe regenerators * See "N.B. Assoc, of Gas Manaprera " 1882. 6i4 liegel's and valon's systems. placed above the retort setting, as was proposed by Mr. Wilson to the N.B. Assoc, of Gas Managers (1881). Fio. 489. Fio. 49°- The Dessau or Didier generator, as vised at Dresden, is shown in Figs. 487, 488. Liegel's arrangement is illustrated by Figs. 489, 490, these figures Fig. 491. Fig. 492. ^^ SCHILLINGS SYSTEM. 615 Fig. 493 having the modifications of the original Liegel arrangement which were proposed by Mr. G. E. Stevenson. In Li&gel's plan, shown in the Gaa Engineers' Diary and Text Book for 1882 (p. 97), the generator is placed almost entirely under the retorts with a fiew to utilize the heat radiated from this portion of the appara- tus. Liegel's plan is understood to have been the first constructed with what is called a " slit " generator — i.e., " a generator terminating in a long narrow slit for the admission of the primary air-supply " — and is also said by Mr. C. Hunt* to have been " the prototype of the first generator furnace con- structed in England at the Old Kent Boad Gas Works by the then engineer, Mr. G. Livesey.t This latter arrangement is said to have been improved by Mr. "W. A. Valon, of Ramsgate,| whose plan is illustrated by Figs. 491, 492. Mr. Valon aimed at simplicity in construc- tion and lessened first cost, but apparently at the expense of the size of the regenerator flues, although he maintained that he obtained results which were as good as those obtained with more costly arrangements. As regards the extent of regenerating surface provided by the various systems, Mr. Stevenson remarks that "the systems of Schilling and Klonne possess the most complete re- generation, and give the most economical results as regards the consumption of fuel, while that of Liegel is less expensive, and gives a high heating power, but uses a somewhat greater proportion of fuel." Dr. Schilling's system is shown in Figs. 493 and 494, this being its form as improved by the inventor and Dr. Bunte, and described in the Journal fur Gaabdeuchtung, where it is said of it that it consumes only 14 lbs. of fuel per 100 lbs. of coal carbonized. Klonne's arrangement, which has been erected at Birmingham Gas Woi'ks and in Scotland, has found favour in this country on account of " its superior adaptability," according to the opinion of Mr. C. Hunt. Figs. 495, 496, illustrate the arrangement as devised by Herr Klonne, and Figs. 497, 498, show the system as modified by Mr. Hunt, and erected by liim at the Windsor Street Gas Works in Birmingham. The Siemens plan, as finally adopted at the Glasgow § Gas Works, ia • "Jour. Soc. Chem. Ind.,"' 1884, P- 92- t See Mr. F. Livesey, Brit. Assoc. Gas Managers, London Meeting, 1880, " Jour, of Gaa lighting," 1880. X See "Jour, of Gas Lighting," vol. xli. pp. 269-270. 5 See "Jour, of Gas Lighting," vol. xli,. p. 1139 ; '-Jour. Soc. Chem. Inri.," 1884, pp. 92-94; " Engineering," Jan. 19, 1883 ; " froc. N.B. Assoc. Gas Managers," Feb. 18S4. 6l6 SCHILLING'S AND KLONNE'S SYSTEMS. shown in Figs. 499, 500, this plan having been arrived at by increasing the height of the generator relatively to its diameter, introducing jete of Fio. 494. steam, which were absent from the original plan, and abolishing regenerator flues constructed of iron or steel plates in favour of fire-brick passages. Fio. 495. Fis. 496. \ Finally, Figs. 501, 502 (pp. 618 and 619), show the plan with iron-pipe regenerators proposed by Mr. Alfred Wilson,* who remarked, " as regards the * " Proo. N.B. Assoc?, of Gas Managers," July 1881 ; " Jour, of Gas ligbting," 1881. STEVENSON'S AND SIEMENS' SYSTEMS. 617 durability of a cast-iron pipe regenerator," that the " experience gained with the hot-blast stoves of iron-smelting furnaces over many years has proved, first, that of all forms of wrought or cast iron the most durable is a cast-iron pipe, either cylindrical or oval, and of moderate dimensions as regards cross- Fio. 497. Fig. 498. sectional area ; secondly, that heating stoves composed of cast-iron pipes will stand from five to ten years subjected to a temperature which heats the air passing through them to 1000° F." Distillation is sometimes carried on in a vacuum, when apparatus Fjg. 499. Fio. 500. similar in principle to that described under Evaporation is employed, proper measures being taken to condense and collect the vapour ; and this has been applied in a modified way to the manufacture of coal-gas. When the substances to be distilled require a very high temperature, which metal vessels are unable to withstand, fire-brick ovens are employed. 6i8 WILSON'S SYSTEM— DRYING. This IS the case with pitch, which is distilled in the ovens shown in Fig. 503; a full' description of which will be given in another volume. The f urnace^ and flues are below the ovens, the smoke passing by an underground flue to the chimney. The cast-iron pipe through which the volatile products escape is shown at the top of one of the ovens. , , Drying. — The removal of the last portions of moisture from manu- factured goods is an operation necessJarily connected with the application of fuel, in all those countries at least where the climate is changeable, and Fio. 501. simple exposure to the. air and sun cannot be resorted to, or are insufficient for the purpose. Indeed, so irregular and uncertain is the system of open- air drying, thait it is not adapted for manufactures, where definite quantities of goods are produced every week throughout the year. A current of warm air is generally considered the most effective drying agent, the apparatus for heating the air being placed either outside the drying chamber, or in •WILSON'S SYSTEM — PITCH OVENS. Fig. 502. 619 Fig. 503. 620 USS OF FUEL IN DEYING. the interior. From the known quantity of aqueous vapour which air is capable of taking up at different temperatures, and the amount of moisture to be expelled in a given time, the quantity of air to be supplied in each special case can be calculated ; the size of the drying-chamber and the diameter of the vapour chimney being adapted to the size of the heating apparatus and the amount of fuel consumed. When the substances to be dried are of such a nature as to remain uninjured by the air which has passed through the fire, and is mixed with carbonic acid gas and more or less smoke and dust, the fire may be made below the drying chamber, and the products of combustion allowed to pass into it, care being taken to place the fire at a sufficient distance to prevent the danger of igniting the substances to be dried. Where smoke is prejudicial, anthracite or coke may be employed as fuel. In far the greater number of drying operations, however, the products of combustion, and the dust and ashes with which they are necessarily mingled, are highly injurious, and hot-air stoves, or pipes conveying steam or water, applied in the manner described in the foregoing pages, must be employed for heating the current of air. The drying-house should be constructed of badly conducting materials to prevent loss of heat by the walls, and contain Fio. 504. no permanent apertures but those for the entrance and exit of the air current, the doors for the introduction of the goods being securely closed during the operation. The size of the drying-room should be so pro- portioned to the work to be done, that the air at its exit is completely saturated with moisture, and the substances so arranged as to expose the greatest possible surface to the air current, whilst no air saturated with moisture is allowed to remain stagnant in any part of the chamber. From 7 to 10 feet is a convenient height for the chamber, and a very great advantage is gained by causing the hot-air current to enter at the upper part, and escape from the level of the floor. The velocity of the current is thus retarded, and time allowed for its perfect saturation, whilst partial currents and consequent stagnation in certain regions of the chamber are avoided, which almost invariably occur when the current passes rapidly in an upward direction. Several vapour chimneys for discharging the saturated air often produce a better distribution of the hot current than a single vent, and it is frequently necessary to cap them with a movable cowl, which, turning with the wind, allows the vapour to . escape more easily. The draught may often be secured and augmented by connecting the vapour discharger with the chimney of the heating apparatus. DRYING WOOD — MALT KILNS. 621 Fig. 504 shows a series of drying chambers employed for drying wood for the use of glass houses in France. The six chambers AAA are each 60 feet long, 6 feet broad, by 5 feet high ; they are arched over, and the whole of them covered by a single roof. There is a fire at each end of every chamber, and the products of combustion are allowed to enter by the passages g g into the body of the kilns at some distance from the grates. The wood to be dried is placed upon trucks, which travel on the rails a a. The system usually practised by bleachers and others in this country for drying their goods, is by an intermittent saturation of the air contained in the dr3dng chamber. The chamber is built over a furnace, the metal flue from which extends through its entire length. The goods being introduced. Fig. 505. the chamber is kept carefully closed until the air has become saturated with moisture, which may be observed by a window in the side becoming dis- tinctly covered with dew. The door and louvres or shutters in the top are then opened, when the moist air is discharged, and a fresh supply admitted. This operation is repeated until the goods are sufficiently dry. Although this is a very simple method, it not only involves a considerable loss of heat, but the goods are only imperfectly dried. Kilns are employed for drying malt, into which the products of com- bustion from a charcoal, coke, or anthracite fire are carried, with a large body of warm air, through a perforated metal floor, upon which the malt is lightly spread out. The modern form of malt-kiln arranged with a gas fire 622 MALT KILNS. is shown in Figs. 505, 506. Soilietimes a current of warm air only is em- ployed, while the smoke and heated gases from the fuel are removed by a Fio. 506. F18. 507. flue. This arrangement of the malt-kiln may be seen from Fig. 507, where the air, heated by the stove, ascends through the perforations in the floor above it, upon which the malt is placed. In the large breweiies of Bavaria the malt is dried in the manner shown in Fig. 508, by warm air. A is the fire for heating the dry- ing floor, which is often assisted by the waste heat from the boiling-furnaces supplied through B. The iron cylinder which conveys the smoke and heated gases from the fire, communicates with the triangular horizontal metal flue g gg, passing in a zigzag manner under the wire-gauze floor m m, upon which the malt is placed. After circulating in this flue, the smoke escapes through the chimney at B. The dampers x and x' in the flue B enable the smoke from the boiling^furnaces to be carried either directly to the chimney or through the flue G to the malting-floor. BAVARIAN MALT KILN. 623 Air enters tHe flue h b which surrounds the smoke-pipe a, and is conducted by a series of balfTopen . channels, constructed with bricks, on the floor of the drying-chamber, below the horizontal flue g g. These channels are higher on the one side, and are covered with tiles in a slanting direction, to prevent any particles of malt from falling into them. The air thus warmed by contact with the smoke-flue, passes through the malt and dries it. The wire-gauze bottom, over which the malt is spread out, is supported by bars of iron. Fig. 508. The methods of drying manufactured goods by exposure to the radiant :heat of the surfaces of channels through which smoke or steam is passing, and. the centrifugal application now so universally employed, involve no novel application of fuel. Baking, Annealing, Calcining, &c. — Ovens and kilns are used for a gCffltt variety of purposes in the arts, and are modified in form and con- struction to suit the different objects in view. 624 OVENS FOR BAKING BREAD. In some opei'ations, it is necessary carefully to separate the objects to be baked or heated from the fuel and products of combustion ; while in others, the contact of these with the fuel and smoke is attended with little or no inconvenience, and sometimes is even absolutely necessary. Most of these operations differ from simple processes of drying, by the change of Pio. 509. FiQ. 510. cl emical composition which the high temperature employed induces in the objects exposed to it. The ovens employed for baking bread are still very commonly heated by wood, which is placed upon the sole of the oven itself, flues being introduced at the back for carrying away the smoke. When the charge of wood is completely consumed, these flues are stopped by dampers, and the ashes are removed. The bread is then intro- duced, and the oven closed, the accumulated heat in the brickwork being sufficient to bake the bread. The opera- tion is in this case neces- sarily interrupted each time a baking is completed, and coal should not be employed as fuel, on account of" the dirt it produces, although the flame from a coal fire is still often admitted to heat the oven. Figs. 509 and 510 show sections of a large oven, in which the fuel is not admitted into the interior, and which admits of an uninterrupted process. Coal is burnt on the grates at n n, and the smoke and heated gases from its combustion passing through a series of arched flues below the sole of the oven a a, return again by the flue b over the top to the chimney y. In the front of the oven, which is less exposed, distinct flues convey a portion of the flame into the oven, or over it, as may be required, while a series of pipes in connection with the flues carry off the vapour rising from the loaves in baking. PORCELAIN KILN. 625 In baking porcelain and pottery, a very high temperature is required, •while the objects exposed to it must be carefully protected from the smoke "and dust of the fuel. Figs. 511 and 512 show the construction of a porcelain kUn. Four separate fires, 4 ^ 4 ^, discharge the flame and products of combustion into the body of the kiln L L', in which the goods are carefully packed in Fig. 511. protecting vessels called seggars. The fires have no grates, but, the space e being filled with red-hot charcoal, wood is introduced through the aperture ft', until the eiitire space /is filled with fuel. Air is supplied through ft' in the downward direction indicated by the arrow, and has therefore to pass through a great body of ignited fuel before reaching the body of the kiln ; cold air is thus excluded, and more perfect combustion secured. The flame is separated into three distinct portions, passing through the flues ppp. s s 626 STONEWARE KILN. Fig. si 2. The diflerent stages in the kiln L L' and G are connected by numerous apertures ttt. In the lowest, where the greatest heat prevails, the final baking of the ware is effected ; whilst the upper stories are used in the earlier parts of the process of manu- facture. ^ig- 513 represents a kiln em- ployed for baking stoneware in the Lambeth potteries. Coal being the fuel consumed, a slanting grate, shown at c, is employed, which is fed from above in such a manner that the air is forced to pass through and over the burning fuel. Five of these grates are placed at equal distances round the body of the kiln, a per- forated chimney, or hag, of brick- work, being placed opposite each fire to separate the flame at its entrance to the kiln. Gas-fired Kilns. — The problem of applying gas firing to kilns for burning fire- and other bricks, and probably for pottery also, has been solved in a practical way very suc- cessfully by the patent degenerative kilns of Mr. James Dunnachie.* • See paper by John Mayer, F.O.S., " TraDS. Inst. Engin. and Shipbuilders in Scotland," vol. for 1885. dunnachie's gas kiln. 627 Formerly, the large amount of heat absorbed by bricks and pottery in the process of burning was uselessly dissipated during the cooling of the kilns and their contents, but in the Dunnachie kiln it is used to heat up the air Fio. 514. ^N\ . .*. ..9: c::jii;::!dzm::^^i^^?^ I'" Ground Plan. required for combustion of the gas, and thus a chamber of burned bricks or ware serves the same purpose, and has exactly the same function, as a regenerator chamber in a Siemens furnace. 5'5- Figs. 514-517 illus- trate this kiln, which consists of a series of chambers placed side by side. Fig. 517 is a longitudinal vertical section through one set of five chambers. The gas, which in the , -^ , case of all the kilns (BjJ first introduced and worked on this system. Cross Section, was supplied under a positive pressure from " Wilson '' producers, is admitted through the flue A, and passes into the burner B, where it meets with the hot air Fio. 516. OIBllEB FOB from the adjoin ing chamber entering by the flue F. From the flue C; the draught may be passed on, either into the next , . chamb,6r, or to the chimney, as may be desired. By this arrangement, the waste heat is utilized in the unburned chambers in advance, which are thus s s 2 Front EleTation. 62S GAS-FIEED POTTEEY MUFFLE. heated up preparatory to full firing, while the heat of the chamber which has been "burned off" is transferred by the air-supply traversing it to „ the pla«e of combus- Fi(i. 517. ,. *^ ^ ' - tion. The hot air and gas meet at the floor level, when there is ' Longitudinal Section. duced. Both air and gas, being governed by regulating valves, may be varied in quantity and proportion to the requirements of any special case. The flue Z> is provided in order to admit Fio. 518. -wrm air to any chamber at a higher level than that of the main supply from F, and is used either for exhausting the heat from the higher layers of bricks P^^ in a burned-off cham- ber, or for tempering (by the admission of cold air) the heat in a chamber which is being burned, so as ta prevent the front of the bricks being too much buimed. By means of these kilns, fire-bricks are burned at the Glen- brig Works more satisfactorily, and with a saving of 75 per cent, in fuel and ■JO per cent, in time as compared with coal- fired kilns. There is also a saving in labour and in the wear of the kilns. Figs. 518, 519, illustrate a kiln or muffle successfully used at Linthorpfr HOFFMANN'S KILN. 629 Pottery for glazing art pottery. In this case, continuous regenerators of cast iron, formed into a coil or stack of pipes^ were used, the air-supply being propelled through these pipes by a fan, and meeting the gas from the pro- ducers at one end of the oval combustion chambers placed under the mufHe. The flame and hot gases passed up on both sides of the mufile chambers and escaped by openings at the roof, whence they passed away by the flue in which the iron-pipe regenerator was placed. The only difficulty experienced in working this kiln was that of getting any material to stand the exceed- ingly high temperature of combustion produced by the blowpipe arrange- ment. Hoffmann's patent kiln was, if not the first, certainly the first successful method of utilizing some of the heat which in old-fashioned kilns is still uselessly wasted. Consequently, this kiln was economical in working. It was, however, worked with solid fuel charged through holes in the roof into Fio. 520. the fire-places, which were built in among the bricks being burned, and were arranged with openings to flues so that the draught and hot air could be taken in any desired direction. This kiln was, however, suitable only for red bricks. Figs. 520, 521 (which have been supplied by Mr. John Craven), illustrate this kiln arranged with twelve chambers set radially round a central chimney. Fig. 520 is in sectional elevation, and Fig. 521 in plan partly sectional. In order to put this kiln in operation, all its compartments are filled with green bricks, except one, which is left empty for the purpose of com- mencing the firing from below in the ordinary way by fires made in a brick wall temporarily built across the burning chamber in front of the bricks set in the kiln for burning. When these fires have caused the bricks in the first one or two compartments next to the temporary wall to become red hot, the firing is continued from above by dropping coal through the feeding- holes in the arch of the kiln. 630 METHOD OF WOEKING HOFFMANNS KILN. If, in setting a kiln to work, the temporary wall is built between cham- bers 12 and I, chamber 12 is left empty, a damper is built between chambers 11 and 12, and the setting of green bricks is begun in cham- ber II. When II is filled, its doorway is closed, but a small fire-hole is left in it at the floor level, where a tire is made to drive off" the moisture from the bricks, the valve of chamber 1 1 being opened to draw off the mois- ture with the smoke. Then chamber 10 is tilled with bricks, and its doorway closed in the same manner as that of chamber 1 1 ; a small fire is made in it, as in the former case, and its valve opened. In this way the filling of the chambers with bricks goes on in the direction opposite to that in which afterwards the fire will take its course, until at last chamber i is Fig. 521. filled with bricks, when the temporary brick wall already mentioned is built up in front of it across the kiln with as many fire-places as there are rows of feed-holes in the arch of the kiln. Small fires are lighted in these fire-places, and therefore no fire is required in the doorway of No. i. The firing in these fire-places is continued slowly for some days, so that the green bricks and the kiln walls are dried and gradually heated, when they can be exposed to an intense heat. The feeding-holes in the arch of the kiln are covered by caps, which are removed as long as steam or warm air is escaping by them, but must be replaced if air is drawn into the kiln through the holes. Before the fires in the temporary brick wall are increased, the small fires in the various doorways are allowed to go out, and the doorways are GUTHRIE'S GAS KILN. 63 1 entirely closed in succession, beginning with No. 2 and advancing towards No. II, the corresponding valves also being closed, at intervals of about twelve hours between each. The valves of chambers 10 and 11 remain open, so that the fire in the doorway of 1 1 burns longer than any of the others, and is not put out till the bricks in this chamber have become thoroughly warm. The fires in the brick wall in front of chamber i are now increased to the desired temperature. When the bricks in chambers i and 2 have become red hot, the firing from above through the feed-holes in the arch is commenced in these two chambers. The red heat advances from chamber 2 into chamber 3, and so on, the firing from above being commenced in each as soon as the fire-holes are red from top to bottom. When the firing has been commenced in chamber 3, the fires in the brick wall in front of chamber i are slackened, but small fires are kept up until the firing from above has advanced to chamber 4, when it is stopped in chamber i, and the fire-places in the wall are closed with bricks. At the same time one, and soon afterwards a few more feed-holes of chamber i are uncovered, to let the requisite air for combustion pass through them into the kiln. Firing from above has now been stopped in chamber 2, and the bricks in the two first chambers are now cooling off. In order to admit more air into the kiln, so that combustion may become more rapid, the temporary wall is gradually taken down, until, when cham- bers S and 6 are fired, the wall is altogether removed. As the heat ad- vances in the kUn, firing from above also advances with it, while at the same time it is discontinued in the rear in equal ratio, but always at a distance of about two chambers which are being fed with coal. When the firing commences in 7, the bricks in i are taken out, and chamber 12 is then filled with green bricks. The damper is now removed to between 1 2 and I, and the doorway of 12 is closed. When firing is commenced in 8, the burned bricks are similarly removed from 2, and chamber i is filled with green bricks, the damper being now placed between i and 2. This sequence is followed round the circle, one chamber being emptied of burned bricks and one filled with green bricks every day, care, however, being taken that the bricks in the last filled chamber are perfectly dry before the damper is removed.* Mr. Herbert Guthrie, C.E., also introduced a very interesting continu- ous Idln in which the waste heat was made use of. This, although called a " gas kiln," was not strictly gas fired, as there was a fire-place for solid fuel to each chamber. The waste gases were passed into a second chamber, so as to heat it up preparatory to full burning, and the waste heat in a burned- off chamber was made use of to heat the air, which was passed through the - fire of the one in advance. There is no doubt that a very strong heat would be thus economically produced, but the full advantage of gas firing could not be obtained by this plan in spite of its great ingenuity. A most interesting paper on its application to burning pottery was pub- lished by Mr. Guthrie in the Journal of the Society of Arts, vol. xxviii., February 20, 1880. Fig. 522 represents what Mr. Guthrie calls a sectional perspective of his kiln showing nearly every part of it. The chambers in which the goods are placed are indicated by the letter A, the gas producers by the letter G, the flue leading to the chimney by the letter i, and the wickets by the letter W. In making this arrangement, Mr Guthrie kept the following points in view : — First, that the form of the chambers should be no depar- ture from those in general use and proved to be of good shape and propor- * An improved chamber kiln fur bricks, lime, and cement, of the Hoffinaun type, called the "Hertrampf," is described in "Industries," November 12, 1886, pp. 512, i;i3. 632 gutheie's gas kiln. DJSTKIBUTION OF HEAT IN KILNS. 633 5i P 634 LIME KILNS. tion ; secondly, that the heat should rise from a similar position within those chambers ; and, thirdly, that the draught should take the same course through the goods. The modus opercmdi is this : The goods having been placed in several chambers and the wickets made up, fires are kindled in the gas producers, and the process of steaming, calcining, and burning carried on in much the same way as usual. Rather open fires are worked at first, with plenty of air, gradually making it hotter, and limiting the air as the successive stages are completed. At the beginning of the burning stage, however, the fires are made deep and close, working them like a gas producer instead of an open fire, and filling them up untU the fuel touches and perhaps rises slightly ajaove the sill of the air-port shown at the back of the producer in the division wall. By this means the amount of air can be regulated by the fuel ; for if the air-port be partly closed and there is a good draught on the kiln, it is evident we can force more or less air through the body of the fire, and maintain a perfect control. Mr. Guthrie has carefully analysed and estimated the expenditure of fuel in the manufacture of heavy clay goods, on the basis that loolbs. of prepared clay contains 37 lbs. of water free and combined, and has gi-aphically expressed his analysis by the diagram shown in Fig. 523. The perpendicvilar line represents degrees F. as well as feet, and the hori- zontal line feet only. The space embraced by the two perpendicular lines on the left of the diagram represents the extent of an ordinary kiln, and the total length of the diagram represents 1)hat portion of a continuous kiln which is occupied by the progressing part of the heat. The firing is supposed to take place at the extreme left, and the curved lines to show the temperature at any given point. The first division at the bottom shows the steaming stage ; the next indicates the calcining stage ; the division above that, the first burning stage ; and the two upper divisions, the burning stage of the more refractory goods. The total length is supposed to be 50 feet. " If we test a continuous kiln," Mr. Guthrie remarks, " we shall find the temperatures not very far from those indicated in the diagram by the curved line ; therefore, if we calculate the area of the burning stage beyond the in- termediate perpendicular line {x) and the end, and enclosed between the curved line and the exit temperature line, we find that aniount of heat utilized which must be the amount that would otherwise have gone up the chimney. The deduction for loss by conduction and radiation, how- ever, has not been made ; lines, therefore, showing the actual temperature would be below these. In my calculations so far, the temperature of the exit gases is supposed to be 500°, This, however, is found to be much higher than is necessary for a con- tinuous kiln of good construction." Mr. Guthrie's analysis of the expenditure of fuel is given in an elaborate table, which jve copy from his paper in the Journal of the Society of Arts.* In the kilns employed for burn- ing or expelling the water and car- bonic acid from limestone, the fuel is generally stratified with the limestone in the manner shown in Fig. 524. The kiln being once fired, the combustion is kept up by the consecutive layers of coal, and the lime is drawn at intervals from the bottom of the kiln. It is probable that a similar airangement to that introduced by * "Jour. Soc. Arts," 1880, p. 239. EXPENDITURE OF FUEL IN KILNS. 635 o mo 0\m I ^ « m to M « N OMft 1 H 00 4 -■ « N ^2 3- HOI + 1 N ■* « ^ N 00- - p) - as ? «3 ■- 00 q ^ o 00 M 1 On 0^\0 00 00 N Tt -(fiOVO ! VO •m '"1 '<-> o M O N m O* N fO u-1 n cl r>. '- n M « « m « N m 00 u^ « tn M VO O IM O O r^ « H U^U^M - M N ^2;T « « '-' « 000 « »"K e^ On On ON 1-1 u-j ryi fO I^ 5 ON § S| Ov 00 10 ?^ m w « 8 Tf v>\0 V? !>. OS WOO M ro «? •-" (1 CO 00 « Tj- ^ *nvO « OnOO £'2 o « • + l|g ■ . . OS EO (S N * for^.9 VO m-g . c c o I *3 '5 ^^ 2 S g 5.> go 00-^ ^ .> 3 ,£ VO fe rt >-.^ On VOOO*^ I ^ bo d ■ + K 0) g c ai P IS ■ s^ <» . ^ g;a to . ^ ^J Ml I be be S r« = = g K.2.2 «8 S g 2 £ .■S 60 B c "■5 ^ -^ O B .. B hHHEh 0000 !g fO a NO g §=" H a) 'oi CW gS8 So" b3 .a B^ B B t» a I n 2 ffl ■janjjo ■qi jad s^mn iBinaaq; ooo'g }y IBOiaaq} ooS'S ly . . 10 + M a •T3o 01"*° '• &« 0_e S-i c ba • c ^.g. > e g u 2 =>^■S S £ • £•« S o.^ £ -."S •sg^- ^C 11" st;^ 5 ■- 60 t. ECU ■=■« 0. ,o-S " Si's H § 1 H te £ >o t^ Oc- < ■qi lad e^inn IBuiJsq} ooo'S i)Y 636 FURNACES— CALCINING KILNS. Mr. Dunnachie for burning fire-bricks, described on pp. 627, 628, would make Fig. 525. the best lime-kiln also. Where wood and turf are employed as fuel, an ar- rangement similar to that employed in the potter's kiln is adopted. Mr. Herbert Guthrie, C.E., has proposed the form of kiln shown in Fig. 525, in which the fuel is kept separate from the limestone (see " Jour. Soc. of Arts," No. 1432, vol. xxviii., Feb. 20, 1880), and the air for combustion of the gases issuing from the producer alongside is heated by being drawn up through the burned lime which is cooling. This, with the difierence of a separate gas-producer, is a similar plan to that proposed in 1878 and 1879, in a series of articles on Calcination, in the journal "Iron " ; * see also " Proc. Cleveland Inst. Engineers," June 9, 1879, p. 242. These articles, however, deal principally with the calci- nation of iron ores by gas, but de- scribe the heating of the air for combustion by passing it through the hot stone which has been burned and is cooling. The mere burning by gas was carried out at Coltness Ironworks in 1851 or 1852 (see p. 228, and "Practical Mechanic's Jour."for April 1852). Regenera- tive calcining kilns worked by gas have been introduced in Sweden for calcining the Dannemora iron ore. (See " Jour. Iron and Steel Inst." No. I, 1882, p. 408.) Furnaces. — The furnaces employed for the various purposes of metal- lurgy, &c., are essentially of two kinds: first, those in which the fuel is Fig. 526. brought into direct contact with the substance to be operated upon; and, secondly, those in which the flame only is employed. Both may be aided by an artificial blast of air. To the first-class belong the furnaces ejn- ployed in many countries for roasting ores, which are in every respect similar in principle to the lime-kiln described above. The ordinary calcining kiln for iron ore used in the Cleveland district is illustrated in Figs. 526, 527. Fig. 526 being a vertical section, and Fig. 527 show- ing horizontal sections through the body of the kiln and through the discharging doors. The same operation is sometimes carried out in ore kilns when the mineral is of such a nature as to continue the combustion spontaneously which has been once commenced. • " Iron," 1878, pp. 6.^2, 674, aud 706 ; 1879, pp. 165. 196- a^d 227. BLAST FURNACE. 637 Thus, Fig. 528 shows the simple kilns on which copper pyrites and the pro- ducts from the first fusion of the ore, called matt, are calcined or roasted, being placed upon a bed of brushwood, which, when ignited, sufficiently heats the ore to enable the combustible matter contained ^^^ in it to continue a slow process of combustion. The vacant spaces in the walls tend to increase the draught. Mr. H. Aitken, of Falkirk, introduced an ingenious method of calcining the carbonaceous black-band by a coking process. The volatile products of distillation were thus secured, and the fixed carbon left combined with p,g 528. *^® ^^°^ oxide so that it was avail- able for reduc- tion in the blaet furnace. A smith's forge is, perhaps, the simiplest adap- tation of a blast to increase the temperature of fuel for working metals ; a current of air being thrown by a bellows into the fuel where it is in contact with the metal to be heated. Much of the lead-ore in this country is melted and reduced in a furnace constructed upon similar principles, and called an ore-hearth. It is shown in Fig. 529, as improved by Dr. Richardson. The blast enters from behind," and the flame and lead smoke, termed fnme, are seen escaping over a bridge into a main flue at the back. The Fio. 529. i-ore is thrown in through an opening at the side, with peat or coal. The temperature is not very high, and is easily regulated. Great economy of fuel is secured by the use of this kind of furnace, which is, however, only adapted for rich lead- ores. Blast rurnace. — The blast furnace used in the manufacture of iron also belongs to the class in which the fuel is in contact with the substances acted upon by it. On this account, it might be considered as of somewhat primitive design as a heating furnace, but investigation has resulted in 638 ACTIONS PROCEEDING IN THE BLAST FURNACE. demonstrating that a variety of actions on a large scale is continuously carried on in this furnace, which it is improbable could be so completely embraced in any other appliance of anything approaching the same moderate dimensions or involving the use of so little labour. These actions include (i) saturation of the carbon of the fuel with oxygen; (2) reduction of the oxides of iron ; and (3) the proper distribution of temperature for the various operations. 1. Saturation of the carbon of the fuel with oxygen involves certain limits of temperature, space, and time. Carbonic acid is first formed from the solid carbon at a high temperature in the region of the tuyferes. This carbonic acid requires for its reduction to carbonic oxide a sufficient quantity of solid carbon, at a moderately high temperature, and sufficient time to traverse it, or to remain in contact with it. 2. The reduction of the ore, or oxides of iron, also demands certain limits of temperature and time. Ores vary to some extent in the readiness with which they give up their oxygen, and with respect to the temperature at which reduction^ takes place most readily. The carbonic acid formed by complete combustion of the carbon in the hearth, where the high temperature is required for fusion, should be reduced to carbonic oxide (as in i), and again oxydized to carbonic acid by reducing the ore, so that in the resulting gases there should be 30 per cent, of the carbonic oxide formed into carbonic acid, or each unit of carbon as carbonic acid in the gases should be accom- panied by two units as carbonic bxide. If the temperature is too low, this result will not be attained, and, on the other hand, if the temperature is too high, ferrous oxide has the power of becoming re-oxidized by reducing in its turn the carbonic acid to carbonic oxide, and thus neutralizing the reduction from ferric oxide previously effected by means of the carbonic oxide. It has also been observed that the reduction of the oxide of iron is a heat-producing action. 3. Distribution of temperature according to the requirements of these, and some minor, operations is a question of the capacity of the furnace in proportion to the initial heat which is employed. WhUst intense heat is required for fusion, the quantities or proportions of solid carbon and hot air us$d to produce this heat^ determine the requisite capacity of the furnace to provide space and time for heat interception above. This affects all the actions, the saturation of the carbon with oxygen, the reduction operations, and the final passing of the gases off at the proper temperature and point of saturation with oxygen. In addition to these points, it is to be remarked that the descent of the solid materials in the furnace, and the ascent of the gases, take place automatically. The form of the blast furnace used in the manufacture of pig-iron in Britain is shown by the sections in Figs. 530, 531,532 ; one of these (Fig.531), showing the modern form used in the Cleveland district,* and Fig. 532, showing a good specimen of blast furnace for working with haematite f ore. The blast furnaces in Scotland J and in Staffordshire rarely exceed the dimensions of the latter Fig. 532, on account of the use of raw coal, instead of coke as at Middlesbrough, as fuel in them. Coke, from superior hardness- or strength, can resist a much greater crushing stress than coal is able to stand, hence furnaces charged with coke . are made of much larger dimensions. At one time it was supposed that the sizes of blast furnaces might be increased with advantage almost indefinitely, and that the * See papers by Sir I. Lowthian Bell and 0. Cochrane in "Jour. Iron and Steel Inst.," and "Proe. Inst. Mech. Eng." t Article Iron, in " Chemistry," published by Mackenzie ; W. Crossley, " Proo. Inst. Mech. Eng.," 1871. t P. J. Rowan, The Iron Trade of Scotland ; "Jour. Iron and Steel Inst.," 1885. DIMENSIONS OF BLAST FUENACE. 639 same rate of increase in the production of iron would accompany every increase in size. It was found, however, that this did not hold good, and that economy of working was not attained with very large dimensions. The following series of outlines illustrates the gradual increase in dimensions and capacity which took place during a number of years. (See Fig. 530.) -{3i> In working the blast furnace, the materials, consisting of iron ore, fuel, and fluxes, are charged into it at the top or tunnel head, generally through a cup and cone arrangement, which is used to close the furnace for the with- drawal of the gases without igniting them. The hot blast enters by the 640' METHOD OF WORKING BLAST FURNACE. tuyeres which are connected with the pipes leading from the hot blast stove's, and a zone of very intense temperature is created in the region of the tuyeres. The iron, which has been reduced from the oxide to the metallic state, in its passage with the charge down through the furnace where it has been exposed to a reducing atmosphere of carbonic oxide, is melted in this white hot zone, and drops down to the hearth, collecting in the crucible, or portion of the furnace just under, the tuyeres, from which it is periodically tapped and run out. The carbonic anhydride formed by the combustion of Fig. 531. Fig. 532. Blast Furnace, Eston IronworkB. Blast Furnace, Cumberland Iron and Steel Works. the coke with the hot air of the tuyeres in passing upwards, meets with solid carbon with which it combines and is thus reduced to the state of monoxide (carbonic oxide) ; this, to a greater or less extent, becomes car- bonic acid once more by combining with the oxygen of the iron ore in the upper part of the furnace. The hydrogen present in the furnace also acts as a reducing agent to some extent, but the carbonic oxide is not only the most abundant, but also the most active agent, so that Sir I. Lowthian Bell * has shown that the ratio of • " Chemical Phenomena of Iron Smelting; by M. L. Griiner. also " Studies of Blast Furnace Phenomena," DISTRIBUTION OF HEAT IN BLAST FURNACES. 641 CO _-? found in the escaping gases is the index of the working of the furnace. CO Sir I. Lowthian Bell says,* " The intensely heated gases which ascend from the hearth, having to perform the duty of reducing the ore as well as to heat the materials, the point which has to be kept in view in the con- struction of the blast furnace is, that its capacity should suffice for th6 Fm. 533. heated gases to be retained among the solids long enough to communicate to the latter as much of their sensible heat as is possible, and to become as completely saturated with oxygen as the nature of the chemical action will permit. These two objects seem to be attained in the Cleveland district, when the furnace has a height of 80 feet, with an interior capacity of about 12,000 cubic feet. These dimensions enable the gases to be cooled down to * " Principles of the Mauufacture of Iron and Steel." TT 642 CUPOLA FURNACES. such a point, and to be so saturated with carbonic acid as to retain little or no further power of reducing the ironstone of the country. The correctness of these views has been made apparent by the fact that furnaces, mentioned as haying been constructed upwards of 103 feet high, and others nearly as lofty, with a capacity of 40,000 cubic feet, have failed to show any marked advantage, so far as economy of fuel is concerned, over that which has been frequently obtained in those of more moderate dimensions." The two illustrations, Fig. 533, are given by this author to afford a general idea of the temperature of the materials filling two furnaces, one 80 feet high with boshes of 20 feet, and having a capacity of 15,400 cubic feet, and the other of 47 feet in height with boshes of 16 feet and a capacity of 6000 cubic feet. The temperatures marked on the figures were roughly ascertained by drilling holes in the sides of the furnaces at various heights, but these are considered by Sir I. L. Bell himself to be merely comparative from the fact that the contents of the furnaces may be hotter nearer the centre. He remarks on these illustrations : " The advantages possessed by the larger furnace are, firstly, that the gases pass away cooled, as far as it is practicable to effect this ; and, secondly, that the deoxidation of the oxide of iron is performed in a portion of the furnace where the temperature is so low as to avoid as much as possible the carbon acting on the carbonic acid, generated by the act of reduction. The comparative magnitude of this zone of moderate temperature in each furnace can easily be appreciated by an inspection of the two sketches. In the larger one the contents do not exhibit a dull red until a depth of 16 or 17 feet is reached ; whereas in the other this temperature manifests itself at a depth of about 9 or 10 feet. In each case the distance is reckoned from the charging-plates. " It might be supposed, at first sight, that the conditions of the two fvu"- naces could be brought into harmony by diminishing the rate of driving in the lesser. The increased period of time, however, during which the ore would then be exposed to the action of the heated gases only brings the hotter zone nearer the top' of the furnace, and an actual trial of slower driving extended over some time, induced me to think that there was no gain to be expected from a change of that kind." Sir I. L. Bell's description of the arrangement of temperatures is, how- ever, accepted by Mr. Charles Cochrane* and other authorities as showing the order, but not the proper extent of some of them, as, for instance, the cool region at the top. Cupolas. — Cupola furnaces f used in foundries for melting iron for the production of castings are also worked with solid fuel, usually coke, in con- tact with the charge of iron, the furnace being worked by a blast, usually of cold air. Similar furnaces are used in some copper smelting operations. A very interesting and useful resvmve of the progress in cupola furnace design has recently been presented to the Cleveland Institute of Engineers by Mr. Charles Hornung, of Middlesbrough, who has permitted us to make the following quotations from his paper : — " Originally cupolas were square, round, or oval in section, and provided with a single tuyere only, the lining being composed of a refractory sand rammed up around a metal core to the desired shape ; but this lining was found to wear away very rapidly, and required frequent repairs, hence it came about that the sand was gradually replaced by fire-brick. The height of these cupolas was usually only about 6 feet, and the consumption of fuel * See " Jour. Iron and Steel Inst." No. i, 1885 ; see also Bagnall on the Development of Heat in Blast Furnaces: "Jour. Iron and Steel Inst.," ii. 1871, p. 245. t Refer to "Jour. Iron and Steel Inst,," vol. i. 1884, p. 197, ii. 1882, pp. 741, 780, 783; " Scientific American," Nov. 1884. IRELAND'S CUPOLA. 643 reacfled as much as 10 cwts. per ton of metal melted. The capacity of these cupolas was found inadequate for all but the lightest work, so, in order to coUect a larger quantity of iron in the crucible, or lower part of the furnace, five or six tuyeres were placed on either side of the cupola, one above the other, about 10 inches apart, and connected outside by vertical pipes, only one tuyere being used at a time. When the blast was turned on, all the tuyere holes, excepting the lowest one, were closed ; then, as the melted metal in the crucible rose up to the level of this bottom tuyere, it was stopped up and the next above it opened ; and so on, in rotation, until the top tuyere was open and those beneath it all stopped up, after which the metal was tapped out in the ordinary way. "About the year i860, Mr. Ireland patented a cupola (Fig. 534), the lining of which was made smaller in diameter at the tuyeres. The supe- Fio. 534- 5'io. S3S- riority of the working of this furnace over those generally in use at that time was due to the more careful system of charging adopted and to the better proportioning of the internal shape. The method of working as described by Ireland was as follows : — After lighting up and heating the cupola by means of a smg,ll fire kindled in the usual way, 7 cwts. of coke were charged, and on the top of this i ton of pig iron, broken up into pieces about 10 inches long, next 2 cwts. of coke and i ton of iron, the subse- quent charges being about ij cwt. of coke and i ton of pig, according to the quantity of metal required. The cupola contained, when full up to charging level, about 6 tons of pig iron and 15 cwts. of coke, or 12^ per cent, of coke. " Owing to the gradual narrowing towards the tuyeres of the internal diameter of the Ireland furnace, the charges obtained a regular descent, and, owing to the combustion being concentrated in a smaller space for the same amount of coke burnt, the temperature immediately in front of the tuyeres was much higher than in the ordinary cupola with parallel sides. In order to allow of collecting and keeping a good supply of melted metal, Ireland T T 2 644 STEWART'S CUPOLA. increased the diameter of the lower portion of his cupola, generally termed the crucible or well. The tuyeres were placed in two horizontal rows, sixteen tuyeres about 3 inches diameter in the upper, and four tuyeres 8 inches dia- meter in the lower row. This does not seem to have effected much economy, but only to have increased the melting zone, as may be seen by considering Fig. 535, where a a represents the centre line of the row of lower tuyeres, and cc the row of upper and smaller ones ; in both cases, carbonic oxide is produced just above the tuyeres, at 6 5 and a a respectively, in consequence of the upper tuyeres c c being introduced at a point in the furnace where the coke is of such a high temperature that it ignites on the further com- bustion of carbonic oxide and oxygen. " The Stewart cupola (Fig. 536), commonly known as Stewart's rapid cupola, is proAdded with three rows of tuyeres close together, which produce Fio. 536. an effect similar to that of Ireland's arrangement ; the melting zone is also increased, and the metal has to pass through a greater space, where it is subjected to the oxidizing influences of the incoming blast. To some extent thi.s oxidation of the molten metal is prevented by raising the hearth of the furnace up to within a few inches of the tuyeres, and having, in place of the well or crucible for the melted metal, a separate receiver connected with the cupola by means of a brick-lined spout from its hearth level. This receiver WOODWARD'S CUPOLA. 645 IS entirely lined and roofed with fire-brick, and is provided with the necessary tapping and slagging holes. Leading off from the roof of the receiver to about the centre of the charge in the cupola is a pipe, lined with fire-clay to about 2 inches diameter ; this pipe carries away the heated gases from the surface of the molten metal and delivers them into the centre of the descend- ing charge, which is thereby partially heated before arriving at the melting zone. Owing to the depth from the hearth level being so very much smaller than in other cupolas, the coke for lighting up is considerably reduced. The difficulty of Stewart's arrangement, however, seems to be in the receiver itself ; this is apt to become clogged up with slag, and has to be cleaned out Fig. 537- entirely every night, which is a great in- convenience in the case of working for two or three days with the same furnace. " Heaton patented a cupola worked by means of the draught caused only by the height of the chimney and the ascensional power of hot air, instead of forced blast, but this method was slow and entirely unsuited for intermittent working. "Woodward's cupola* (Fig. 537) was worked by means of an induced current created by a steam jet blowing up the chimney. There were two rows of rect- angular tuyeres, or, rather, holes, for the admission of the air, usually eight in the upper and four in the lower range. The jet was a simple contracted nozzle, fixed in the centre at the bottom of the chimney, about 4 feet above the charging level. The steam for creating the draught was said not to be greater than would be re- quired for driving an engine and fan. "Woodward claimed that the coke con- sumption in one of his cupolas for ordi- nary work was about 10 per cent, of the metal charged, including 'hghting up.' The charge was introduced by means of a hopper at the side of the furnace. The first cost of such a cupola and plant was much reduced owing to the absence of an engine and fan, but it is doubtful if the actual results were as good as those given in some accounts ; at all events, this system of working seems never to have come into general use. " Some of these difficulties appear to have been overcome in the Herbertz cupola (Kg. S38), which in the place of tuyeres is provided with an annular opening, so constructed that it can be varied in height as required according to the working of the furnace. Steam consumption is given as about 203 lbs. per hour, with a jet f inch diameter, and a comparison of this with a cupola of similar dimensions worked with forced blast from a 3 h.-p. Root's blower which required about 198 lbs. of steam per hour, shows there is no economy obtained by means of the jet. The consumption of coke in two experiments mentioned in Stahl und Eisen, in June 1886, was 5 per cent, and 10.2 per cent, for melting only, and 9.9 per cent, and 12.7 per cent, total, including * See F. Kohn's •' Iron and Steel Manufacture," (London : W. Mackenzie.) 646 nEEBEETZ AND KEIGAE'S CUPOLAS. lighting up, or, taking the mean, it equalled over 2 cwts. of coke per ton of metal melted. " Analyses of the gases at the top of a Herbertz cupola in the experiments above referred to, show carbonic acid 10.7 to 11.5 per cent., carbonic oxide o to 3.4 per cent., and oxygen 6.7 to 8.2 per cent., or an average of 7.5 per cent, of oxygen. This 7.5 per cent, of oxygen is in excess of that required for combustion, and robs the furnace of considerably more beat than would the escape at the top of the charge of 2.55 to 11.73 o^ carbonic oxide. The excess of oxygen in an ordinary cupola causes extensive decarburization of the metal, but in the Herbertz system its action is not so injurious, owing to the melting zone being smaller, and the iron being consequently exposed to the action of the gases for a shorter time. Fio. 539- Fio. 538. " Krigar's cupola (Fig. 539), with a receiver and induced current, was arranged so that the air, instead of passing up the shaft of the cupola, entered at two or three different levels below the top of the charge, and was drawn downwards towards the melting zone by means of a steam jet placed m a chimney on the roof of the receiver. The gases helped to keep up the heat of the metal collected in the receiver, but the charge arrived at the melting zone almost cold after the passage through it of the cold air. The consumption of coke averaged about 13 per cent, as compared with the melted metal. The waste of iron was reduced \iy this system, because the molten metal was not subjected to an oxidizing atmosphere of ascending air. DUFEJfiN^'S GAS CDPOLA AND OTHER PLANS. 647 " Dufren^ patented an arrangement (Fig. 540) of a gas producer con- nected direct to an ordinary cupola. The air for the combustion of the Fig. 540. producer gas circulated round the sides of the producer, and so became heated previous to uniting with the gas inside the cupola. The gas wa.s admitted at the top of the crucible portion of the furnace, about the height at which the tuyeres are usually placed. Just above this gas port was a grating, composed of refractory material, on which the pig iron to be melted was placed. [Other plans of gas cupolas will be found in the section on gas furnaces.] " An arrangement of Siemens regenerators working in connection with a cupola was brought out in 1884, by Mr. Bramall, of SheflS.eld. Each of the regenerators was alternately heated by means of the waste gases from the cupola, previous to the introduction of the producer gas. This appears, however, to be based on a wrong system, for in order to heat the regenera- tors, the waste gases must be at a relatively high temperature, which would only be the case when the cupola was working badly. " Another cupola working on a similar system was brought out by Mr. Henry Krigar, of Hanover. It consisted of two distinct shafts and a receiver. The pig iron and scrap were charged into the shaft most remote from the receiver, which shaft was left open at the top, the fuel being charged Into the second shaft, which was closed at the top. Blast, admitted into the stack of fuel only, passed through the lower portion of the coke and ascended the shaft containing the pig iron ; by this means, the melted metal came in contact with the coke previous to passing into the receiver, " At one time the utilization of waste heat at the top of the charge was considered to be one of the most important points in the economical working of a cupola. This was effected in various ways. First, the blast was passed through a series of pipes placed in the chimney of the cupola, but this arrangement was costly compared with the results obtained. Then, the waste heat was made to traverse a chamber in which the iron and coke was stacked previous to being charged into the furnace ; but very little, if any, 648 UTILIZATION OF WASTE HEAT IN CUPOLAS. economy was derived. At Woolwich, a cupola was erected having a blast box extending over its entire height from the tapping-hole to the charging level ; the blast entered at the top and was raised in temperature by the heat radiating from the walls of the furnace. Attempts have also been Fig. 54 1, I made to utilize the waste heat for raising the steam necessary for driving the fans, &c. But none of these ideas has proved successful, owing to the irregular and in- termittent working of foundry cupolas. " In the different systems already men- tioned, with the exception of Ireland's, this fundamental fact seems to have been en- tirely disregarded — namely, that carbonic acid coming in contact with red-hot fuel combines with a certain quantity of carbon to form carbonic oxide, thereby robbing the coke of some of its carbon ; the com- plete conversion of the coke into carbonic &- - J). acid seems to have been only a secondary ^^ consideration. In an ordinary cupola. with one row of tuyeres, usually placed about 2 feet 6 inches above the metal in the crucible, the carbonic oxide formed by the combustion of the coke in front of the tuyeres a a (S^g. 541), comes in contact just above, at h b, with a layer of incan- descent fuel, and a considerable portion is converted into carbonic oxide, which, having no oxygen to combine with, rises to the surface of the charge, and, meeting with the oxygen of the atmosphere, burns, if hot enough, with its characteristic blue flame, or, if too cold to ignite, passes away invisibly. " Voisin (see Fig. 542 ) employed two rows of tuyeres, the upper row being placed at the level at which the formation of carbonic oxide was greatest, this level being ascertained by taking the temperatures at different heights. Undoubtedly he was on the right road, and deserves all the credit due to a pioneer ; but his efforts met with only partial success ; and this for a very simple reason — namely, that the combustion of the carbonic oxide at once ignited the hot coke, and, in fact, caused an upper zone of fusion, above which the original process was repeated by the absorption by the carbonic acid of an equivalent of carbon from the glowing fuel, and the consequent reduction to carbonic oxide and loss of heat. " Since then several attempts have been made to utilize the waste gas more completely ; but they have invariably stumbled at the dilBculty of burning thfe gas without attacking the solid fuel. This difficulty, however, at la^t appears to have been overcome ; Arthur Greiner and Thuisco Erpf, as the result of some experimenting, having adopted the plan of arranging a number of small blast inlets over an extended upper zone of the body of the cupola, through which, by careful manipulation of the blast, they have managed to convert practically the whole of the carbonic oxide into carbonic acid below the surface of the charge (see Fig. 543). "A very 'thorough exposition of Greiner and Erpf's invention appeared in the Engineer of December 9, from which the following is quoted : — " Messrs. Greiner and Erpf, in their endeavour to solve the problem of the utilization of the inevitable carbonic oxide, after careful study of the phenomena attending combustion in cupolas, have made an entirely new departure. They perceived that, to effect the required result, the combustion. VOISINS AND GEEINER AND EIU'F S CUPOLAS. 649 of the carbonic oxide must be commenced at a point so far above the fusion zone that the descending coke has not attained the temperature necessary for ignition, while the ascending combustible gas is still hot enough to ignite on contact with air. Furthermore, the burning of the gas must not take Fig. 542. , place in one horizontal plane, but must be distributed through some depth of the charge, otherwise the concentration of heat would cause ignition of the coke, and consequent loss. The drawing (Fig. 543) shows a section of a cupola on this system, the supplementary blast being introduced above 6so GEEINER AND ERPF S CUPOLA. Fig the point where the fuel has not quite attained the temperature necessary for ignition. The carbonic oxide is thus burnt to carbonic acid, and the descending mass of coke and metal receives the full benefit of the combustion temperature j while, owing to the method of distributing and regulating the supplementary blast, the heat at no point is great enough to fire the coke, or to permit of any reaction between it and the car- bonic acid. The upper blast is introduced through a number of small tuyeres placed around the cupola in such a way as to secure a thorough distribution of the air currents.' "The analyses made by Messrs. Pattinson and Stead show that this invention efiects in a very com- plete manner the utilization of the carbonic oxide. The samples were taken from the waste gases just above the charge, near the inside lining of two cupolas at the works of the Anderson Foundry Company. One of the cupolas- was of the ordinary first-class foundry pattern; the other was a similar cupola altered to Greiner and Erpf 's system. Ordinary Cupola. Nitrogen .... 75-5° % Carbonic oxide . . I I.Jo Carbonic acid . . . 12.50 Hydrogen .... 0.50 Greiner and Erpfs Cupola. 19-92° L 1. 25 18.75 0.08 " Messrs. Fattinson and Stead, in a note on these analyses, say : — * The results show that the heat de- veloped in the cupola, where the gas produced at the main tuyeres is burnt by air injected above, is about 30 per cent, greater than is developed in the ordinary cupola. JFor many reasons the practical saving of coke in large cupolas will not reach that point, but the results prove beyond doubt that the system is a correct one, and must produce a considerable economy of fuel.' " From these analyses we find that in the ordinary cupola 9,438.2 heat units are developed per lb. of carbon. Taking the melting-point of cast iron as 2780° F., its specific heat as 0.13, and 40° F. as the average tempera- ture of a pig of metal, coke containing 89 per cent, carbon, we get — 2780 — 40 = 2740 X 0.13 X 2240 9438.2 X o.8<, the amount of coke required to melt i ton of cast iron. " To this must be added the following : — Melting slag and burning limestone . . ] Carbon burning to CO . . . . . f = 20 lbs. Blag per ton of metal . . . . j Carried off by waste gases at temp. 770° F. . . = 6 7o for radiation . = = 95.00 lbs. 2.87 lbs. 9-9° .. 5-7° >• Total coke per ton of metal melted . . . =113.47 „ " In a similar manner, from the analysis of the waste gas from Greiner and Erpfs patent cupola, we find 13,465 heat units developed per lb. of carbon^ and using the same calculations we get — eichaedson's silvee-lead fuenace. 651 2740 X 0.13 X 2240 , „ 2780 - 40 = 13465 X 089 = 66-^ "'«• ''°^^ ' adding the following : — Melting slag and burning limestone . . ] Carbop burning to CD, f ^^ i .90 lbs. 20 lbs. slag per ton of metal .... J Carried oft' by waste gas at 770° F. . . . = 9.90 „ 6 7o for radiation • z= , 4.00 „ Total coke per ton of metal melted . . . = 82.40 „ or a reauction in coke consumption of about 27 per cent., as compared Avith the ordinary cupola." Metallurgical and Chemical Furnaces. — Eichardson's furnace, Fir. ■;44. Fjg. 541;. Figs. 544, 545, and 546, for treating silver residuums from zinc-ores, &c. &c., furnishes another illustration of the application of the blast. a is the body of the furnace, formed of single Fio. 546. brick, and the bottom of clay and finely ground coke, well beaten down, and cut into the form shown in Fig. 544. The materials are thrown into the furnace Isy the charging door b, and a fine spray of water made to play upon their surface from a rose situated at c. The front of the furnace is supported by a metal casting d, over which the slag flows either into water or into metal tubs. When the silver-lead has accu- mulated in suificient quantity in the hearth, it is tapped into a pot at the point e. The furnace may be worked by means of a blast thrown into the furnace by the tuyeres fff, or by increasing the number of these openings to five or six, and connecting the furnace with a tall chimney, when the natural draught wiU be sufficient. The upper portion of the furnace g 6S2 REVEEBEEATORY FUENACES. is supported on four metal pillars and binders, h h h h, which remain un- touched on renewing the lower part of the furnace after being worked out. Furnaces in which the flame of the fuel alone is employed, are frequently called reverberatory furnaces. Where solid fuel is used it is burnt upon a grate, and the flame is drawn by a powerful chimney draught over the sub- stances to be heated, which are inclosed by a more or less elevated arch of brickwork. These furnaces are frequently constructed with the bed in two portions at different levels — on one of which the substance is partly heated or prepared while the other serves for the final heating or " furnacing." In some instances the higher part is called the "garret bed" and the lower the " working bed." The charge in many instances is first introduced at the higher level, which is further removed from the fire, and subse- quently raked down on to the lower level, where it is exposed to the full heat of the flame ; in some processes, however, the opposite course of Fio. 548. j^- — procedure is necessary. Furnaces of this description are employed in the manufacture of carbonate of soda. Figs. 547 and 548 illustrate an ordinary reverberatory furnace with single bed, Fig. 547 being an elevation, and ^ig- 548, a longitudinal section of the furnace. Amongst the furnaces used in chemical manufactures the mechanical furnaces of Mr. Mactear and of Messrs. Jones and Walsh have occupied an important position. MACTEAR'S AND JONES AND WALSH'S FURNACES. 653 The Mactear furnace* " consists essentially of a revolving bed or pan made of wrought iron lined with firebrick. This pan is carried on a series of girders which radiate from a hollow central piece of cast iron. These Fia. 549. girders carry each a bearing wheel, levelled on the tread, and the whole runs on a circular raiLor race having its upper surface bevelled to correspond with the wheels, and a flange on the inner side. The race is carried on iG. 550. two massive pieces of brickwork with a i-oadway between, through which the waggons run when the finished material is being discharged." In the carbonating furnace "the bed has an opening in the centre through which the finished charge is made to fall by being pushed out either by hand or by mechanical arrangements of a very simple kind." Mechanical stirrers are also used and the amount of labour required is therefore very small. • See J. Mactear. "Jour. Soc. of Arts," Feb. 4, 1881 ; "Jour. Soc. Chem. Ind. "June 28. 1S81. ^ 6S4 HAND FUENACE FOR SALT-CAKE. Fig. 549 shows this furnace as arranged for coal firing. Very good results have however been obtained by the use of producer gas in this furnace. The furnace of Jones and Walsh* is similar in general design to the Mactear furnace, being also a revolving bed furnace. Fig. 550 shows the combustion arrangements in a salt-cake furnace of this kind as worked with gas fuelf at the works of the Newcastle Chemical Company, Gateshead. The air for combustion is heated to 1000° F., and supplied under slight pressure '"■ ^5'* from a fan, and a saving of two shillings per ton of salt treated as compared with coke firing was announced by Mr. Allhusen. The old - fashioned hand furnace for making salt-cake which was displaced by such improvements as the foregoing is pretty well represented in Figs. 551 and 552, which re- present the ordinary combina- tion of bottom and surface heat for decomposing common salt. In the section, c repre- sents an iron pan, heated from below by a fire d, from above by those at e e. The drying flats // are separated from the pan by trick partitions, and communicate by means of openings at gg, which may^be closed with dampers. The bulk of the hydrochloric acid escapes at It, when intended for the manufacture of chloride of lime, and what is retained by the partially manu- factured sulphate at i i. The working- doors are shown at k k k ; the under- ground recess for stoking the fire by I, which is covered by trap doors m m, during the decom- position of the com- mon salt. Further improve- ments in such chemical furnaces have been introduced at the works of Messrs. Gaskell, Deacon & Co., Widnes, and of Messrs. Gamble at St. Helens, both of whom introduced what has been called a " plus-pressure " furnace intended to work certain portions of the manufacture of salt-cake in closed muffles. I'igs- 553) SS4, and 555 illustrate the "plus-pressure" furnace. Fig. 553 being a longitudinal section, Fig. 554 a transverse section through the muffle and pot, and Fig. 555 a plan in section showing the various heating flues. In all the figures, E is the muffle or close roaster, S is the pot, T is the • "Jour. Soo. Ohem. Ind.," June 28 and 29, i88t, pp. 33, 34. + See A. Wilson. " Jour. Sec. Chen. Ind., " Noh. 1883. Fio. 552. PLUS-PRESSUEE FURNACE. 655 grate, U the chimney or column of hot air causing the draught or propel- ling power of the fuioiace, V V are the smoke flues, W is the acid gas outlet, Fio. SS3- X a bye-flue for conveying waste heat to the ordinary chimney when the heat is not wanted under the pot, Y 7 are openings communicating with the air, and Z the ordinary chimney smoke flue. Fio. 554. Fig. S5S- -^i L\v\\vxvvv\\\\i\4i'vi\^;^?;^ 6s6 THE ST. BEDE CHEMICAL FUENACE. The most recent form of the salt-cake furnace is called the St. Bede chemical furnace, from its having been worked out at the St. Bede Chemical Works by Mr. T. Larkin. It is a combination of the old pan and roaster with closed muffles and mechanical stirring, and is said * to possess many advantages over other forms. Figs. 556, 557, and 558 illustrate this furnace,' Figs. 556 and 557 being sections at right angles to each other and Fig. 558 a plan of the furnace. Fig. 556. The bed a is made of fireclay quarls or metal plates, having a central opening for the shaft c of the mechanical stirrer which is protected by a tube or casing b. There are several small " lower " and " higher " fireplaces, Fio. S57- d, being one of the lower and e one of the higher, arranged at opposite ends of the furnace. The heat from d passes under a, and is conducted either by " flash flues " or by return flues into the main flue. The heated gases from e are directed over the covers/ of the furnace by means of flues until they reach the opposite end of the furnacBj where they • See "Jour. Soo. Chem. Ind.," May 29, 1885, pp. 316-318. ST. BEDE CHEMICAL FURNACE. 657 pass into the main flue or they may be brought down and under the bed by return flues and thence into the main flue. The cover or roof _/ is sometimes carried by the lower flanges of girders as shown at g. In this construction of furnace, the box chamber or receptacle bounded at the bottom side by the bed a, and on the top side by the cover/, has no direct communication with any of the flues which lead from any of the fire-places. This closed chamber has several doors, as at a", of suitable dimensions for withdrawing the finished charges. A pipe or channel h serves for Fia. 558. '==:^=!^^C^ \ 0, /^ \ \ \ / 1 \ y -T""" >js \ ■■ a-i :r-' Th horizontal section on the line AB, Fig. 575; Fig. 574 is a vertical section on the line LMNO, Fig. 573; and Fig. 575 is a plan in section on the line GHJK, Fig. 573. In this case, the blast was heated in the bell- shaped iron chambers h b, entering them at a, and passing from them by the passage c to d d and e, whence it passed partly into the producer _/, and partly by the pipe h to g, in order to supply air for combustion. The wood was chalrged into the producer through the opening g, and the flame and Fig, hot gases passed over i and I to the flue k, whence they were led to drying ovens for the wood. A furnace which bears some resemblance to this one was illustrated in "Engineering" (January 28, 1870), as having been introduced into the Newport Iron Works at Middlesbrough. Another interesting furnace, which may be classed among pioneer gas- furnaces, is illustrated by Dr. Percy ("Fuel," p. 517), from a drawing Fio. 573- supplied by Dr. H. "Wedding, of Berlin, this furnace having been used in the Mint and Royal Porcelain Manufactory at Berlin in 1861. In all these instances, the use of gas along with a blast of air, either heated or cold, producing in fact a blow-pipe flame on a large scale, is found. This system seems to have been introduced first in Sweden. Dr. Percy gives* a report from Mr. Sandberg on the working of Ekman's furnace "Metallurgy " : Iron and Steel, p. 427. X X 674 BLOW-PIPE GAS FURNACES. Fia. 574. which illustrates the practical differences found in working with cold- and with hot-air blast. Cold air gives a long blue flame, not hot enough to weld iron unless continued for some time, whilst hot air gives a short, white, and hot flame, able to melt wrought-iron with facility. This result is due to the combustion being more rapid and complete with the hot' air, the consequence of its higher temperature. In the Supplement to Dr. Tire's " Dictionary of the Arts," &c. (article Iron), London, 1846, some gas blow-pipe furnaces for iron manufac- ture are illustrated. M. P6clet also gave* full details of a gas furnace worked on the blow-pipe system with waste gas from iron furnaces, at Treveray, in France, at an early date, and illus- trations of it are given in the work of Mr. C. Wye Williams, t The blow-pipe system seems to have been almost entirely neglected in Britain for many years. Mr. Sutherland proposed in 1869 some ingenious plans for welding by gas with blast, which were subsequently practised to some extent in the works of a firm of tube-makers. A very successful use of the blow-pipe system was made in the ingenious puddling apparatus of Godfrey and Howson.J Figs. 576 and 577 illustrate |llT l . !lll|l l| d WAw ■-?>//*. this eipparatus, Fig. 576 being a sectional side elevation showing the gas main, air-pipe, air-heater, and compound blow-pipe delivering its flame into the rotating puddler. The flame and waste heat escaping from the puddler ascend through the stack of cast-iron air-pipes placed in an upright chimney which can be closed by a damper. The arrows in the illustration show the course of the flame and gases. Fig. 577 is a front elevation of the whole apparatus. * TraiU de la Chaleur. t " Ou the Combustion of Coal," &c., first edition, p. 68 ; " Fuel, its Combustion and Economy " (Williams and Clark), second edition, pp. 45-47. X B>. Howson in *' Jour. Iron and Steel Inst.," vol. ii. 1877 , see also ibid.^ vol. i. 1S72, p. BLOW-PIPE GAS FURNACES. 67S The results obtained with this apparatus, when worked with gas from separate producers, were excellent as to quality of produce and economical in fuel, and there seems to be no reason why it should not be employed in the manufacture of " open-hearth " steel. Various interesting applications of the blow-pipe principle to furnaces Fig. 576. have been proposed and carried out in recent years, not merely on a small scale by Mr. T. Fletcher, of Warrington, but also as applied to furnaces for boiler-making, welding, plate, and rivet heating, glazing pottery, and smith- ing operations.* The following illustrations also show proposed methods * See "Engineering," Nov. 7, 1879; also E. Crowe in "Jour. Soc. Chem. Ind.," vol. i. 18B2, pp. 54, SS- X X 2 (>7e GAS CUPOLA FURNACES. of applying this principle to the melting of pig-iron for foundry use, and for the first stage of steel making by the " open hearth " process. FiQ. S77. Fig. 578 shows a "gas cupola" designed by Mr. Alfred Wilson* for the purpose of melting pig-iron as fast as an ordinary cupola, but with about 2 cwt. small coal or dross per ton of iron (instead of coke), the fuel being used in a gas-producer. The gas flue is shown shaded black, and two or more blow-pipes for air cross this flue and cause an intense flame to extend across the melting chamber. The pig-iron, without fuel, but with some limestone to flux the sand on the pigs, is stacked from the bed of the melting chamber and up the vertical chamber, and may be charged into this latter from the upper platform. The stack of iron partly absorbs the heat of the gases of combustion, and the remaining heat is communicated to the air- * " Proc. Cleveland Inst. Engineers," June g, 1879, p. 236. GAS CUPOLA FURNACES. 677 blast on its passage through the iron pipes in the two vertical chambers behind the melting one. Fig. 579 is another arrangement proposed for the same operation,* D being the gas flue, E the air blast pipe, B the melting hearth, and C the .Fig. 578. Fig. 579. /V^/ M/////fif. K. Clark, op cit., pp. 270, 271 ; JRevue UniverseUe des Mines, tome i. 1877, p. 20^^ ; "Jour. Iron and Steel Inst.," vol. ii. 1882, p. 760, vol. i. 1884, p. 83 ; " The Engineer," Aug. 3,' 1883; Dingl. Polyt. Jour., vol. ccxxvi. p. i6o. t " Jour. Iron and Steel Inst.," 1876, p. 109; D. K. Clark, op. cit., pp. 274, 275. X See " Jour, Iron and Steel Inst.," vol. i. 1884, p. 60. § See also D. K. Clark, op. ctt., pp. 276-284. || Op. cit., pp. 238, 332, 333. % " Trans. Inst. Engineers in Scotland," vol. ii. 1858-59, p. 79 ; see also ibid., April 18, 1871, p. 245 ; ".Tour. Iron and Steel lust.," vol. ii. 1871. 686 GORMAN'S HEAT EESTOEINa FUENACE. furnace. Mr. Gorman remarked* on this point that, "as the gas was not cooled after it left the producer, and the air for combustioji was heated to the highest temperature by the escaping gases, an intensely hot flame was projected horizontally into the furnace between the roof and the materials on the bottom or hearth, by which means combustion was effected without the flame impinging on the brickwork of the furnace or on the material which was being heated." The drawing of the furnace shows that " the roof rises upwards from the jet of flame, and that it is not inclined so as to direct the flame down towards the bottom or hearth, but that the flame has free scope for complete combustion." The " restorer " is a chamber placed usually under the ground line and containing a number of fire-clay pipes open at each end, the ends of the pipes being supported or carried by thin walls or partitions. The waste gases pass vertically downwards through the chamber in which these pipes are placed horizontally and heat the tubes from their outside surfaces. The air for combustion enters the end space at the bottom, passes through the FiQ. 594. pipes to the space at the other, end, rising to a higher series of pipes and re-crossing till it arrives at the top of the chamber; the effect being an upward current of air meeting a downward c.urrent of heated gases with only the thickness of the fire-clay tube between them, the current of air inside preventing the destruction of the tube by the high temperature put- side. The incoming cold air thus meets the waste gases when about to escape to the chimney, and extracts the remaining heat, whilst the hottest gases impinge on the pipes which contain the air already gradually heated up in ascending, and thus raise it to a still higher temperature. In advocating this form of heat-restorer and system of working, Mr. Gorman pointed out that it was not liable to the objection which he con- sidered was attached to the Siemens regenerator system — viz., that in heating coal gases up to and above a red heat they deposit solid carbon. He argued that this takes place in the Siemens regenerator, and that on the reversal of the currents the carbon deposited on the brickwork of the regenerator is converted into carbonic oxide by reducing the carbonic acid * " Proc. Phil. Soc. Glasgow," vol. xvi. p. 298. PONSAED'S GAS FURNACE. 687 in the hot products of combustion. " This chemical action," he said, " lowers the temperature of the escaping gases so as to indicate that nearly all the heat of the fuel has been expended in the furnace, whilst in reality a large part of the most valuable heating power of the coal does not get the length of the furnace, the carbonaceous gases being partly condensed by Fra. S9S- cooling (in the Siemens cooling-tube) and partly deposited by heat in the regenerator on their way to the furnace." It is probable, however, that Mr. Gorman over-estimated the loss which might arise from deposition of carbon in the regenerators. The action is known to take place to an appreciable extent when illuminating gas or gas 688 PONSARD'S GAS FURNACE. rich in hydrocarbons is heated, and would thus militate against the em- ployment of a richer gas in regenerative furnaces of the Siemens type, unless the air only were heated in the regenerators. As ordinarily worked, how- ever, the Siemens furnaces use a producer-gas which contains scarcely any hydrocarbons other than marsh gas, and, therefore, the decomposition referred to cannot take place to any extent worth noticing. Gorman's furnace worked with great economy, using only about 3I cwt.' of coal per ton of iron in mill furnaces, and was fairly durable, the only serious difficulty having been occasioned by the fire-brick pipes of the Fig. 598. restorer cracking under the action of rapid expansion or contraction, when the furnace was being heated up or cooled. Ponsard's furnace (Figs. 595, 596, 597) is of the same class as Gorman's, having a gas-producer attached to the furnace and a recuperator for inter- cepting waste heat and conveying it to the air supply above. Fig. 595 illustrates a sectional elevation of furnace, " gazogene " or producer, and recuperator; the producer shown being of the ordinary Siemens form with sloping grate fed with air at atmospheric temperature. M. Ponsard also introduced a form of " gazogene " without grate, which was worked with air heated in the recuperator. Fig. 598 represents a section of this " superheated gazogene," showing the openings for charging fuel from above and for withdrawing slag and ashes below. The air heated to from 1500° to 1800° F. traverses the mass of fuel, the gas escaping at a high temperature into the furnace. 1 The gain in heat utilized by this system is shown as follows : — Percentage Losses of Heat with Different Kinds of Coal. Metallurgical Furnace with Ordinary Produce. With Superheated Producer. Coal No I. No. 2. No. 3. No. 4. No. 5. Coal No. I. No. 2. No. 3. V0.4. No. 5. By production of gas „ the waste gases 10.9 314 9.8 29 8.35 28.2 7.8 27.3 5-7 25.6 16.2 18.3 .4.8 j8.o 14-35 18.50 12.0 18.0 zS.o Total loss .... Heat utilized (hy difference) . 42-3 38.8 3S.55 3S-I 1 31-3 34-5 32.8 32.85 30.0 27.0 57-7 1 61.2 «3-45 64.9 1 68.7 65-5 67.2 67.15 70.0 73.0 The Ponsard recuperator is built of fire-brick, the channels or passages for air and waste gases being formed by vertical diaphragms and perforated bricks. The hot waste gases occupy one set of vertical passages b (Fig. 597), through which they descend to the smoke flue, whilst the air ascends by the other set, c. Each set of vertical passages is alternately coupled together by perforated bricks, which add to the heating surface and serve to break up the currents, acting as baffle plates. The construction of this recuperator may be understood by reference to the longitudinal and transverse sections given in Figs. 596 and 597. Several interesting examples of the Ponsard system were carried out on the Continent, and their results are recorded in an exhaustive examination of the system by M. Sylvian Periss6* (Note sur le Four k Gaz avec Recup6ra- teur de Chaleur, Systfeme Ponsard, in Mem. et Compt. Bend, des Travaux de la Soc. des Ingen. Civils, 1874, p. 752, and 1875, p. 292), who gives the * See also D. K. Clark, "Fuel, &c.," p. 317, &c. EADCLIFFE'S GAS FUflNACE. 689 following comparison with the Siemens system as regards utilization of heat : — utilization of Heat with the Following Syatema. Different Kinds of Coal. Ko. I No. 2. No. 3. No. 4. No. 5. Ponsard furnace, with ordinary producer . „ „ superheated . Siemens furnace 57- 7 65.5 52.8 61.0 67.2 56.0 62.7 67.1 57-7 63 s 70.0 59- S 66.4 730 62.8 The latest development in this country of the gas furnace with con- tinuous regeneration and gas-producer attached to the furnace, is that of Mr. F. Eadcliffe, superintendent of the forge of the Royal Gun Factory at Woolwich. Fio. 599. Via. 600. Figs. 599, 600, 60 1 illustrate this system, which has been designed to avoid the expense of constructing regenerator chambers or passages below the surface, and to combine producer, regenerator and furnace in one structure. The illustrations show an open-hearth- steeUmelting furnace, Fig. 599 being a vertical section through the combustion chamber, regenerator and gas pro- ducer ; Fig. 600 is a sectional plan on the line A£ of Fig. 599 ; and Fig. 601 is a cross section through the line UFoi Fig. 599. The producers have grate bars and closed ashpits, as they are worked by a forced air supply, a pressure equal to 6 inches of water column being used in supplying this part of the apparatus. Half that pressure of air is found sufficient for sending the air supply for combustion in the furnaoe chrough the regenerator passages. Before the air supply is allowed to pass into the gas producers, it is heated, in cast-ii'on pipes, by means of the waste heat of the escaping gases, Y Y 690 EESULTS WITH EADCLIFFE'S FUKNACE. Fio. 6oi. to between 700° and 800° F. The gas thus produced has a conlparatively high temperature, and passes at once into the furnace. The regenerator is placed over the furnace, but is carried, by pillars and iron beams, clear of it, to allow of independent repair. It is constructed of fire-brick, the air passing to and fro through pipes or small channels, whilst the hot waste gases first descend and then ascend among these pipes in traversing externally their entire length. This construction has the merit of simplicity and of avoiding the necessity for numerous valves, the only valves required being those for regulating the air-supply to the gas producers and to the regenerator. The first furnace of this design which was erected for steel melting was tried at Woolwich during 1885. It was of a capacity for 6-ton charges, and worked for many months without cessation, the average consumption of fuel being 8.5 cwts. per ton of ingots produced. After undergoing some repairs, it was started on January 9, 1886, and worked without stopping until March 31, making 124 charges as follows: — Total weight of metal charged . „ „ ingots produced ,, „ fuel consumed . „ „ skulls and scrap . .-. The fuel includes 1 1 tons used in heating the furnace preparatory to working the first charge. The results obtained with this furnace were so satisfactory that a lo-ton furnace was built and started during 1886, the results of the working of which, as checked by the Store Department at Woolwich, were extremely good, showing, as was to be expected, a superior economy of fuel to the smaller furnace. The following statement gives the results of four consecutive weeks' working of the lo-ton furnace : — smenOtt nnreucM.S^, Tons. cwts. qrs. 822 10 786 12 3 339 II b 16 3 Totals Week endinpr Week ending Week endinit Week ending Four Weeks June 26, 1886. Julj 3, 1886. July 10, 1886. July 17, 1886. tons cwts. qrs. ending July 17, 1886. tons cwts. qrs. tons cwts. qrs. tons cwts. qrs. tons cwts. qrs. Total weight of charges lOI 10 78 ID 96 5 97 373 5 Weight of ingots made 96 IS 75 6 3 91 9 3 91 14 355 5 2 Skull and scrap . « 3 2 ' 3 I 16 I I 8 582 Coal consumed . 29 5 24 0,0 26 17 27 5 107 7 Averase. cwts. cwts. cwts. cwts. cwts. Fuel per ton of ingot . 6.04 637 . 5.87 5 94 6.04 The coal consumed in maintaining the heat in the furnace from Saturday till Monday is included in this statement. This system has, since then, been developed in the Royal Gun Factory, and will probably be extended to other works. The use of gas-producing fireplaces attached to furnaces has been developed on the Continent, and to some extent in Britain, in connection with the firing of the furnaces for heating retorts in gas-works. Several of GAS ANNEALING AND EVAP0EATIN6 FUENACE. 69 1 these plans are described at pp. 611-617. Mr. Hartmann, and Mr. Haupt,* of Brieg,also introduced some ingenious forms of such gas furnaces Fig. 602. as applied to steam boUers, and the latter obtained remarkably good results in comparative trials with a hand-fired boiler (see p. 556). Fig. 602 illustrates a gas annealing furnace designed and introduced by Fig. 603. Mr. A. Wilson of Stafford, to work in connection with a separate gas producer, a is the air inlet or valve, B the gas valve, c the gas flue, d the * See Chemiker Zeiiung. 1880. p. ago : " Engineering," Jan. 2, 1880. Y T 2 592 GAS MUFFLE FUENACE. passages for entrance of gas into the mixing chamber, where it meets the air which has been slightly heated in the passage, e, which runs under the furnace bed. p is the chimney flue. An application of gas firing to evaporating is shown in Fig. 603, which illustrates a form of gas furnace for brewers' coppers, designed by Mr. B. Dawson, of Malvern, and carried out by him successfully in several breweries in England, a is the air dnlet, b the gas valve, c the gas flue from producer, D the flue for gas after passing through the regulating valve b. The arrows Fig. 604. show the course of the flame and hot gases round the bottom of the copper and down to the chimney flue e. Fig. 604 is a design also by Mr. Dawson, and, like the previous one, uses air of atmospheric temperature, as a low heat is all that is required in them. This figure shows a gas Fig. 605. /^:ff-^I!!^-iiv^ muffle furnace for heating copper, and is of simple construction. A method of applying regenerators of the Siemens reversing type to boiler furnaces, which has been designed by Mr. Hill, is shown in Fig. 605. It would be impossible to illustrate or describe all the possible applications of gas to furnaces, because they are as numerous as the applications of fuel, and it may safely be said that, as intelligence spreads, no other systefai of utilizing solicj fuel will survive. The Practical Effect of Fuel. — It has already been repeatedly men- tioned, that the efiect obtained by fuel in practice is very much below what it should be according to theory. The causes of this are partly fortuitous ; partly, however, they pertain to the nature of the process, and are consequently unavoidable. The maintenance of a draught in the chimney, to which a portion of the heat evolved is always sacrificed, is one of the more important sources of loss. By reference to a former page, it will be seen that i lb. of dry wood requires on an average 5.94, or, in round numbers, 6 lbs. of air of 0° ( = 148 cubic feet) for perfect combustion : suppose this air to escape with a tem- perature of 150° C. into the chimney, the quantity of heat then contained PEACTIOAL EFFECT OF FUEL. 693 in it. will be as great as that contained (in i lb. of air at x 150° = 900° or) in 9 lbs. of air at 100*, and consequently in = 2.1 lbs. of water at 100° C. According to Schodler and Petersen, i lb. of dry wood will heat on an average 40.6 lbs. of water to 100° : the action of the chimney, therefore, 2. 1 causes a loss of — '—> = o.o';2, or K.2 ner cent., which loss increases with the 40.6 J ' J ' temperature of the escaping air. A portion of the fuel is also prevented from combining with oxygen and evolving heat by the lowness of the temperature in the immediate vicinity of the sides of the fireplace, and at least twice as much air is usually admitted as is theoretically required ; this also diminishes the temperature, whilst the occasional obstructions to the proper access of air through the grate bars farther lessen the efficacy oi the fuel. These impediments to perfect combustion cause a portion of the fuel to be converted into volatile or non- volatile products, which are mechanically carried away by the draught to the remoter parts of the chimney, where they pass off as smoke. The smoke, when it consists partially of unburned hydrocarbons, mixed with car- bonic oxide, is still capable of uniting with oxygen, and of evolving a quantity of heat equivalent to that portion which is lost. The combustion in the fire- place is therefore a partial process of dry distillation : instead of the vapour of water, carbonic acid and nitrogen being the sole products, these gases con- stantly pass off mixed with smoke, which partly collects as soot. The smoke- consuming arrangements in stoves affect to burn the smoke by bringing it into contact with a stream of hot air. The condensable portions of the smoke, as well as the water formed during combustion, absorb heat in being converted into vapour, and this heat is, for the most part, lost. The loss occa- sioned by the hygroscopic water, from which fuel is seldom free, is still greater. In the first place it diminishes the weight of the combustible — i cwt. of wood, for instance, only containing 80 lbs. of actual fuel — and secondly, the water absorbs a large amount of heat in being converted into vapour. For this reason, Rumford's experiments (with common wood) give a smaller result than those calculated from the analyses (with dry wood), although the heat of the vaporized hygroscopic water is not lost in the calorimeter, as it is in practice, being in the former case condensed again into water. Wood, in the ordinary air-dried condition, contains about ^^th water, and only f ths of actual fuel; of the 40.6 lbs. of water which i lb. of dry wood heats to 100°, ^—^— = 8.1 lbs. are left cold; besides, every |^th lb. absorbs as much heat as corresponds with yth x 5.5 = 1.1 lb. of water at 100°. Altogether, there- fore, the moisture in the wood causes a loss of heat = -^ -^— = 22^ per 40.0 "* ^ cent. This clearly explains the economy of dry fuel. For domestic purposes, it is generally too costly, and not practicable, to dry the wood by artificial means ; while, for certain appKcations in the arts, dry fuel only can be employed. Fig. 606 represents a section of a drying kiln for fuel, first introduced in the French glass-houses. The whole space covered by a single roof is a long quadrangle, and contains six arched passages AAA, 60 feet in length, 6 feet broad, and .5 feet high, which may be viewed as separate stoves, each having its own fire ccc. Each fire-place extends below the whole length of the arch A A, terminating at both ends in a grate, whence the heat is conducted to the middle of the arch, but also freely escapes along the whole length into the space A by the several flues gg cut in the sides. These flues are farther apart in the neighbourhood of the grates, but are 694 EFFECT OF MOISTURE IN FUEL. aiore numerous towards the middle, so as to spread the heat more equably. The fires ccc are arched over for a short distance above the two grates ; farther on, and towards the middle, they are covered with sheet-iron. Fio. 606. A-bove is a railway a a a, upon which the iron barrows travel, containing the fuel to be dried. The iron plates prevent the flame from igniting the contents of the barrows, each of which contains about two stacks of wood ; there are nine barrows in every arch A, and the whole charge is dried in thirty-six hours. Although water has thus been shown to diminish the effect of fuel, this is not invariably the case under all conditions, and a contrary result appears to be produced when the water is brought into contact with the fuel in the gaseous state. The experiments of Bunsen and Fyfe have shown that red-hot coal and aqueous vapour mutually decompose each other into hydrogen and carbonic oxide (with some carbonic acid), both of which, if sufficient oxygen be present, burn with the production of considerable heat to form water and carbonic acid;* numerous observations showed further, that the additional heat evolved more than compensated for the fuel employed in producing the vapour. If, therefore, sufficient air be present with the vapour to burn the gases which are formed, the vapour will be of service, producing a greater amount of heat and a more lively combustion. The moment, however, that the vapour exceeds the proper proportion, and the supply of air is thus diminished, the temperature rapidly sinks, so that the fire is often totally extinguished. It is probable that in these " observa- tions," which appear to have been calculations, and not experimental results, •Messrs. Bunsen and Fyfe did not take into account the heat absorbed or rendered latent in the dissociation of the steam used, or the specific heat of the water-vapour re-formed on the combustion of the hydrogen. Their estimate of the available heat is thus too high. It may be observed that the brightness of the flame produced with steam often leads to the conclusion that it is a hotter flame than it is actually found to be on examination. A common practice is to place a vessel with water under the grate of ♦ One part of coal, bnmiDg, surrounded by vapour, first to carbonic oxide and then to car- bonic acid, heats 78.15 of water to 100°; 0.1666 part of hydrogen is liberated at the same time, which, in burning, heats 39.5 parts more water. The advantage gained, therefore, is = Z2i?S -_ 1 supposing the combustion of coal in aqueous vapour to be attended by the 78. 15 +39.'; same heating phenomena as in ihe air. RELATIVE VALUES OF FUEL FOK WARMING. 695 the furnace, so that the heat radiating downwards may cause evaporation without cost. In steam-engines, a portion of the vapour which has been used may be conducted at once to the fire, instead of being condensed. An addition of water to the fuel causes so great a depression of temperature while the water is being converted into vapour, that the decomposition of the aqueous vapour can no longer be effected, and the practice, which is not unfrequent amongst consumers of coal, is therefore not economical. Practical experiments, instituted by the Frankfort Society for the Improvement of Arts and Manufactures, have also clearly proved the practice to be bad. A moderate moistening of small coal has, however, the advantage of prevent- ing its falling through the grate-bars and creating dust, for it cakes together and becomes more solid by being moistened ; it also gives niore ilame. It is still better to add about ^th. of m.oist clay for the same purpose, which, being disseminated throughout the mass of the coal, aifords greater access to the air, and the heat absorbed by the clay, being slowly evolved, acts with more advantage. The experiments made by the Frankfort Society have shown that small coal mixed with clay was even better than small coal alone. When moist wood is so closely heaped together that the air cannot pass freely through, a change quickly follows, which is accompanied by the almost entire destruction of its combustibility ; this change is . really originated by minute living organisms. It is well known that the dead wood in the centre of old trees (where moisture, but little air, has access) becomes changed into a white, soft, phosphorescent substance, which, when ignited, burns slowly without flame, like tinder, evolving very little heat. During this mouldering process, the weight of the wood has undergone greater change than the relative proportions of its elements. A specimen contained, for instance, 47 per cent, carbon, and with 6 per cent, hydrogen only 45.3 per cent, oxygen; this greater proportion of hydrogen than in fresh wood would tend to increase the inflammability of the substance if it were not already chemically combined to form water, a supposition fully borne out by the properties of the substance. Wood thus changed is said to have undergone dry rot. The heating value of combustibles obtained by careful experiment and calculation is of great importance as a control in estimating the beneficial practical application of fuel, and an indication of what may be obtained. The difficulties in the way of perfect combustion, however, are so numerous and varied in their source in the different methods of employing fuel, that no estimation of its value for any particular object can be accurately determined by one method. It has consequently been found necessary to ascertain by direct experiment the relative value of combustibles in the various kinds of grates, fire-places, boUer-fires, &c., which they are intended to supply. With reference to the warmiag of dwellings, it was found in a series of experiments — in which the external temperature varied from + 6.8° (44° F.) to —6.2° (21° F.), and the air of the room had a mean temperature of 15° to 19° C. (S9° to 66° F.), while the smoke escaped by the chimney at a temperature of 75° to 100° 0. (167° to 212° F.) — that 100 lbs. of air-dried cleft beech wood efifect as much as 48 lbs. of pit-coal, 40 (the smoke being cooled as much as possible) to 60 lbs. of mixed small coal moistened with Jyth of water, 44 lbs. of bituminous small coal with jV*^ water, 3 7 lbs. of small coal with yV*'^ water and ^th clay, and 38 lbs. of small coal with Ath water and ^th clay. The observed temperature of the air was a mean, existing at an equal distance from the floor and ceiling of the room. The observations prove, that the temperature of a room, after equilibrium has once been established, is highest at the top, and increases for equal distances from the \continued on p. 702.] 696 CHAEACTEE AND ErFICIENCY OF AMEBICAN COALS. GENERAL SYNOPTICAL TABLE OP THE CHABACTEB AND ■s i. j3 Designation 6f Coal. 1 S 1 It go a. .J 11 II 1' a. H II is 1 1 h i ■g. u fi & i i 1 Si || i§ u § 1 1 8 i 1 1 8 e- i 1 /B^nver Meadpw, slope K'o. 3 Pa. I.610 100.645 54-93 0:^46 40.78 2-38 88,94 7.110 Beaver Meadow, slope No. 5 Pa. I -55 1 96.930 56-19 of 80 39-86 2.56 91.47 5150 S Forest Improvement . . Pa. 1477 92.310 53-66 0.581 41-75 307 90-75 4.410 1 Peach Mountain . . I'a. 1.464 91.510 53-79 0.588 41.64 2.96 89.02 6.130 SO Lehigh . . . .Pa. >S9o 99-390 55-32 0-5S7 40.50 S.28 89-15 5.560 "S Lackawanna . . . Pa. 1.421 88.840 48.89 0-550 45-82 3-91 87.74 6.350 < Lyken's Valley . . . P.i. 1.389 86.820 48.56 0-559 46.13 6.88 83.84 9.250 Beaver Meadow (navy yard) Pa. iNatnral cokn of Virginia . Va. — 55-08 40.65 — 8.100 1-323 82.700 46.64 0.564 48.03 12.44 75.08 11.830 Coke of Midlothian co*l . Va. — 32.70 68.50 16.550 Cuke of Neff's (Cumberland) coal .... Va. — — 31-57 — 70.95 — — '3-340 Mixtnre, one-fifth Midlothian and four-fifths Beaver Meadow . — — 54-29 41.26 8.880 Mixture, one-fifth Cumberland and four-fifths Beaver M -adow — — 54-5' — 41.09 8.i8o 'New York and Maryland Mining s Company's . . . Md. Neff's Cumberland . . Mil. 1-43" 89.440 S370 0.600 41.71 12.31 73-50 12.400 1-337 83280 54-29 0.652 41.26 12.67 74-53 10.340 3 Easby's "Coal-in-Store" . Md. 1-307 81.690 53-47 0-655 41.90 14-98 76.26 8.080 3 Atkinson and Templeman'a Md. 1-313 82.090 52-92 0.645 42.33 15-53 76.69 7-330 s Basby and Smith's . . Md. 1-332 83.260 51.16 0.614 4378 15.52 74-29 9.300 a Cumberland (navy yarti) . Md. 1.414 88.403 53-29 0.603 42.04 14-87 70.85 14.980 Dauphin and Susquehanna . Pa. '•443 90.190 50.54 0.560 44-32 13-82 74-24 11.490 Bloaiburg .... Pa. 1-324 82.730 53-05 0.641 42.22 14.78 73" 10.770 W Lycoming Creek . . Pa. 1-388 86.740 55-38 0.638 40.45 1384 71-53 13960 s Quin's Eun . . . Pa. 1-331 83.220 50-34 0.605 44.50 17-97 72-79 8.410 & Karthaus .... Pa. 1.284 80.220 52-54 0.655 42.63 19-53 73-77 7000 •Cambria County . . Pa. Barr'a Deep Eun . . Va. Ml Crouch and Snead's . . Va. 1.407 87.840 53-46 0.608 41.90 20.52 69-37 9.150 1382 86.410 53-17 0.615 42.13 19-78 67.96 10470 1.451 90.710 53-59. 0.591 41.80 24.38 59.98 14.280 Ua Midlothian (900 feet shaft). Va. 1-437 87.500 50-52 0.577 44-34 27.28 61.08 10.470 ^ Q Greek Company's coal . Va. 1-319 82.480 46.50 0.564 48.17 32-47 60. -^o 8570 S Clover Hill " . . . Va. 1.285 80.360 45-49 0.566 49-25 32.21 56.83 10.130 1 Chesterfield Mining Co.'s . Va. 1.289 80.570 45-55 0.565 49.18 32-63 58-79 8.630 P 'a 3 Midlothian (average) . . Va. 1.294 80.900 54-04 0.568 41.45 29.86 53-01 14-740 Tippecanoe . . . Va. 1.346 84.140 45-10 0.536 49-67 34-54 54.62 9370 m Midlothian f" new shaft "). Vii. Midlothian (screened) . Va. 1.32s 82.820 47.90 0.581 46.76 35-77 56.40 9-140 1.283 80.210 45-72 0.570 48-99 34-70 54.06 9.660 ^Midlothian (navy yard) . Va. 1.390 86.860 54-47 0.627 41-13 29.12 56.11 14.140 Pictou (from New York) N.S. 1.318 82.350 53-55 0.650 41.83 27-83 56.98 13-390 Sydney . . . N.S. 1-338 83.660 47-44 0.567 47.22 23.81 67.57 5.490 i Pictou (Cunard's) . N.S. 1-325 82.830 49-25 0-595 4548 25.97 60.74 12.510 a Liverpool . . Eiig. 1.262 7CS.890 47-88 0.607 46.78 39-96 54-90 4.620 1 Newcastle . . Dng. I.2S7 78.540 50.82 0.647 44.08 35-83 57-00 S.4C0 Scotch . . , Scotland 1. 519 94-950 5 '-09 0.538 43-84 39-19 48.81 9-340 (^ Pittsburg . . Pa. 1.252 78.370 46.81 0598 47-85 3676 54-93 7.070 Cannellon . . Ind. 1-273 79540 47-65 0-599 47.01 33-99 58-44 4.970 \Ury piue .rood . . . . • ~ 21.01 106.62 0.307 CHAKACTEK AND EFFICIENCY OP AMERICAN COALS. 697 EFFICIENCY OF THE AMERICAN COALS. i 8 « Is si •3 1 § 1 1 li gs. ft C K 1" > >> il h ^1 1 ^ SI il P 1 u "3 ji CO* 3 J- II £| i DQ il il |i 11 " 1 It ill It if ^3 o'a «--2 1 « t- i£ 0, I2.S7 h £ 505.5 t* < m 37.31 3944-5 6.69 3-87 8.20 9.21 11.960 I.OI 112.4 32.41 10.462 25-36 4250.5 6.27 2.42 10.66 8.76 988 556.1 6.740 0.60 61.2 33-29 10.592 2975 3810.0 ti' 3-32 12.89 8.92 10.06 440.8 6.970 0.81 40.2 33-39 10.807 3009 7371.9 6.69 3-54 14.04 8.96 lO.II 545-7 6.970 3-03 26.6 33-49 10.871 16.87 3838-2 6-95 327 11.63 7-73 8-93 494-0 7.220 1.08 36.1 28.92 9.626 2313 4112.5 6-45 2.67 11.92 8.56 9-79 477-7 8.930 1.24 57-2 33-53 10. 764 12.34 2471.0 6.92 2.63 12.89 8-43 9.46 459-6 12.240 4-40 18.0 32-60 10.788 — 1S97-3 4-63 5-08 9-42 7-86 9.08 500.0 8.100 1.40 107.1 1 — 9.881 6.27 4209.0 8.15 1-74 12.56 7-47 8-47 395-3 18.460 5-31 60.9 32.49 10.389 1037.0 9.64 2.00 16.50 7.40 8-63 282.6 16.540 10.51 53-2 10.343 — 994-2 8.43 1. 17 14.91 7-85 9.00 284.0 13-340 3-55 43.7 — 10.381 — 2050.0 5-83 3-21 10.06 7.69 8.86 481. 1 8.880 4.91 9 5 — 9-725 — 2074.0 7-97 2.25 12.81 7-97 9.18 498.5 8.180 3-09 16.0 — 9-997 5-97 2127.7 6.28 1.33 12.79 8.65 9-78 524.8 12.710 5-43 10.1 30.33 1 1.208 5.88 4318.4 7.86 1.68 14.80 8.19 9-44 512.7 10.960 4-53 6.1 30.72 10.604 S.09 1 158.0 6.04 1-75 12.73 8.88 10.02 535-6 8.380 1-33 18.2 32.69 10.935 4-94 2318.2 7-33 0.99 15-70 9-47 10.70 566.2 7.960 2.12 5-1 30.06 11.624 4-79 4474-5 8.02 1-52 14-97 8.69 9.96 511.1 9.690 3-04 5.3 3301 11.034 5.00 — — — — — — — 14.530 2.29 13.5 27-98 5.37 2557.0 6 86 0.83 13-35 8.31 9-34 472.8 16.360 3-50 23.7 31.18 11.171 49'; 4295-0 7-77 0.84 15-67 8.64 9.72 5'5-9 11.200 3-40 13-7 32-54 10.956 S.18 3P73-2 6-33 1.72 12.13 7.92 8.91 493-3 16.920 3-26 46.2 32-89 10.724 4.05 1883.2 7.29 0.75 13-90 9.08 10.27 517-0 8.940 I-31 •4-7 30.90 11.275 4.11 3643-8 6.66 1.87 12.48 7-92 9-09 477-4 7.890 3-66 52.5 33-31 9.8^7 3.66 3488.5 6.68 2.00, 12.47 8.04 9.24 486.9 9-750 3-48 14.8 31.46 10.239 3.43 5072.7 7.60 1.52 13.42 7.84 9.02 478.7 11.070 4-78 6.4 28.01 10. 142 2.50 3834-7 Hi 1. 16 11.65 7-30 8.34 445.0 14.340 5-37 6.0 25-77 9.740 2.24 3417-5 8.68 1.38 14-51 7-50 8.58 403-7 10.700 6-47 5-9 26.99 9.611 2.03 3769-6 8.59 1. 17 14-88 7-44 8.42 391-8 8.640 4.41 10.5 30-52 9.211 1.79 ^m-^ 5-84 1-93 8-35 6.71 7.67 347-4 10.600 3-86 II-5 28.53 8.588 1.92 3876.0 8.46 1. 17 14-47 7-95 9.00 410.9 9.070 4-19 10.5 27-38 9.896 1.78 4506.4 6.68 152 to.o8 7-30 8.29 448.5 14.830 8.82 6-4 29.03 9.741 1.60 4904.7 7-37 1-33 10.62 6-74 7-75 3502 9.720 4-03 11.2 29.17 8-583 1.68 2918.S 7.60 0.91 13.46 7.66 8.76 418.6 10.260 4-21 17- 1 26.80 9-751 1.57 4132.0 6.24 1.29 10. 1 1 7.84 8.94 408.7 10. 270 3-33 14.8 29.74 9.970 '■95 1463-5 — — - — — — — — 4.42 43-2 28.23 2.11 4153-9 7.84 0.94 12.79 7-48 8.41 450.6 13370 6.13 5-7 28.18 9.710 2.84 1601.1 8.31 1. 18 13-85 7.01 Z-99 378-9 6.010 2.24 5-9 29.15 8.497 2.59 1962.5 9.84 0.85 16.47 7-45 8.48 417-9 12.060 6.19 3-7 26.69 9-648 1.51 3786.0 8.59 0.86 13-43 ^■fl 7-48 375-4 5.040 1.86 11.1 27.88 8.255 1.60 4023.0 8.03 0.84 13-75 7.68 8.66 439-6 5.680 314 10.7 27.55 9.178 1.26 3860.0 10.74 0.96 14-32 6.14 6-95 353-8 10.100 5-63 5-7 27.00 7719 2.01 208.4 — — 10.56 7-03 8.20 384.1 8.250 0.94 9-9 28.89 8.942 1.72 2465-5 11.09 0.50 15.05 6.31 7-34 348.8 5.120 1.64 6.4 26.53 7-734 2360.5 15-87 13.86 4.06 4.69 98.6 0.307 4-707 698 ECONOMIC VALUES OF WELSH COALS. ADMIRALTY INVESTIGATION. ECONOMIC VALUES OP THE WELSH COALS. Names of Coals employed in the Experiments. B 11* 1 Si "J 11 i It n ■3 "oil ■Sog ■s-i ^ c MS D. H m II ii 1 = 1 G. ■3 d 3 1 iff n H. ■g y 1 - A. B. c. E. F. I. K. Ihfl. lbs. lbs. Mean. Aberaman Meithyv . 10.75 48.900 81.910 •597 67.500 45.800 — — 525-67 Ebbw Vale . 10.21 53-300 78.810 .676 45980 42.260 45.0 10.64 544-19 460.22 Thomas's Merthyr . 10.16 53.000 82.290 .644 55.260 42.260 57.5 10.72 538.48 520.80 Duffrya . 10.14 53.220 82.720 643 55-430 42.090 56.2 11.80 540.12 409-32 Nixon's Merthyr 9.96 51.700 82.290 .628 59.160 43-320 64.5 10.70 614-93 511.40 Binea 9-94 57.080 81.357 .702 42-530 39.240 51.2 10.30 587-92 486.95 Bed was . 979 50.500 82.600 .611 63-565 44-320 54-0 9-99 494-39 476.96 HiU'S-PlymouthWoik 9-75 51.200 84.780 .603 65.680 43-740 64.0 10.18 499.20 531.60 Aberdare Company's Merthyr 9-73 49.300 81.730 .603 65.780 45-430 74-5 10.27 479-68 489.50 Gadly's 9-feet Seain 9.56 54.800 83.160 .658 5J-750 40.870 76.0 10.46 52388 517-30 Eesolven 9S3 58.660 82.354 .712 40.390 38.190 35-0 10.44 559-02 390.25 Mynydd Newydd 9-52 56-330 81.730 .689 45.090 39-760 53-7 10.59 536-26 470.69 Abercam 947 50.300 83.220 .604 65.440 44-530 54-5 9-63 443-96 480.00 Anthracite, Jones & Co. . . . 9.46 58.250 85.786 .679 47.260 38.450 68.5 9-70 565.02 409-37 Ward's Fiery Vein . 9.40 57-433 83.850 .685 46000 39.000 46.5 10.60 608.78 529.90 Neath Abbey . 938 59.300 83-570 .709 49.920 37-770 50.0 9-65 556-23 546.10 Graigola . 9-35 60.166 81.107 .742 34.800 37-230 49-3 9.66 581.20 441.48 Gadly's 4-feet Seam 9.29 51.600 82.790 .623 60.440 43410 68.5 10.73 479-36 400.00 Machen Rock Vein . 923 48.106 80.910 ■594 68.210 46.560 52.5 9-43 44396 488.75 Birch Grove, Graigola 9.22 51.000 84.850 .601 66.370 43.920 59.0 9-64 470.22 507-50 Llynvi . 9.19 53-300 80.350 .663 50.560 42.020 — 9.58 429.82 399-50 Cadoxton 8.97 58.100 85970 .675 47-960 38-550 — 9-07 521-15 344.16 Oldcastle Fiery Vein 8.94 50.916 80.420 •633 57-946 43-990 57-7 455-18 464.30 Vivian and Sous' 8.92 47.900 81.040 .591 69.180 46.760 54.0 9-11 427.26 421.25 Llangennech . 8.86 56-930 81.850 .695 43.760 39-340 53-5 9.20 523-75 373-22 Three-quarter Eock Vein . 8.84 56.388 83.600 .674 48.260 39.720 52-7 — 498.46 486.86 Pentrepolh 8.72 57-720 81.730 •705 40.170 38.800 46.5 8.98 518.32 381.50 CwmFrood Rook Vein 8.70 55-277 78.299 .706 41.648 40.520 72.5 9-38 480.90 379.80 Cwm Nant-y-Gros . 8.42 56.000 79-859 .701 42.600 40.000 55-7 8.82 471-52 404.16 Brymbo Main . 8.36 47.000 81.100 •579 72-550 47.650 8.56 392.92 435-83 Vivian and Sons' Eock Vawr . 8.08 48.900 81.160 .602 65.970 45.800 70.5 8.19 395-" 452.50 Coleshill . 8.00 53-000 80.483 .658 51-850 42.260 62.0 8.34 424.00 406.41 Brymbo Two-yard . 7.8s 47.900 80.040 •|g^ 67.110 46.760 79-5 7.91 376.00 441.66 Eock Vawr 7.68 55.000 80.210 • 685 45-830 40.720 65-5 7.88 422.40 397-50 Porth-mawr . 7-53 53-300 86.722 .614 62.700 42.020 62.0 7-75 401.34 347-44 Polity pool 747 55.700 83-350 .676 47-845 40.216 57-5 8.04 416.07 250.40 Pentrefelin 6.36 66.166 84.726 .781 28.051 33-850 52.7 7.40 489.62 247.24 ECONOMIC VALUES OP NEWCASTLE AND DERBYSHIRE COALS. 699 ECONOMIC VALUES OP THE NEWCASTLE COALS. Names of Coals employed 1 1^ si ■si r Cent, between nd Economical ights. 4 111 ■3 « i 13 g.5 1 y fit in the Experiments. CT3 g .SS 11 II Is. ■3£S Hi PI ft J? f'i 1 " |«2 ^ •3 ' w 2H Ij K gl g B 5 a H. $ 1 A. B. C. D. E. F. a. I. K. lbs. lb«. Iba. Jlti.n. AVillington 9-95 S3- 2 79.870 .666 50.13 42.10 43-0 10.16 529.34 Andrews House Tan- 1 field . 9-39 52. 1 78.860 .660 51-36 42.99 — . 9.80 489.21 351.20 Bowden Close . 9.38 50.6 79.870 -633 57-84 44.26 38-5 9.67 47462 Haswell Wallsend . 8.87 47-4 80.230 -59° 69.26 47-25 73-0 9.07 420.43 411.66 Newcastle Hartley . 8.23 SO- 5 80.270 .629 58-95 44-35 78-5 8.65 415.61 308.00 Hedley's Hartley . 8.16 520 81.790 -635 57-28 43-07 85-5 8.71 424-32 300.80 Bates' West Hartley 8.04 50.8 78.170 -649 53-89 44-13 695 8.26 408.43 406.80 West Hartley Main 7.87 48.9 78.860 .620 61.26 45-80 79.0 8.05 384.84 457.50 Buddie's West Hart- ley .. . 7.82 50.6 77.110 .656 52-39 44-09 80.0 8.01 39569 413.30 Hasfi'igs' Hartley . 7-77 48. 5 78.040 .621 60.90 46.18 75-5 796 376.84 404.50 Carr's Hartley 7-71 47-8 78.230 .611 63.66 46.86 77-5 8.13 368.53 344.30 Davison' sWest Hart- ley . North Percy Hartley 7.61 47-7 78-360 .608 64.27 46.96 76-5 7.83 362.99 402.90 7.57 49-1 78.290 .627 59-45 45.b2 60.0 7.72 371.68 423.5° Haswell Coal Cd.'s Steamboat Walls- end 7.48 49- S 79.360 .623 60.32 45-25 79.5 7.85 370.66 291.80 Derwentwater Hart- ley . . . 7.42 SO- 4 7^-7gS •639 56.32 44-44 63.5 7.66 373.96 451.10 Broomhill 7-30 52.5 77.988 .673 4855 42.67 65.7 7.66 38325 397.78 Original Hartley 6.82 49-1 77.980 .629 58.81 45.62 80.0 6.98 334-86 428.40 Cowpeh and Sidney's Hartley 6.79 47-9 78.670 .608 64.23 46.76 74.0 7.02 325-24 350.40 ECONOMIC VALUES OF CERTAIN DEEBYSHIBE COALS. Earl Fitzwilliam's Elsecar Hoyland & Co.'s Elsecar Earl Fitzwilliam's Park Gate . Bntterly Co.'s Port- land . Bntterly Co.'s Lang- ley Stavely . Loscoe Soft Loscoe Hard . A. 8.52 8.07 7.92 7.92 7.80 7.26 6.88 6.32 B. lbs. 47.2 48.2 47.0 47-1 47-8 49-9 44-8 45-9 C. lbs. 80.85 82.16 81.79 81.16 78.86 79-79 80.17 79.60 D. ■583 .586 .574 .580 .606 .625 .558 -576 E. 70-29 70.45 74.02 72.31 64-97 59-90 78-95 73-42 F. 47-45 46.47 47-65 47-55 46.86 44.88 50.00 48.80 G. 77-0 82.5 78.0 89.0 84-5 88.5 62.0 86.0 H. 8.78 8-43 8.24 8.04 7-98 7.40 6-99 I. lbs. 402.14 388.97 372.24 373.03 372.84 362.27 308 22 290.08 K. Mean. 412.70 372.91 393.75 487.08 398.69 466.20 499.06 431.42 700 ECONOMIC VALUES OF LANCASHIRE COALS.' ECONOMIC VALUES OF THE LANCASHIRE COALS. iu 4> S j si 11 .4 i-# i 1 1 1 Namea of Cuals employed ii? |i°2 s-t ■II 11 If f II -.3 13 g W ill 2 -• 1 g' ia the Experiments. f II ■2S| 111 P3 t PI •a '^ 1 " ■S £ A. B. lbs. c. D. 'E. F. G. H. I. Ibs.- K. .Mean. Ince Hall Co.'s Arley 9-47 47.6 79-36 -599 66.72 47-05 73-5 9-35 435'^o6 487-29 Haydock Little Delf 913 44.9 78.42 -572 74^65 49-88 66.5 9.26 409^93 532-91 Balcarres Arley 8.83 SO. 5 78.17 .646 54-79 44^35 76.0 9.09 445^91 454,10 Blaokley Hur.st 8.81 48.0 78.90 .608 64-37 46.66 65.0 9.00 422.88 500.80 Ince Hall Pemberton Yard . 8.78 48.0 84.10 .570 75.20 46.66 75-5 — 421.44 461.25 Haydock RiishyPark 8.74 49-3 82.54 •597 67.42 45^43 77.0 8.91 430^ 88 461.66 Moss Hall Pember- ton J'our-feet 8.52 47-3 78.48 .602 65.91 47^35 71-5 8.65 402.99 480.00 Haydock Higher Flo- rida . 8.39 49-5 75-99 .651 53-51 45-25 74.0 8-49 415^30 467.50 Ince Hall Pemberton Four-feet . 8.34 S1.8 79.60 .650 53.66 43-24 74-5 8.45 432.01 497^39 Blackbrook Little Delf . 8.29 51.0 78.16 .652 53-25 43-92 61.5 8.55 422.79 440.40 Kins . 8.17 50.8 81.10 .626 59-64 44.09 78.5 8.35 415^03 39S^4i Euehy Park Mine . Blackbrook Eusliy Park . 8.08 47-0 80.04 .587 70.31 47-65 67.0 8^35 379^76 419.10 8.02 SS-3 80.15 .689 44-93 40.50 80.5 8.26 443^50 481.20 Johnson and Wirth- ington's Eushy Park . . . 8.01 So.o 80.10 .624 60.20 44.80 69.0 8.16 400.50 454-50 Laffak Eushy Park . 7.98 52.6 84.07 .625 59-82 42.58 75-5 8.16 419-74 43S-0O Balcarres HaighYard ,7-90 50.8 80.10 -634 57-67 44-13 80.0 8.23 401.32 398.30 Haydock FloiiJa Main . 7-83 48.0 79.04 ■507 64.66 46.66 81.5 7-97 375-84 422.50 Wigan Four-feet . 7-77 S3-4 75-49 .707 41.36 41.94 75-0 8.0s 414.91 414-79 Ince Hall Pemberton Five-feet . 7.72 51.8 79.17 -654 52-83 43^24 71-5 7^95 399-89 495.20 Cannel (Wigan) Ince Hall Co.'s Fur- 7.70 48.3 76.80 .628 59.00 46^37 9S-0 8.06 37i^9i 381.10 nace Vein . 7-47 49-3 81.98 .601 66.28 45^43 71-5 7.84 368.27 435^21 Balcarres Lindsay . 7-44 Si-i 78.61 .650 53-83 43^ 83 70.0 7.58 380.18 43i^50 Caldwell andThomp- son's Eushy Park 7-34 47. S 79.29 •599 56.92 47-15 76.0 7-43 348.65 449-79 Balcarres FivB-feet . 7.21 49-0 79.11 .619 61.44 45-71 44-5 7^35 353^29 489-50 Moss Hall Pember- ton Five-feet 7- 13 48.3 80.04 .603 65-71 46-37 78-5 7.29 344-37 417.18 Moss Hall Co.'s New Mine . 7.04 48.4 79-73 .607 64-73 46.28 76.5 7.16 340-73 422.08 Caldwell andThomp- son's Higher Delf 6.85 48.4 79.48 .608 64.21 46.28 77.0 6.94 331-54 484.28 Johnson and Wirth- ington's Sir John 6.32 S1.6 81-73 .631 58-39 43-41 82.0 6.62 326.11 362.70 ECONOMIC VALUES OF VAEIOUS COALS. 701 ECONOMIC VALUES OF VAHIOUS COALS. Names of Coals employed in the Eiperiments. IK A. 1 if 1 "o a H 1 II OH si V g fi 111 ill H > Ed 1 . u Pi 1 1 s & s .2p p. Ml ■s t s a a: B. c. D. E. F. G. H. I. K. lbs. lbs. Mean. 'Wallsend Elgin . 8.46 54.60 78.611 -694 43-780 41.02 64.0 8.67 460.82 435-77 Well-wood 8.24 52.60 79.780 .659 53-570 42.58 80.0 8.39 433-42 438.50 f^ Dalkeith Coronation 1 Seam . 7.71 51.66 78.611 -657 52.170 43-36 88.2 7.86 398.29 370.08 s Kilmarnock Skei- 1 ' ■s rington 7.66 44.70 77.420 •577 73-19° 50.11 635 7.82 342.40 470-83 Fordel Splint . 7.56 55.00 78.611 -699 42.920 40-72 63.0 7.69 415.80 464.98 di Grangemouth 7.40 54-25 80.480 .674 48-350 40.13 69-7 7.91 401.45 380.40 Egliriton 7-37 52.00 79.840 .651 51 480 43-07 79-5 7.48 383-24 406.20 \Dalkeith Jewel Seam 7.08 49.80 79.672 .625 59-^84 44.98 85-7 7.10 352-58 355-18 Slievardagh Irish An- thracite . 9.85 62.80 99-57° .630 58-55° 35.66 74.0 10.49 618.58 473-18 .0 ColeshillCo.'sBagiUt g Main . 8-33 49.60 79.170 .626 59.610 45.16 79.0 850 413-16 461.25 'g" Ewlowe 7.02 50.40 79-54° •633 57.810 44.44 84.0 7.16 353-8° 363-95 > Ibstock . 6.91 47-3° 80.540 .587 70.270 47^35 62.0 7.02 326.84 45416 Lydney (Forest of Dean) 8.52 54-44 80.046 .680 47.020 41.14 S5^o 8.98 463.86 487-19 Conception Bay, Chili . 5-72 80.540 — — — 5.96 425.00 (Warlich's Patent BD Fuel . 10.36 69.05 72.248 •955 4.490 32-44 — 10.60 715-35 457-84 Livingstone's Steam 1 1 Fuel . . . 1 10.03 65.60 73-860 .888 12.590 34^14 — 10-57 657.96 483-95 il Lyon's Patent Fuel 9S« 61.10 74-73° .817 22.300 36.66 — 9-77 585-33 409.10 s Wvlam's 8.92 65.08 68.629 -948 5-450 34.41 — 9-74 580.51 418.89 PL, Bell's . 8-53 65.30 71.124 .918 8.910 34-30 — 8.65 557.00 549-11 [ Holland and Green's 7-59 64.80 81.230 -797 25-3501 34-56 — 7-86 491-83 470.00 AVERAGE VALUE OF COALS FROM DIFFERENT LOCALITIES. u & S Localitr. III SI'S 1^- 11 I- u la n ^.1 J3 1 Hi ■S^'S 1 i il ^^^ ^ = s a •SI S 3 •S-Sl E£i ■si fn^ i -ds =■5* li P3 ^ s |°- £ A. B. c. D. E. F. Average of 37 samples from Wales 9-05 448.2 53-1 42-71 60.9 1,42 17 „ Newcastle 8.37 411. 1 49-8 45-30 67-5 0.94 28 „ Lancashire 7-94 447-6 49-7 4515 73-5 1.42 8 „ Scotland . 7.70 431-4 50-0 49-99 73-4 1.45 j» 8 „ Derbyshire 7-58 4327 47-2 47-45 80.9 1. 01 702 EFFECT OF COAL UNDER BOILERS. bottom, very nearly in geometrical progression, although the quotient is not the same under all circumstances. In one case it was found to be = 1.0727, when the temperature increased as follows : — floor, 18.36 ; at 2 feet, 18.36 X X.072; 4 feet, 18.36 X 1.072^; 6 feet, 18.36 x 1.072', &c. The action of coal under steam boilers has been examined by Fyfe, who believed that the heat actually made available from coal in practice, is nearly the same as ought to be produced, according to theory, by the quantity of coke which it yields. If coaj produces 50 per cent, of coke, for example, then 100 lbs. of the coal would boil 50 x 78.4 lbs. (Despretz) of water. According to Fyfe, i lb. of Scotch coal from Tranent wUl convert 5.61 lbs. of water into vapour from 0° 0. ; i lb. of the coke from this coal will boil 7.4 lbs. of water; i lb. of coal from Tranent yields 0.525 lb. of coke, which will consequently produce 3.9 lbs. of vapour, so that by carbonization there is a loss of heating power equivalent to 5.61 — 3.9 =1.71 lb. of vapour. In other experiments, the results with coal were 5.8 and 6.6, and with coke between 7.8 and 8.7. The greatest effect ob-served by Parkes was 8.68 lbs., and by Henwood, 9.96, with i part of the best Newcastle coal. The difierence in the amount of steam capable of being raised by coal from different localities, together with many other important physical properties upon which the economic value of this fuel depends, induced the Government of the United States to institute a series of practical experi- • ments on the coal of different districts, with a view to ascertain tlje relative values of the different varieties, more particularly for generating steam and forging iron. The entire investigation was entrusted to Professor W. E.. Johnson, and the results were published in a Report to Congress in the year 1844 (pp. 696, 697). The importance of such an investigation in connection with the wants of the steam navy and various branches ' of national industry, led to a similar undertaking by the Government of Great Britain, whicb was superintended generally by Sir Henry de la Beche and Dr. Lyon Playfair, whose several Reports to Government were concluded in ::S5i. The principal points to be looked for in steam fuel are thus stated by the British Commissioners : — 1. The fuel should burn so that steam may be raised in a short period, if this be desired ; in other words, it should be able to produce a quick action. 2. It should possess high evaporative power, that is, be capable of con- verting much water into steam, with a small consumption of coal. 3. It should not be bituminous, lest so much smoke be generated as to betray the position of ships of war when it is desirable that this should be concealed. 4. It should possess considerable cohesion of its particles, so that it may not be broken into too small fragments by the constant attrition which it may experience in the vessel. 5. It should combine a considerable density with such mechanical structure that it may be easily stowed away in small space ; a condition which, in coals of equal evaporative values, often involves a difference of more than 20 per cent. 6. It should be free from any considerable quantity of sulphur, and should not progressively decay, both of which circumstances render it liable to spontaneous combustion. The results of these very extensive series of experiments are contained in the Tables given at pp. 696-701. The following analyses and table of tests carried out at Portsmouth Dockyard give a comparative view of the quality and evaporative power of RESULTS WITH SCOTCH AND WELSH STEAM COALS. 703 Scotch steam coal from the Slamannan district, as against those of specimens of the best Welsh steam coals :— Chemical analysis by Dr. Wallace, of Glasgow, of a sample of steam coal, No. I, from Longrigg Colliery, of Messrs. James Nimmo & Co. Volatile matters ■ Coke Gas, tar, &o. Sulphur . Water, at 212° Fixed carbon Sulphur . Ash 17.21] 0.33 \ 19.92 2.38) 76.82) 0.41 [ 80.08 2.8s) 100.00 cwts. qr. lbs. Coke, per ton of coal, 1,794 lbs., or. • • 16 o 2 Specific gravity i .304 Weight of a cubic foot in pounds ... 0.81 Space required for storage, cubic feet per ton . . 41^ Heating or evaporating power, ^acticm, in pounds of water at 212° F., evaporated by the combustion of i lb. of coal 10.52 lbs. This is a steam coal of remarkably fine quality. It gives a very high heating or evaporating power, and contains a very moderate proportion of ash and sulphur. It gives comparatively little flame and practically no smoke. This coal compares very . favourably for navigation steam purposes with the best description of Welsh coal. Comparative analysis of eight of the most renowned of the Merthyr and other steam coals from South Wales, and four of the bes'; Scotch steam coals from the Slamannan district. The Welsh coals mentioned are those which stand highest in order of merit in a report of trials made at the Portsmouth Dockyard. The results from the Scotch coals are those obtained either by Govern- ment Dockyard trials or special analysis by renowned chemists. WELSH STEAM COALS. Nixon's Navigation Waynes Merthyr Thomas ,, Nauhudyn ,, Ynsfaio „ Merthyr Dare Eesolven Merthyr Insoles ,, Lbs. of Water Percentage evaporated by of lib. of Coal. Clinker & Ash . 10.05 S-37 . 10.05 S-37 • 9-79 S-47 9.62 5-48 ■ • 952 6.76 • 9-45 5-48 • 9-41 6.04 • 9-37 6.52 Average evaporating power . Average percentage of clinker and ash . 9.65 SCOOXIH STEAM COALS. Broadrigg West Longrigg . Eoughrigg . Longrigg ... Average evaporating power . Average percentage of clinker and ash Lbs. of Water evaporated by I lb. of Coal. . 10.21 • 10.03 10.00 ■ 956 9-94 S81 Percentage of Clinker & Ash. 2.52 4.00 2.99 377 332 704 TRIALS OF STEAM COALS. a < o < (I >■ -IS » M PS O Si o b O Ed O & O en •punnj at ?qj(neja .e""° a> S=S JO s^Dnpojj snoasBO \o m *3 m *| S "S am uo papuadxa j^an ZS^ , am iq aiqrauodBA CO w t^ On ro 00 >o giS ^ M " •^ •^ •^ M ■J o° 'S „ 25 s 1 "1 00 ^ 00 00 00 ^ ro £ •»i!oa . aqi luoij pajEjodtjAa o OS O a-. 00 00 00 ro ro in 5; 5 en Si in NO in § diqtjsnqujo^ Jo ouo in suoiG uoqa^Q M M d d d On d aqj jo jOMOd 3AHiiJodiAa p3i^in»|E0 •^ M *^ ■^ CO 00 ON t>. ■* rl- Th 8 .» ■aa3oaj!N pm uagXxQ VO M vO ■* 1 'S « d d r^ .£■,0 0,2 *^ ^ •^ ^'^ 3 . =-3isi- •; o o. VO 00 1^ rn ;eA late Pan bust atte •aa3oipfH £• OS >§ NO NO 1 5'S "o in lo lA ^ in VO* u-i O t^ m « m i-n M m ov in ro 5 •uoqwo Q\ O M o. ro 1 ro ■ 0* 00 in 6 1 « « « ro n "S g •mqdins 8 1 ■* m 1 1 1 1 M M d a fOSi Moiaq panadxa ajn;Eio|v 8 Th NO in VO S, 1 o r^ OS •«d- N fO •-; 1 d d M " '-' -'* r^ *^ 1^ OS 6 •fliiEjg agiMdg 1 00 00 ON ro 1 -=3 i; bb ^ •tS p^ f^ > c 1— 1 d > S 'E "3 73 -o s r° a B U :d a w Q. U ,;S ^ "2 o o « § a A 09 (^ . "5 m ^ at n .2 f2 09 B 1 S > < 'b ■*=; S •s > e |3 J2 o § !» s S5 O 02 o s« 5 „ o T? '*-< qj o 2 — '5'bb SD « & . a -&I S CD Bi I a * .9 g 2 F r t- 5 11 » -^ » sa s = & ^ <"«« S 5 ° 'Sag Mr ° E « ^ >< <^ 5 g-.S ^ a 25 £.3-3 S o o S g c — — ' a "S Ki-a P. ^il •S.l to ©OS ^ «Q c E^ S s « |£§- ^1" 3 " -S ea - a COALS USED IN AMERICAN TEIALS. 713 TABLK II. Hi g i^K Names of Coals employed in the S^S^ -el's !li1 gr^ CQ^ Experiments. ■5 1 = 5S- J Si 1 g ca Q ^U 2 y /Aberaman Merthyr 10.7s 320 §°-9° 83-55 7.39 Ebbw Vale . 10.21 32.0 89.78 76.00 13-78 Thomas's Merthyr 10.16 33-0 90.12 84.85 5-27 Duflryn . 10.14 30.0 88.26 81.04 7.22 Nixon's Merthyr 9.96 33.2 90.27 77-86 12.41 Binea 9-94 31.6 88.66 84.14 4-52 Bedwas . 9-79 28.2 80.61 64.76 '585 Hill's Plymouth Work . : 9-75 34-1 88.49 79.86 8.63 Aberdare Company's Merthyr . 9-73 34- • 88.28 82.57 5-7i Gadly's Nine-feet Seam 9.56 34-2 86.18 81.20 4.98 Resolven . 9-53 32.2 79-33 74-49 4.84 Mynydd Newydd 952 30.5 84.71 71-56 13-15 Abercarn 9-47 31.8 81.26 66.36 I4.C0 Anthracite, Jones and Co. 9.46 33-5 91.44 91-38 0.06 Ward's Fiery Vein 9.40 31-5 87.87 — — Neath Abbey . 9-38 31.2 89.04 57-87 31-17 JO Graigola . 9-35 32.1 84.87 82.26 2.61 a 'Gadly's Four-feet Seam . 9.29 34-2 88.56 83-35 5-21 - ( Maohen Kock Vein . 9-23 307 71.08 61.35 9-73 ■1 Birch Grove, Graigola 922 33-3 84.25 80.67 3-58 ^ Llynvi 9.19 32.2 87.18 69.90 17.28 Cadoxton 8.97 31-8 87.7- 78-43 9.28 Oldcastle Fiery Vein 8.94 31-4 87.68 77.16 10.52 Vivian and Sons' Mertlijr 8.82 31.0 82.75 61.79 20.96 Llangennech . 8.86 32.7 85.46 77-15 8.31 Three-quarler Rock Vein 8.84 26.6 75-15 51-54 23.61 1 Pentrepoth 8.72 31.2 88.12 79- '4 9-58 Cwm Frood Rock Vein . 8.70 28.3 82.25 62.80 19-45 ( !wm Nant-y-Gr08 . 8.42 29.7 78.36 60.00 18.36 Brymbo Main . 8.36 30-3 77.87 51.18 26.69 Vivian and Sons' Rock Vawr 8.08 30.0 7909 54-30 24.79 Coleshill . . ■ 8. CO 26.1 73-84 47-08 26.76 Brymbo Two-yard 7.8s 29 s 78.13 50.30 27-93 Rook Vawr 7.68 28.9 77-98 54-95 23.03 Porth-mawr . 7-53 24.8 74.70 48.38 26.32 j Pontypool 7-47 315 80.70 59.28 21.42 * Pentrefelin 6.36 30-5 85-52 78.91 6.61 '^Willington 9-95 31-3 86.81 71. II 15.70 Andrews House Tanfield 9.39 31-I 85.58 62.99 22.59 Bowden Close . 9-38 31-9 84.92 67.41 17.51 Haswell Wnllsend 8.87 31-5 83-47 62.50 20.97 Newcastle Hartley . 8.23 319 81.81 57-47 24-34 Hadley's Hartley . 8.16 304 80.26 63-19 17.07 _; Bates' West Hartley 8.04 28.9 80.61 5 West Hartley Mnin 7.87 30-3 8r.85 56-59 25.26 Buddie's West Hartley 7.82 29>S 80.75 — i; Hastings' Hartley . Carr's Hartley 7-77 28.6 82.24 32.66 49.58 X 7-71 30-9 79-83 55-42 24.41 ^ Davison's West Hartley . 7.61 30.1 82.26 53-65 28.61 'A North Percy Hartley Haswell Coal Company Steam-boat 7-57 29.1 80.03 53-96 26.07 Wallsend . 7.48 3I-S 83-71 55-45 26.26 Derwentwater Hartley 7.42 29.1 87.01 51. 10 35-91 Broorahill 7-3° 25-5 81.70 56-13 25-57 Oi-iginal Hartley 6.82 26.6 81.18 55-15 26.03 ^ Gowper and Sydney Hartley . 6.79 28.7 82.20 56.23 25-97 714 COALS USED IN AMERICAN TRIALS. TABLE I] — (contintied). "■S'-s -.bZ = 8 ■s-s-f . fl-^ Names of Coalfl employed in the ■gSa ^Iti Jill m Experiments. ih "3 1-1 = 1 § 00 5 HP ";2 GO / Earl Fitzwilliam's Elsecar 8.52 30.1 81.93 59-14 22.77 1 Hoylaud and Oo.'s Elsecar 8.07 29.7 80.05 58-77 21.28 6 Earl Fitzwilliam's Park Gate . 7.92 30.1 80.07 59-90 21.17 s Buiterly Co.'s Portland . 7.92 31.0 80.41 59-67 20.74 Butterly Co.'s Langley 7.80 30.0 77-97 50-25 27.72 aa Stavely . H^ 28.1 79- 8S 55-46 24-39 -s Losooe Soft 6.88 28.0 77-49 50.50 26.99 « ^LoscOR Hard ... 6.32 29.6 /Ince Hall Co.'s Arley . 9-47 32.5 82.61 62.47 20.14 Haydock Little Dl-U' 913 29-3 79-71 5468 25-03 Balcarres Arley 8.83 29.4 83-54 59-57 2397 Blackley Hurst 8.81 29.6 82.01 53-79 28,22 Ince Hall Pemterton Yard 8.78 30.0 80.78 58.26 22.52 Haydock Rushy Park 8.74 29.8 -77.65 55-72 21.93 Moss Hall Pemberton Four-feet 8.52 28. s 75-53 49.12 26.41 Haydock Higher Florida 8.39 29.7 77-33 48-05 2928 Ince Hall Pemberton Four-feet 8-34 28.8 77.01 56.01 21.00 Blackbrook Little Delf . 8.29 28.7 8270 54-17 2.8-53 King ... 8.17 31-3 73.66 5.3-68 19.98 ^ Rushy Park Mine . 80S 29.0 77.76 50.97 26.79 ii Blackbrook Rushy Park . 8.02 30-4 81.16 55-42 2574 Johnson and Worthington's Rushy s / Park ... 8.01 289 79.50 55-33 24.17 Laffak Rushy Park . 7.98 26 9 80.47 53-44 27.03 2 p3 Balcarres Haigh Yard 7.90 28.2 82.26 62.19 20.07 ^ Haydock Florida Main 7.83 29-3 77-49 52.38 25.11 Wigan Four-feet . 7-77 30.0 78.86 55-77 23.09 Ince Hall Pemberton Five-feet 7.72 28.7 68.72 42.16 26.56 Cannel (Wigan) 7.70 29-9 7923 55-49 23-74 Ince Hall Co.'s Furnace Vein . 7-47 28.6 74-74 54-36, 20.38 Balcarres Lind.say . 7-44 26.2 83.90 55-85 28.05 Caldwell and Thompson's Rushy Park 7-34 29.4 75.17 57.20 1897 Balcarres Five-feet . 7.21 26 74.21 46.69 27.52 Moss Hall Pemberton- Five-feet 7 13 27. S 76.16 50.08 26.08^ Moss Hall Co.'s New Mine 7.04 27.0 77-50 54-54 22.96 Caldwell and Thompson's Higher Delf 6.8s 28.4 75.40 48.25 27.15 \ Johnson and Wirthington's Sir John 6.32 23.8 . 72.86 44-75 28.11 / Wallsend Elgin 8.46 29.1 76.09 47-75 2834 ^ Wellewood 8.24 28.5 81.36 56.26 25.10 o 1^ Dalkeith Coronation S'eam 7.71 24.5 76.94 50.40 26.54 Kilmarnock Skerringtcm 7.66 30.3 79.82 48.05 31-77 Fordel Splint 7.56 79-58 48.03 31-55 o o Grangemouth . 7.40 28.5 79-85 5308 26.77 CQ Eglinton . 7-37 24-3 80.08 52. w 27.58 NDalkeith Jewel Seam 7.08 26.4 74-55 45-43 29.12 Slievardagli I"sh Antlivacito 9.85 30.1 8003 /'Coleshill Cd.'s Bagillt Main 8-33 26.1 88.48 54.18 3430 g Ewloe . 7.02 3I-I 80.97 50.87 30.10 .2 Ibstock . 6 QI 25- 1 74-97 44.81 30.16 y^ Sydney (Forest of Dean) . I Oonceplion Bay, Chili 8.52 26.0 5-72 25.8 ^ /Warlich's Patent Fuel . 10.36 315 90.02 g Livingstone's Steam Fuel 10.03 52-5 8607 « J Lyon's Patent Fuel t \ Wylam's 03 -^ ... 9.58 314 86.36 8.92 28.8 79.91 60.96 18.95 1 Bells . 8.53 28.5 87.88 66.74 21.14 ^1 \ Holland and Green's 7-59 23.7 70.14 COMPAEATIVE VALUE OF LITHARGE TEST. 715 If the average quantities of steam raised by coils which are capable of reducing the same amount of lead, be now compared, as shown in Table III., TABLE III. Steam generated by 1 Part of Coal. «M , fc. 1 liead reduced 1. 3 !,„■ s . S ^. 1 1. (S by I Part of Coal. = 1 6 ill fl il S .a S- $ sS: 1 s sS i E« u ^ h fes •«1 ^ ■5 h3 ■S Above 34 4 9.58 33-34 5 9.75 32-33 6 9.65 — — — — I 9-47 31-32 q 9.02 6 8.88 I 7.92 I ,8.17 30-31 5 9.07 4 7.84 3 8.08 3 8.19 I 7.66 29-30 2 8.13 2 7.69 2 7.19 9 8.32 2 8.00 28-29 3 8.72 3 7.80 2 7.07 8 7.88 2 7.82 27-28 — — — — 2 7.08 26-27 2 8.42 I 6.82 — — 3 7-54 I 7.08 25-26 — — I 7-30 24-25 I 7- S3 — — — — — 2 7.58 23-24 — — — I 6.32 it will be observed that although on the whole the amount of lead may be taken as an approximative test of the value of fuel, it can by no means be relied on as an exact measure of that value. The same may be observed with reference to the amount of fixed carbon as shown in Table IV. for differences of 5 per cent. TABLE IV. steam generated by i Part of Coal. t« Percentage ifl is 1 *«• 1 1. .- of Coke. Jl ,d •3 i 1 a s !5.i 1 S s 2 ^1 S 1 l.| > > > < < Above 90 80-85 9 9-74 75-80 b 9-43 70-75 2 9.52 I 9-95 65-70 2 9-34 I 9-38 60-65 S 8.95 3 8.81 — — 2 8.68 55-60 2 8.42 7 7.46 — 7-94 10 8.09 I 8.24 50-55 4 8.28 3 7.52 5 7-34 10 7-99 3 7-49 45-50 2 7.71 — — 2 — 4 781 4 7.(39 40-45 — — — — — — 2 7.02 30-35 — — I 7-77 The total amounts of carbon contained in the different coals classed together for every 5 per cent, of difference, and an average taken of the amount of steam raised from these, is shown in Table V., which, although it bears out the general fact of the carbon being in proportion to the steam raised, does not warrant the carbon being made an exact measure of the heating power. 7i6 RUSSIAN TRIALS OF SAGHALIEN COAL. TABLE V. Steam generated by 1 Fart of Coal tM t- g_ Total Percentage of Carbon, to 1 1^ is 1 li ill 1 £ t li el ■3 If .£3 > t- ij 3 < ■fl. ■< Above go 10.12 85-90 i.'> 957 3 8.92 80 85 6 9.19 14 7.84 4 8.10 9 9-39 2 7.80 75-80 7 8.39 I 7.71 3 7-31 14 7.92 5 796 70-75 3 8.25 — — 4 7.26 I 7.08 The Hessian Society for the Promotion of Arts and Manufactures ex- amined experimentally the value of wood, peat, and coal burnt under six different well-arranged coppers, and foUnd that i lb. of cleft beech wood, two years felled, converted 2.075 ^^^- "^ water from 0° C. into vapour, i lb. of peat evaporated 1.991 lb., and i lb. of small coal 5.201 lbs. of water. The following information regarding trials of Bussian coal is copied from " Engineering " of April 30, 1886 : — " Coal Experiments in the Pacific. — Some prolonged experiments with Pacific coal of various kinds, conducted by the naval authorities at Vladivostock, have yielded results of a very unsatisfactory character to Russia. The samples employed were obtained from the coal mines of Doue, on the island of Saghalien, from some newly-discovered' deposits in the province of the Amoor, from the adjacent country of Corea, and from the immediate neighbourhood of Vladivostock. Cardiff coal, as at present used by the Russian Pacific fleet, was accepted as the standard, and the question confided to the commission to solve was, whether any of the rival sorts obtained in the Pacific were sufficiently good to permit of Russia dispensing with the further use of the English article. The trials were very carefully conducted, and, according to the newspaper Vladivostock, the commission pronounced all the coals to be too smoky, and expressed the belief that for the present the Russian Pacific fleet could not do without Cardiff coal. This decision is very disappointing to those who had pinned their faith on the Saghalien coal mines, and is not very agree- able to the Russian Government. In 1878, when war between England and Russia seemed probable, the Russians, in default of supplies of their own, had to purchase at any price all the coal they could lay their hands on in Japan, at San Francisco, in Australia, and elsewhere, and after all their exertions, were able only to concentrate a very inadequate quantity at Vladivostock. Taught by experience, the Government set to work, as soon as the Treaty of Berlin was signed, to develop the coal deposits in Saghalien, an island which Russia had recently seized from Japan on account of its known supply of fuel. To Saghalien since then about 5000 exiles and 1000 troops have been sent, and probably the sum expended in settling them there and opening up the mines, which are further protected by batteries, has not been much under a million sterling. In spite of this outlay, when, last spring, the , English authorities bought up all the available Japanese coal, Russia again found herself provided with a limited stock of fuel, anf" that for the most part of an inferior quality. This has led to fresh activity in obtaining coal in the Amoor region and from Corea, but the outcome after all is that Russia finds herself compelled to continue her dependence upon Cardiff. Such a result is discouraging, even though the Vladivostock SCHEUEEK-KESTNEE'S EXPEEIMENTS. 7 1/. authorities consider that the Pacific coal is less to blame than the incapacity of the Russian mining engineers to work the proper kind of coal and send it in a fit condition to the market. When Donetz coal was first extracted in South Russia the same objections were expressed to its quality, yet the industry has annually increased year after year, and the quality is rapidly improving. In all likelihood, the same will be the ultimate result in the Pacific." By means of evaporative trials of various kinds of steam boilers, infor- mation has been from time to time collected as to the practical value of fuel. In 1858, the Industrial Society of Mulhouse instituted some trials which were carried out with diiferent designs of boilers worked under similar con- ditions. The results were reported upon by Messrs. Burnat and Dubied, who made careful investigations of the questions connected with the com- bustion of the fuel, as far as this could be done with the instruments for physical research which they had at command. Unfortunately, tliese results are not of much value, because they were not accompanied by analyses of the waste gases. They were also imperfect as regards measurement of the air supply used for combustion, and, in endeavouring to account for the utilization of the heat produced by combustion of the fuel, they exhibited a deficit of 20 per cent. The heat of combustion of coal had riot been ac- curately determined at the date of these trials, so that Messrs. Burnat and Dubied were guided by Dulong's law, and by his figures of the calorific power of carbon and hydrogen. Scheurer-Kestner began to investigate the subject in 1868, and has con- tinued his investigations down to the present day. A resumje of his re- searches was given by him in a paper read before tiie Societe Chimique of Paris, and is published in the Revue, Scientijique of February 18, 1888. The following particulars are quoted from the abstract of that paper Ln the Journal of the Society of Chemical Industry (September 1888, p. 615). Realizing that Burnat and Dubied's deficit of 20 per cent, "might proceed either from heat having in some way escaped unnoticed, or from an over- estimation of the heat of combustion of the coal, he made a threefold division of the problem, and set himself first to ascertain the quantity and composition of the products of combustion ; secondly, to determine accurately the heat of combustion of coal ; and thirdly, to repeat the ex- periments of Messrs. Burnat and Dubied, following their method, but with such modifications as might be suggested by the study of the composition of the gaseous products of combustion. " The composition of the gases arising from the combustion of coal had been studied before 1868 by men, like Ebelmen, whose names give a suffi- cient guarantee for the accuracy of their analytical results, but unfortunately the manner in which their samples were drawn precludes our attaching much importance to their work. ' Peclet, the first in this field, contented himself with reversing a flask filled with water in the gaseous current. Ebelmen 's experiments were as imperfectly conducted, though this remaik does not apply to his researches upon blast-furnace gases, which are much more uniform in composition. No more reliable are the experiments of Sauvages, whose samples were taken during some minutes from the grate of a locomotive in motion; nor those of Comines de Marsilly, whose sampling did not extend beyond a few seconds ; nor those of M. Debette, quoted by M. Combes in his report on the means of consuming or prevent- ing smoke. It is of vital importance that the sample operated upon should be thoroughly representative of the gases under investigation, and to this end the fire should be in operation at least a day before the conditions may be considered normal. It is also necessary that a large number of samples should be taken, or else (which is preferable) that the drawing should be a continuous one," 7l8 SCHEUEER-KESTNEE'a EXPERIMENTS. In Schearer-Kestner's investigations, a point in the chimney flue was chosen for the taking of samples in order to obtain the gases as well mixed as possible, and because Cailletet had shown that the gases in the imme- diate neighbourhood of the fire exist in a state of dissociation. The method of sampling adopted was as follows : — "A column of lo metres of water, 3 centimetres in diameter, was employed to aspirate a considerable quan- tity of gas from the flue, and from this current on its way from the flue to the aspirator, a second sample was drawn into a glass gas-holder con- taining several litres of mercury." The drawing of samples extended over the whole period of an investigation. The fact having been established by earlier research that combustible gases, such as carbonic oxide, hydrocarbons, and hydrogen, always exist in the products of combustion even in presence of an excess of oxygen, Scheurer-Kestner showed that the amount of the excess of oxygen governs the proportion of combustible gases present. Some of the old analyses are considered by him to be worthless, because they sometimes show an excess of both oxygen and combustible gases present together, and sometimes a deficiency of both. Scheurer-Kestner made an exhaustive series of experiments to determine the most advantageous proportions in which air should be admitted. " When Eonchamp coal was supplied with 8 to 9 cubic metres of air per kilo., the combustible gases escaping unconsumed amounted to from 6 to 18 per cent, of the carbon in the coal. With 10 to 12 cubic metres, the loss fell to 4 to 6 per cent.; and with 15 cubic metres it was only i to i| per cent. The net result of these experiments led to the conclusion that an excess of air should be employed amounting to about 50 per cent, of the quantity theoretically required. To ascertain the loss occasioned by smoke, a measured quantity of the gas was aspirated through a glass tube lightly packed with asbestos for a length of 25 to 30 millimetres. This filtering apparatus was placed side by side with the tube through which was passed the sample for analysis. The black discoloration, which did not penetrate more than 5 to 6 mm. into the asbestos, consisted of carbon and hydrocarbons, which latter imparted to it a tarry consistency. The quantity was determined by com- bustion and subsequent weighing of the carbonic acid formed." Even when a thick black smoke was purposely produced by limiting the air supply, the loss of heating effect due to smoke formation only amounted to i J per cent., and an increase of air reduced this to ^ per cent. " Smoke is formed in two ways. Berthelot has shown that certain hydro- carbons when heated to suitable temperatures are decomposed with forma- tion of a new hydrocarbon and deposition of solid carbon. This takes place on the grate where combustion is going on." The second way is by the dissociation of hydrocarbon gases due to cooling. This is shown by an ex- periment of Deville's. A curved copper tube is introduced into the gaseous current just behind the fire-bridge, both ends of the tube projecting out- wards. When this tube is kept empty it soon attains the temperature of the gases at that point, and when withdrawn shows a coating of cupric and cuprous oxides according as the gases have been more or less oxidizing or reducing. When, however, water is allowed to circulate through the tube so quickly as to keep it cool, then it is thickly coated with smoke-black produced from the dissociation of the gases. " The volume of air passing through the grate was calculated from the composition of the products of combustion, the following formula being used : — r p V" o(rl- — 5 — , INVESTIGATION OF CALOEIFIC VALUES. 719 where V represents the volume of air employed per kilo, of coal burned, 0, 0, H, S = respectively the carbon, oxygen, hydrogen, and sulphur in grammes per kilo, of coal burnt. 0.000536, V, V", V" represent respectively the carbon, carbonic acid, carbonic oxide, and oxygen contained per litre of the products of combustion, 8 = the equivalent of oxygen, 0.001437 =the weight of a cubic centimetre of oxygen, 4.761= the proportion by volume existing between air and the amount of oxygen it contains. Only the pure coal actually burned was taken into consideration, the neces- sary deductions being made for ashes, &c., passing through the fire-bars." In conjunction with M. Meunier-DoUfus, researches were carried out on a variety of specimens of coal in order to establish some relation between the nature of the coal and the gaseous products of combustion. The results did not differ much' from those obtained with Rouchamp coal. Investiga- tions were »also made to determine 'the calorific -value of coal, as Dulong's estimate of the average heat of combustion of coal at 7,600 calories was not considered wholly satisfactory. In the case of the determinations made by Scheurer-Kestner and Meunier-Dollfus, " the samples operated upon were obtained by repeated subdivisiojis of the bulks of coal actually u.sed at the boiler fire, and as finally obtained consisted of about 10 grammes each, in the state of fine powder. The representative character of these samples was established by the close agreement between the percentages of ash yielded by them and the weights of ash actually obtained from the boiler ash-pits." The calorimeter of Favre and Silbermann was used in these investigations, but with some modifications rendered necessary by the fineness of the samples and their very small bulk — not more than 5 or 6 decigrams having been experimented on at one time. In consequence of the very small I'ise of temperature produced in the calorimeter bath by the combustion of such small quantities, a special ther- mometer was made by M. Baudin for these experiments. " It contained 63 grammes of mercury ; each degree occupied a length of 36 millimetres on the scale, and was divided into fifty parts, but could be read to a five-hundredth. This instrument was also on Walferdin's metastatic principle, serving for all ranges of temperature, though its stem only com- prised 10° C." Scheurer-Kestner also found that, " as was stated by Mulder, K^ soda-lime was very much superior to pot ash as an absorbent for the gases produced by combustion." " From these experiments it was seen that the heats of combustion of different coals varied considerably, sometimes exceeding the values found by calculation, and sometimes (but more ra.rely) falling short of them. Gene- rally speaking, however, bituminous coals gave higher results and a larger volume of gaseous products of combustion than non-bituminous. The bitu- minous coal of Creusot gave 9,620 calories; the non-bituminous coal from Louisenthal in the Saarbriick district gave only 8,215. With the excep- tion of a Russian coal, which fell even below that of Louisenthal, these were the two extremes, the yield in most cases lying between 8,500 and 8,700 calories. It was found to be impossible to determine the calorific power of any coal with certainty save by actual experiment, as it almost always ex- ceeds that obtained by following Dulong's law, and often exceeds the addi- tion of the calorific powers of the total carbon and hydrogen present." The theory of M. Cornut, engineer of the Soci^te des Appareils-i-vapeur of Lille (referred to p. 709, ante), was applied to Scheurer-Kestner's results, and gave indications of its being " a means of arriving at the calorific power by calculation much more approximately than is possible by the use of 720 RESULTS WITH VARIOUS COALS. Dulong's law. If the heats of combustion of the two kinds of carbon and of the hydrogen be added together and the oxygen disregarded, the error rarely exceeds 5 per cent. In proof of this may be cited the fact that the heats of combustion of twenty coals from the North of France were deter- mined by actual experiment, and compared with the figures obtained by using M. Oornut's formula. In four cases the agreement was perfect, in seven there was a discrepancy of i to 2 per cent., and in six a discrepancy of 3 to 6 per cent., whilst in three the difference rose to 8 to 11 percent." A table giving all the results of these investigations from 1868 to 1874 is published in the BvMetin de la Societe Industridle de Mulhouse of June 1875, and the following abstract is due to D. K. Clark.* He says the authors state that, since the commencement of their labours, Messrs. Jamin and Amaury had demonstrated that the specific heat of water varies sensibly between the temperatures at which their trials were made ; and that the employment of the formula of these experimenters would augment by about 2 per cent, the tabulated quantities of the heats of combustion. All the numbers in the table have reference to the substance dry and pure — that is, to the combustible dried at 212° F. and free from ash. ANALYSES OF FRENCH AND OTHEE COALS AND LIGNITES, AND THE OBSEEVED HEATS OF COMBUSTION. Elements. Heat of Combustion Name of Combustible. Carbon. Hydro- Oxygen and of I lb. of Pure Fuel. gen. Nitrogen. English Units. Coal. per cent. per cent. per cent. Ronohamp, 3 samples 88. S9 4.69 6.72 16,416 Saarbrucken, 7 „ . . 81.10 4-75 14.15 >S>320 Creusot, 4 „ 90.60 4.10 5-30 16,994 Blanzy, Mcintoeaii 78.58 5-23 16.19 14,985 ,, anthiacitio 87.02 4.72 8.26 16,400 Anzin 84.45 4.21 11.32 16,663 Devain . . , . 83-94 4-43 11.63 16,290 English, Bwlf 91.08 3-83 5.09 15,804 ,, Powell-Duffryn 92.49 4 04 3-47 16, loS Russian, Groucheffski, anthraoitic 96.66 I-3S 1.99 14,866 ,, Miouclii, bituminous 91-45 4.50 405 15,651 ,, Golouboffski, flaming 82.67 5-07 12.26 14.438 Lignite. Rucber bleu 72.98 4.04 22.98 , 11,670 Manosque, bituminous 70.57 5-44 2399 13.253 " . <^r^ .■ 66.31 4-85 28.84 12,584 Bohemian, bituminous . 76.58 8.27 15-15 14.263 Russian, Toula 73-72 6.09 20.19 13.837 Lignite passing to fossil wood 66.51 4.72 28.77 11.444 Fossil wood passing to ligniie . • ' 67.60 4-55 27.85 11,360 Scheurer-Kestner repeated the experiments of Burnat and Dubied on the large scale, but estimated the volume of air used in combustion from the composition of the escaping gases, instead of by means of anemometer readings of the velocity of the inflow of air caused by draught. The boiler used by him was of " the kind common in Alsace, three- tubed, externally fired, and provided with a feed-water heater." This kind of, boiler is also called the "French" and the "elephant" boiler. In spite of precautions against the unobserved escape of heat, the experiments made in 1868 showed a deficit ranging from 21 to 27 per " " Min. Proc. Inst. O.E ," vol. .xliii. p. 396. DISTRIBUTION OF HEAT IN KESTNER'S TRIALS. 721 cent. In the case of Ronchamp coal the calories were distributed as follows : — As steam In chimney gases . As combustible gases escaping As smoke .... As water vapour in the smoke Not traced Per cent. 63.6 S-' 4-9 0.0 30 2-,.0 1 00.0 " Since that time, the feed-water heater has been changed for another of improved construction. The old one consisted of six cylinders placed two by two in a brickwork setting, and the feed water, traversing these, acquired a temperature corresponding to 8 per cent, of the total calories generated. With the new heater, which was on the tubular systen, the efficiency rose to 12 per cent. " An experiment made three years ago on a coal from the Ruhr gave the following results : — - ^^ Calories converted into steam . 67.3 „ traced in products of combustion 11. 6 78.9 "In a recent trial of an English coal of exceptional quality, almost smoke- less, and giving only traces of combustible gases, steam was raised equal to 74.5 per cent, of the total calories generated, and the deficit was reduced to 1 7 per cent. To get some idea of the direction of this loss it was suggested by an English engineer, Mr. Donkin, that the boiler should be put and kept under pressure for a given time, account being taken of the quantity of fuel required to maintain the status qu6, all outlets being closed. This experiment was carried out over several days and nights, and led to the conclusion that the loss by radiation from the boiler alone was about 4.6 per cent. Of the remaining 12 per cent, it is believed that almost the whole may be accounted for by external radiation. The return of steam was found to vary by from 8 to 10 per cent, according as the experiment was carried out in summer or winter. This fact was established by repeated experiments with different kinds of coal. Now, if the difference of tempera- ture between summer and winter can cause this variation (equal to about 7 per cent, of the total calories), it may fairly be inferred that, if we could estimate the loss resulting from the constant contact of the brickwork with the surrounding air, we should not fall far short of the total number of calories to be accounted for." The Industrial Society of Mulhouse* resolved in 1874 to make compara- tive trials with a Lancashire boiler, a French or elephant boiler, and a Fairbairn boUer. These trials were carefuUy carried out, and, although primarily of value in connection with questions of boiler design, give some information as to the evaporative effect of certain French and German coals when used on the large scale. The dimensions and general proportions of the boilers are given in the Society's Journal and by Mr. D. K. Clark.f The products of combustion in the Lancashire boiler passed from the inside flues on each side to the front and thence under the boiler to the chimney. In the Fairbairn boiler, they passed from the flues by the sides of the lower cylinders, and returned by the sides of the upper cylinder towards the chimney. In the French boiler, the current was not divided, but after heating the * Bulletin g CO . « VO ■* in »^ o\ •* r^ 00 •* Ov ■* Wa const] from perH .= VO rC. ■^ d m d yo t^ rn en 00 d 00 dv d 00 00 00 tC t^ K 00 00 r^ tN. t-* t^ 00 r^ K. Coal sq. ft. Grate ■ Hour. i vS 00 o a *£ O d 8 d ^ 8 en R d >§ R d 8v 8 I=E- w w M N « N M « « « N N "S is 1-1 ro 00 u^ Tf in 00 ^ ,.4 Th b4 VO ■* a r^ o i N en o N VO JO VO O m M t^ 1^ 00 as u in in in ■. N OS 00 •I On tN* N n ■* 1 lA o i>l N M « vd vd N e^ N ^ ^ 2" 4 l^J d in T "7 q "7 m ^ q 1 1 1 1 t CO « m M 1 1 1 ji" • o ^ +a ^ o a IP N cJ "'"' .s 11 ED cc 2S » (S ■g 03 03 .s 0) c; P4 ^ :; • 9 - 3 ^ - ■i :; ■s +5 C 'i a '^ N a "5 V •c r= Q '5 4i ■s fS *3 ^' H n r^ 'c -3 o ■ ^ -. •; >, .^ >% .ij r. >, . - t>^ o c ^ ce rt 02 5^ ^ c3 IB a P » □0 CS fe 'm » 68 fe SS fc eS s: r p o ^ t> S o o a c a a B as « 3 e« c€ e« ce ■^ o! ce S r. t- tt J o hJ O 7 O >-; o < BOILERS TTSma HINDLEY YAED COAL. 725 q q d 6 d d d d d 6 d d d d 6 d d d d d J4 M « c s £ E E E - - s E E E - * E s E rO 6^ q q q ■* M f^ in VO r-. q m ■sf 6 6 ° d d d d d *^ d d d d d d d S ? _ _ _ ^ tf 10 Oi « ro no CO CO 00 « VO lO VO r^ On H. vq M N d d d •* vd M w M M ro ix vd d d M M CO N ■♦.» ^ fei3 >» h 0:1 — - - > ^ N iri N « N « ~ 00 t^ NO ~ 00 10 NO NO t*. c^ "^ '^ VO 0^ N N « 00 ov »o r^ 1" 10 tN, VO 00 LTJ "^ 00 NO 6 d Ov - ~ ^ d d d It - - ^ ^ ^ ^ " = i-i o\ 00 t-t 00 ov N On 00 NO in On ro e» « r^ •* r^ ■* « << ■^ In. HH Ov tn NO M CO ^ N M N to ro ro CO CO CO CO M C4 fO CO CO fO fO CO CO r^ 10 « N •* M Ov ■* *^ 8 CO N uO ■^ ro NO 00 « 10 VO M »^ 00 >-t m « NN *^ On >o t->. NO r^ CO « M * lA ro tC. CO ci M dv M r^ CO r^ CO TJ- »>1 v^ NO On On 00 00 ^s. *^ t^ 00 00 t^ 00 00 o» 00 r^ On 00 00 00 N t^ ir^ m OV ov u-l I^ ■* M N Ov ■8 N 10 ON 10 « ON VO e. VO CO r^ CO ON ■* t^ On N ■* CO ON t^ 06 1.^ N h^ d cfi d d NO 00 CO d « d-. ON d c* w M f) M « N C4 M N « On r^ fO 1^ 1^ ^^ ■* ov NO NO 00 VO N NO li-> t^ 1 -"d- a^ m CO r-» VO VO i^ 00 !>. f2 •0- On NO u^ r^ in Ti- lA ■i- •& 4 4 10 ■4 \r, 1^ ■* fn iTi 4 4 4 ^s. Q Th ■* r^ tv. r^ CO a Ov li-i 00 rn ■<* w '^ Sv Ov CO Ov ^ c» m CO t^ Th 00 NO ='■■ ^1 ■sg» s - 1st Series. — Coalb in Stoee, sq. ft. cwts. lbs. cub. ft. GUb. It. lbs. recently delivered. With common doors — Welsh — Waynes Merthyr, Eesolven, Merthyr Dare, Gellia Cadoxtou . Hartley Main, Newcastle 14.0 1-93 15-44 32.4 2.31 10.42 14.0 2.32 18.56 34-5 2.46 9.22 4 Welsh, 4 Hartley 14.0 1.92 15.40 30-4 2.17 9.81 2 „ I „ 14.0 1.76 14.08 28.7 2.05 10.12 I „ 2 I. 14.0 1.96 15-70 307 2.20 9-72 With perforated door — Hartley Main . . . . 14.0 2.06 16.50 30.2 2.16 9.10 2nd iSeries. — Feesh Coals, specially ordered for trial. With common doors — Welsh — Powell's Duffryn, Nixon's navi- gation, Davis's Merthyr . 14.0 2.09 16.68 37-1 2.65 11.05 Newcastle — Davidson's Hartley, Has- tings' Hartley 14.0 2.29 18.29 345 2.46 9-39 4 Welsh, 4 Hartleys . 14.0 2.03 16.24 34-4 2.46 10.50 2 ,„ I „ 14.0 2.43 16.36 35-0 2.50 10.61 I „ 2 „ ... 14.0 2.06 16.44 33-5 2.39 9-43 Welsh .... 14.0 2.19 17.48 39-3 2.80 11.16 yd Series. With peiforated doors — Welsh coal ... 14.0 1.87 14-95 32.7 2.34 10.86 Hartleys 14.0 2.13 17.04 32-8 2.34 9.61 4 Welsh, 4 Hartleys . 14.0 2.18 17.44 37-1 2.65 10.54 2 „ I „ ... 14.0 2.08 16.64 35-7 2-55 10.64 I „ . 2 14.0 2.18 17.42 36.5 2.61 10.39 Davidson's Hartley I/l 2.86 22.88 42.9 3-06 931 4 Hart^ey, 4 Welsh 14.0 2.30 18.40 31.0 2.22 10.80 4«7j Series. — With Smaller Grate Are,\. AVith common doors — AVelsh coal 10.5 2.: I 22.46 38.3 3-65 11.31 4 Welsh small, 4 Davidson's Hartley 10. 5 2.02 21.60 36,0 3-43 11.06 1 „ beans, 4 Hastings' „ 10.5 2.14 22.85 36.7 3-50 10.65 $th Series. With perforated doors — Hartleys . .... 10.5 2.29 2440 42.0 4.00 11.42 i Welsh, 4 Davidson's Hartley . 10. 5 2.10 22.34 39-3 3-74 11.65 EESULTS OF KOYAL AGRICULTURAL SOCIETY'S TRIALS. 729 RESULTS COMPILED FBOM TABLES OF TRIALS OP PORTABLE ENGINES, ROYAL AGRICULTURAL SOCIETY, CARDIFF, 1872. Boilers all Locomotive Tjpe, except M. whicli was a Vertical Boiler with circiUating Water Tubes. Fuel Llangeiinech (W el.^h) Coal. Theoretical Evaporative Power trom 60" = 13.2 lbs. L. -=1 It. ill a eS < 1 1 pi II 11 eg II 12 is 1=3 p"S es Ill '■S'S 1.1 ■s III Itl p. i ■sS,w ►a CD M* ri u III |1| lis. fiq.ft. bq. ft. cu.ft. lbs. cu. it. lbs. cu. ft JtlB. CM,.(t, 1J!)B. ' lb.. lb.. A 3.00 283-5 94 6.5 417 .022 1-4 .142 8.86 2.17 139 15.70 .16 .671 B 3 -20 Z20.0 70 6., 419 .030 1.9 .104 10.24 2.00 131 12.80 .18 360° to 418° .776 C 3'ZO 220.0 70 6.3 409 .029 1.8 .164 10.23 1.99 129 12.50 .18 390° to 415° •775 D 5.10 170.6 33 4-7 296 0.27 1-7 .063 3-93 0.92 58 14.80 .43 548° .300 G 2.00 193.0 q6 — — — — — 19.15 .50 P I59-I 4.6 287 C.17 i.i • 151 9-43 1.4b 90 9- S3 .19 ■^^5° .714 G . 4.70 158.0 34 7-9 493 0.50 31 .127 8.08 1.61 105 13.00 •.38 about 600° .612 H 2.37 211.0 8q 7.0 438 0.32 2.0 ■145 9.08 2-53 185 20.40 .23 425° to 435° .688 I 1.60 151.6 .94 ■ — — — — — — 35.10 ■ 37 J 3*50 187.8 54 10.0 622 0.52 3-3 ■ 137 8.60 2.86 177 20.70 .38 500° .651 K 129.8 26 8.3 522 0.51 3-2 .124 7-77 1.66 104 13.60 ■52 over 600° .58b L 2.00 204.S 102 8.0 499 .038 2-4 .128 8.03 4.00 249 31.10 .30 ( at end of 1 1 run 360' ) .608 1 ^ 3.75 168.4 45 5-9 370 .044 2.8 •152 9-54 1.71 100 10.30 ■23 320° to 380° .723 A very interesting record of evaporative results was given by Sir Frederick Bramwell,* as obtained by himself and Dr. Russell in 1873, with a vertical boiler with internal circulating pipes. The fuel used in this case was ordi- nary gas coke, which had absorbed 10 per cent, of moisture from exposure to the air, although it had been kept in a covered shed. The plan of trial pursued was practically that adopted by the Eoyal Agri- cultural Society. Steam was got up and the boiler was worked for a short time with steam at 53 lbs., the water-level being normal. The hot fuel was then drawn out and weighed, and put back again with 10 lbs. of wood. The coke had been previously weighed out in parcels of 14 lbs. each, and the time of finishing each of these and each measure of water was duly noted. At the end of the trial, steam, water, and fire having been brought into the original condition, the fuel in the furnace was weighed. An ane- mometer was placed in the opening to the ash-pit in diiferent parts to re- gister the entering air. A thermometer was placed in the chimney and samples of the waste gases were analysed. The feed-water was weighed, and precautions were taken to test the steam for priming water. An ingenious method was also adopted for estimating the loss by radiation and convection from the boiler surfaces, and the results were arranged in the form of the following balance-sheet, to show at a glance the various elements of the experiment. » "Min. Proo. Inst. C.E.,' vol. lii. p. 154. 730 BRAMWELL AND RUSSELL'S BALANCE-SHEET. BALANCE-SHEET, SHOWING EBSULTS OF TRIAL. Duration of Experiment, 4 hours 12 minutes. Dr. Cr. lbs. lbs. lbs. lbs. To gas coke . . 228.25 By water in coke . 24.08 „ wood . 10.00 „ ash ... 10.33 / „ hydrogen, oxygen, nitrogen and -sul- phur . . •3.42 37-oj / „ water in wood 2.00 / „ ash . . 0.20 / „ hydrogen 0.49 y/ „ oxygen . 3,27 / S-96 / Balance, being useful combnstiblt i 194-46 238.25 238.25 Heat nnits. Heat unite. To balance of useful combustible B.y 3,330 lbs. of air (being I7| lbs. brought down 194.46 x 14,000 of air to i of carbon) raised (units of heat per lb. coal) . 2,722,440 from 60° to 700° (the tempe- / rature of the outgoing gases) 3, 330 lbs. X 640° X .2379 . 506,880 ■/ ,, 26.08 lbs. of water in fuel turned into steam and raised /' in temperature . . 36.251 / „ radiation and conduction in the / 4 hours 12 minutes . . . 70,430 / „ 1,620 lbs. of water raised from / 60° and turned into steam at / 53 lbs. pressure 1620 x 1.145 i 854,900 / 2 468,461 Unaccounted for . . 2 253.979 2,722,440 722,440 The/ following particulars accompanied the balance-sheet : I O P.M. 1 50 ., 2 55 » 40,, 4 24 .. Temperature in Flue during Experiment. 670° F. 610 750 . 770 experiment stopped The temperature of the air was 70°, the reading of the barometer 30.07 inches. ANDERSON'S ANALYSIS OP BKA.MWELL's RESULTS 731 ANALYSIS OF GAS IN FLUE. Before Firing. After Firing. Between firing. Average. Carbonic acid Oxygen . Nitrogen Combustible gas Total per cent. 9.42 II. 16 79.42 per cent. 12.91 7.16 79 93 per cent. 10.19 10.16 79.65 trace per cent. 10.84 9-49 79.67 100.00 100.00 100.00 100.00 Mr. W. Anderson* submitted these results to examination in accordance with Garnet's theory, and succeeded in accounting for a considerable portion of Sir Frederick Bramwell's deficit of 253,979 units of heat "unaccounted for." Mr. Anderson added the " work " required to displace the atmo- sphere by the waste gases, that is, to produce chimney draught, and by doing so, he remarked that " the unaccounted-for heat falls to less than 4 per cent, of the total heat of combustion. These results show how extremely accurate the observations must have been, and that the loss mainly arises from con- vection and radiation from the boiler." The result is superior to those announced by Scheurer-Kestner, but probably the use of the anemometer and the method of analysing the waste gases were possible sources of unob- served loss. The following is Mr. Anderson's analysis : — " Potential energy of the fuel with respect to absolute zero — Units. 238.25 lbs. X 530° abs. X 0.238 = 30,053 194.46 ,, X 17I X 530° X 6.238 the weight and heat ofair ....... . = 420,060 194.46 X 14,544 unite heat of combnstion of carbon = 2,828,200 Total energy 3,278,31 J Heat absorbed in evaporating 26.08 lbs. of water in fuel . . - 29,888 Available energy 3,248,425 " Temperature of furnace — " The whole of the fuel was heated up, but the heat absorbed in the evaporation of the water lowered the temperature of the furnace, and must be deducted from the heat of combustion. Units. 2,828,200 29,888 Heat of combustion .... „ evaporation of 26.08 lbs. water Available heat of combustion . 2,798,312 Dividing by 238.25 Ibe. gives the heat per i lb. of fuel used . ■ = And temperature 1 "'745 + c^o" = of furnace J l8.I2Slb8. x 0.238 "^ ^^ Temperature of chimney 700° + 460° . = 3,253° - 1,160° Maximum duty o = 0.643 Work of displacing atmosphere by smoke at 700° — Volume of gases at 70° 700° Increase of volume . 271. 11,745 3,253° 1,160° Cubic Feet. = 228.3 = 499-8 " " On the Generation of Steam," &e. ; Inst. O.E. Lectures, 1883-84. 732 ANDERSON'S ANALYSIS OF BEAMWELL'S EESULTS. Units, Work done = »94-46 lbs- x Z7I-5 cub, ft. x 144 sq. in. x Ig Iba . ^ 147,720 ' 772 units Maximum amount of work to be expected = 3,248,425' x 0.643 = 2,101,700 Deduct work of displacing atmospbere . . . . . = 147,720 Available work . . 1,953,980 ■ Actual work done — Units. 1,620 lbs. of water raised from 60° and turned into steam at 53 lbs. ,._.... = 1,855,900 Loss by radiation and convection . 70,430 [04 lbs. asbes left, say at 500° ... . 1,129 Total work actually done . 1,927,459 Unaccounted for ... . 26,521 Calculated available work . . 1,953,980 " The work unaccounted for therefore amounts to only i J per cent, of the calculated available work." ANALYTICAL TABLES. FAT BITUMINOUS COALS OF ENGLAND AND SCOTLAND. Description and Locality of Coal Beds, By whom analysed and described. 1 i 1 CO. Analysis of 100 Parts of Coal. 1 i |1 Alt'reton, furnace coal .... Butterly „ Derbyshire Derbyshire, cannel coal, Alfrelon Wigan, cannel coal » n Lancashire, „ ... Woodhall, near Grlasgow, cannel coal . Liverpool coal D. Mushet i» »i Dr. Thomson Kerwan K. C. T. . Dunn Dr. Ure Johnson I -235 1.264 1.278 1.272 1-275 1.228 1.260 52.46 52.88 48.36 52.60 75.20 6173 56.40 S4.90 45.50 42.83 47.00 44.C0 21.68 41.00 40.48 2.04 4.29 4.64 3-4° 3.10 2.60 4.62 FAT BITUMINOUS ADHESIVE COAL, COKED PREVIOUSLY TO USING IN THE FURNACE. Newcastle-upon-Tyne, Birtley Works . Dufrenoy & Bertbier 1.270 60.50 35-50 4.00 Thomson — 65.90 32.60 1.50 Karsten . 1.256 67.65 31-50 0.85 N orthuinberlanil, Tyne Works Dufrenoy & Bertbier — 67.50 30.00 2.50 Staflbrdshire, Apdale Works )» :I . — 62.40 34.10 3-50 Redesale, Newcastle-on-Tyne Richardson — 49-95 51.00 3-05 Wylam — 48.49 37.60 13-91 Garesfield and Auckland — 72.71 25.90 '-39 Newcastle coal (mean) W. E. Johnson 1.257 57.00 37.60 5-40 BITUMINOUS COAL, USED CRUDE IN THE HOT-AIR FURNACE. Description and Locality of Coal Bed^. By whom analysed and described. Analysis of 100 Parts of Coal. ^1 Bitumen, Volatile Matter, and Water. 1" Staffordshire, Tipton, Wednesbury coal woiks Derbyshire, Butterly, cheiTy coal Derbyshire, Codnor Park, soft coal Soft or mixed English Bertbier ,, ... D. Mushet .' 67.50 57.00 51-50 53-00 30.00 40.00 45-50 2.50 3.00 3-00 734 ANALYSIS OF COALS. BITUMINOUS AND SEMI-BITUMINOUS COALS OF SOUTH WALES. SIDE OF THE COAL BASIN. ON THE EASTERN Analysis of icxj Parts Description and Locality of Coal Beds. 1 of Coal by Mushet. The Coal described, and its Uses. 1 3 1 < Al,„™„„l,a., (Meadow vein . Abersychan |o,j^„^, _ ft. in. 8 6 65.98 29.40 4.62 thin laminae, furnaces. 2 6 71.10 27.40 2.50 laminae „ Three-quarter . S 6 71.88 25.50 2.62 ff It fJolynos Kock vein . 7 69.60 27.40 3.00 thin laminae, run out fires. Ironworks Meadow vein 7 o 68.00 27.50 4-53 dense, furnaces. Old coa' . 2 4 73-40 20.60 6.00 laminae . „ Eed vein . Big vein . Droydeg or rock vein . Three-quarter . ^ Meadow vein . 4 f9-4S 26.30 4-25 it tt Verteg Iron- 4 o 66.05 30.70 3-25 irregularly laminated,fumaces. works. Fur- 4 64.45 32.30 325 oblimg, forge and mill. nace coal S 6 67.90 29.60 2.50 rather friable, furnace. 7 o 69.25 30.50 9.25 thin laminae „ Three-quarter . S 6 65.63 31-25 3-12 tt tt Blaenavon Droydeg or rock vein . S 6 65- ss 28.95 5-50 cubical, refineries. Ironworks Meadow vein 2 lO 72.00 26.00 2.00 „ furnace. Old coal . 6 o 75-21 22.29 2.50 laminated „ Red vein . 3 o 76.58 20.80 .1.62 „ forge and mill. Big vein . S o 73-42 24.58 2.00 thin layers „ Clydacii or Three-quarter . 2 9 72.70 25-30 2.00 broad „ Llanelly Droydeg or rock vein . Tach coal . 7 o 72.13 21.87 6.00 cubical „ Ironworks 3 o 70.05 25-57 438 cones, household. Yard vein . 2 9 78.68 19-32 2.00 hard, furnaces. Old coal . S 6 77-55 18.9s 350 alternating laminae, furnaces. Elled coal . 3 6 81.87 17-13 1.00 lamellar „ Nant-y-glo Three-quarter . 82.65 15.10 2.25 coking, for the refineries. Ironworks Droydeg vein — 77-14 1786 500 twisted, forges and mills. Old coal . 5 6 78-75 18.75 2.50 imperfect, furnaces. Ellceal . 82.04 16.71 1.25 sectional „ Three-quarter . — 8350 12.00 4-30 with numerous partings. Big vein . 8 o 81.52 15.10 338 rhomboidal, furnace. Sirhowey Ironworkfl Mudelog vein or droy- deg . . . — 80.50 11.87 7-63 partially granulated. J-lUUWUl&D Yard coal . — 82.24 15.88 1.88 twisted, with clod. Engine coal 4 o 82.46 15.41 2.13 irregularly granular, furnaces. Three-quarter engine . , Old cod . 75-78 13.22 11.00 bard. 4 78.50 13.00 8.50 conchoidal partin<;s. ' Yard coal . 3 2 81.04 15-83 3-13 friable, forges and mills. Three-quarter . 3 80.25 17.00 2.75 cubical, blast furnaces. Ebbw Vale Big vein . 4 8 81-37 17.00 1.63 „ „ and forges. Ironworks Bydelog or droydeg . Ell coat . 2 lO 72.88 16.87 10.25 coarse „ „ .&1 \/JU T^ \JA ^O 3 2 82.32 16.30 1.38 granular „ „ Old coal, top . 1 , , bottom J 5 6| 79.28 18.22 2.50 cubical, force and mill. 81.77 15-73 2.50 less_ granular, blast furnace. Beaufort Old coal . 4 6 76.82 20.80 2.38 cubical, liirnace and refinery. Punt-y-mister Forge coal . 75.06 22.22 2.72 „ „ forge. Blaina Jj^jg^^'" • • " 1 Three-quarter . S~6 72.14 25-86 2.00 granular S 6 77-38 21.12 1.50 cubical „ „ Big vein, top „ lower part . Tredegar Eed vein, upper part . 3 o 80.45 16-55 3.00 compact, blast furnace. 3 o 81.56 14.94 350 very compact „ I o 79-44 14.06 6.50 laminated. Ironworks i ,, under part . 3 o 80.26 18.49 I-2S reedy laminae, blast furnace. Bydelog (droydeg) 3 78.90 17.97 3-13 fine laminae, forge. Yard vein . - 82.26 15.36] 2.3s reedy laminee, blast furnace. ANALYSIS OP COALS. 735 BITUMINOUS AND SEJII-BITUMIKOUS 00AL8 OP SOUTH WALES — {continued). Analysis of loo Parts Description and Locality of Coal lieds. •g S ■s % 1 of Coal by Mushet. The Coal described, and its Uses. 1 a E S CO 1 < Penmark vein ft. in. 8o.li 14.06 S.8s reeiy, forges and mills. Tredegar Three-quarler . — 80.20 13.80 6.00 laminae with clod. Ironworks Engine coal, or old coal S 6 77. so 15.20 7. SO reedy. ( Big vein, upper part . 81.26 16.24 2.50 partially reedy, blast furnace. ,, lower part . — »2.,^-? I.-?. 17 4- SO strong , , Raslas vein 7 82.79 12.96 4.2s reedy " ,, Rhymney Ironworks Brasaey vein I 3 8s.-;8 I4-S7 2.25 twisted, workmen'ti fires. Red coal . 3 6 84.2s IZ.7.'; 3.00 granular, furnaces. Yard coal . 80.92 16.20 2.88 irregular „ Four-feet coal — 80. IS 15.10 4-75 irreg. laminae, forges and mills. Fire-clay coal I 80.60 17.40 2. CO reedy. ^ Black vein 2 6 82.51 14.99 350 „ forge. SEMI-BITUMINOUS 3R STEAM COALS DF SOUTH WALES. Red vein 4 83.04 14.58 2.38 thin laminae. Bute Iron- Big vein . 9 8353 13-74 2-73 ,, works Raslas vein 9 84.06 12.44 3-50 ,, Four-feet veiu . 4 78.30 1645 3-25 in compact, forges. Big vein, upper part 'S 80.88 15.62 3-50 reedy, blast furnaces. Middle part . II ' 85.00 n.87 3"3 thin layers, brittle. Bottom part . 82.81 13-44 3-75 irregular, shining. Raslas vein,iipper part 9 o| 84.08 13.02 2.90 imperfect, cleavage. Dowlais ; Lower part . 85.02 13-23 1-75 strong, laminae thin. Ironworks \ Upper four-feet . 4 85-75 12.75 1.50 prisms, furnace coal. Lower four-feet . 4 85-35 12.40 2.25 shining laminie. Cwmcenol . 2 9 88.63 9-74 1.63 in layers, furnace coal. Four-feet (brge 5 88.78 7-97 3-25 part reedy, forge coal. vLittle vein 3 86.90 11.72 1.38 thin laminae, forges. /Foes-y-frane 7 85.04 11.46 3-50 compact, blast furnaces. Raslas . 7 87.69 10.31 2.00 incompact „ *Pen-y- darren Iron- / works Three-feet coal . 3 85.07 12.18 2.75 broad „ Four-feet coal . Upper vein 4 3 6 88.50 86.08 10.00 10.42 1.50 3-50 hard ;, „ forges and mills. Roof-pin veiu . 2 83-30 11.20 5-50 „ mixed quality. Big vein . — 86.01 12.24 ••75 crystallized, with clod. \Bottom coal 4 87.20 11-30 1.50 compact, forges. /Upper or yard coal . 3 9 79.06 15-34 5.60 mixed „ Four-feet coal . 4 84.98 11.77 3-25 „ less shining. ♦Plymouth & Duffryn ( Ironworks Clynmil coal, top part 3 6 86.62 12.00 1.38 conical, best furnace coal. Bottom part . Raslas, top part . 4 6 4 6 85.48 82.05 12.39 13-95 2.13 4.00 granular, blast furnaces, bright Bottom part . 3 6 83.84 13-33 2.83 both reedy and granular. Upper Dingle coal 3 6 7700 ZO.00 3.00 broad, forges and mills. \Lower Dingle . 2 6 80.34 16.66 3.00 less bright and shining. ' Cyfarthfa big vein 9 90.28 7-97 I-7S slightly reedy. Cwm-dhu pit . 6 S8.78 9.22 2.00 regularly laminated. *Cyfarthfa& Cwm-mynedd S 6 88.87 9.00 2.13 slaty, forges and mills. Ynnis Vach. Cwm-y-glo . 4 89.29 6.58 4-13 incompact, blast furnaces. Merthyr Upper yard vein 3 86.80 11.20 2.00 regular ,, Ironworks Gelly-deg . . 3 91.86 6.14 2.00 specular, forges. Mountain vein . 3 6 90.02 8.48 1.50 crystallized, furnaces. . ,, ironstone . I 6 92.11 6.14 1-75 reedy, granular. On the northern side of the coal basin. 736 ANALYSIS OF COALS. SEMi-BiTCMiNoua OE STEAM COALS OP SOUTH WALES — {continued). scription and Locality or Coal Beds. AnalysiB of loo Parts of Coal by Mushet. The Coal described, and its Vaea, Aberdare Ironworks Hirwain Ironworks *Argoed in Cwm Buchan *Oakwood Glamorgnsh. second coal series *Cwm Buchan third coal series 'Pyle, lower series /rour-feet coal Baslas vein Two-feet coal Small vein Foes-y-frane Two-feet 9-inch coal Yard vein . Black mine coal . \ Upper vein Big vein . Four-ft. coal, or Glowynn Six-feet coal Pit vein Upper vein Lt)wer vein Wern Dhu Wern Pistill Rider vein . Tor Mynydd Four-feet, upper vein „ lower part Nine-feet coal Yard coal . J Vein fawr, I I „ 2 87.00 88.89 88.12 80.42 84.67 88.51 82.99 91.18 82.12 88.94 90.26 82.96 87.15 76.54 74-30 78.02 80.06 80.67 81.18 91.67 88.65 8374 78.90 72.82 72.58 11.50 9.11 10.00 10.83 8-33 9-99 14.26 6.82 12.13 7.18 7.86 8.04 8.85 22.50 23.40 20.18 17.46 18.52 18.00 7.70 10.00 15.20 20.00 24.68 24.42 1.50 2.00 1.88 8-75 7.00 1.50 2.75 2.00 5 75 3-.8S 1.88 2.06 4.00 0.96 2.30 1. 80 2.48 0.81 0.82 0.63 "■35 1.06 1. 10 2.50 3.00 compact, blast furnaces. „ forges, mixed reedy and granular, compact, refineries. „ furnaces, bi-igiit reedy coal, reedy, furnaces, bright reeded coal, granular, with clod, crystallized, forges, slightly reedy, furnaces, regular reeded, forges, reedy and granular, friable, weak, harder, more compact, used for smelting iron, hard, compact, second coal series. strong, heavy coal. reedy, furnaces. large and lumpy. clean and bright. very bright reedy coal. cannel and bituminous mixed. BITUMINOUS AND SBMI-BITUMINOUS OR STEAM COALS OF SOUTH WALES, ON THE SOUTH-EASTERN SIDE OF THE COAL BASIN. Mynyddy- swyn vein, sa.1e cnaln fnr Cyfarthfa furnace 88.07 8.50 3-43 irregular crystallized. Powell's . 4 66.58 27.92 5- 50 cubical, compact, reedy. Morrison's . 4 68.58 36.92 4-50 )» >» II household * Penner vein 4 60.25 3300 6-75 slightly granular, reedy. 1 Jt \J U V UWX ^.4 Cwm Dows (Morrison) 3 4 68.86 27.14 4.00 purposes, Upper or red Prothero's . 4 6495 33-30 1-75 „ compact. Rosser Williams 4 68.50 30.00 1.50 no sulphur, clean. asu coais .Crossfield's 6934 24.16 6.50 cubical, compact. Beddws vein, Cwm Tillery 2 4 64.45 24.80 10.75 shining bright. Ijower Tpd * Phelps's . 2 4 68.00 30.00 2.00 compact, hard, strong. a ah poal Abercarne . 2 9 66.88 28.37 4-75 ,, cubical, reedy. ttoix KjUak Cwm Carne 2 9 62.63 31-10 6.25 II II i> Upper rock vein 3.6 66.11 31-14 2.75 for steam-packets. Lower rook vein 3 6 61.78 34.28 3-94 oblong noasses, reedy. f Risca veins- Big vein . 12 66.02 29.15 2.83 irregular, no sulphur. Red vein . — 61.25 33-80 4-95 pyrites, strong. Sun vein or Meadow vein 3 67.28 31-34 1,38 compact, reedy. Yard vein . 2 6303 32.60 4-37 with layers of splint. fCvvmBrane coals Rock vein . Red vein . 6 3 6 62.22 60.65 34-78 31-35 3.00 8.00 cubical, oblong, reedy. Meadow vein 5 8 66.34 2816 5-50 strong, bright, shining. Old coal . 3 68.30 27.70 4.00 cubical, tarnished. South side of the coal basiu. t The white ash or furnace coals. ANALYSES OF COALS. 737 STEAM COALS or SOUTH WALES— -(continued). Analysis of loc Parts Deaoription and Locality of Coal Beds. 3 s i £3 ofCoalbyMashet. The Coal described and its Uses. 1 k S3 i G Q S g < *Blaen-darej Rock vein . It. 10 in. 68.86 28.64 2.50 used for blast furnaces. furnace coals [ Meadow vein 6 67.84 29.16 3-00 n )i Big vein . * Pen Twyn Droydeg, or rock v> in furnace coals i Meadow vein 4 6 7188 25.50 2.62 laminae regular, reedy. 3 6 68.20 24.80 7.00 cubical. 7 63.65 32 60 3-75 cross or sectional, pure. ( Old coal . 2 6 68.50 27.50 4.00 incompact, friable. 'Abersychan [Red vein . 4 72-95 25-30 1-75 used raw in blast furnace's. Britisb Iron • Big vein . 7 6705 25.70 7.25 >j ), Company (Rock vein . 8 69.30 25.70 5-00 cubical, splint. /CribbwrVach . 4 6 72.36 26.14 1.50 bright, furnaces. Bedws vein 10 70.68 25.82 3-50 ,, in thin laminas. f Park, south Maesteg issa S 79.69 19.26 1.25 „ blast furnaces. veins of the Llangonydd 5 60.40 38.60 1.00 j> ») South Wales! „ ' No. 2 coal basin, ( „ 20-inch . 2 6 69.64 27.86 2.50 imperfectly rhomboidal. I 8 70.22 28.28 1.50 broad, reedy coal. between Pyle Hirwain common 4 6 69-34 29.16 1.50 smooth fracture. anu Llantris- ,, 2-yard coal . 4 73-75 22.50 3-75 slaty, partially reedy. sant Llanharry . 6 65-75 33-00 1.25 strong, reedy coal. CoUenna i-feet . 3 75.06 2344 I- SO broad, reedy structure. \ „ cannel coal 3 63.25 34.12 2.63 laminated, oolitic. ( Little vein . _ 70.66 27-34 2.00 workmen's fires. f Mellin Brassey vein 2 4 61.00 30.00 9.00 heavy, forges and mills. Criffin and Pentyrch liard vein . 4 71-25 23-75 5.00 crystallized, blast furnaces. Pentyrch, „ forked vein . 5 6 64.63 31-87 4.50 reedy, tin plate works. near Cardiff „ wing coal . I Pure anthracite . 5 95.69 2.81 1.50 „ furnace and forge. Verv dry, [po^i^ia ironworks . o7arbonin-Cyf-"^f^ " _ 79-5° 17-50 3.00 lamellar, does not cake. - 78.40 18.80 2.80 „ cakes. smies r^-y-'i-™"'' • ~ 76.80 20.00 3.20 j» )) ANTHEACITE OF SOUTH WALES, TOWARDS THE WESTEEN EXTENSION OF THE BASIN. Pwll-feron, in Neath valley,_ Neath Abbey furnaces /Pwll-feron vein, 1st bed Yniscyiiwn Ironworks 2nd , 3rd 4th 5th , 6th; Big vein Brass vein Cwm Phil vein . Swansea Swansea peacock coal 89.34 6.66 4.00 86.56 6.94 6.50 86.24 12.00 1.76 90.59 8.50 0.91 91.08 8.00 0.92 8I.C0 9.00 10.00 — 88.70 7.80 .S-50 — 88.70 7.80 ,3-50 — 89.60 6.66 3-74 — 89.00 7.50 3-50 mixed with coke, very liard and reedy, anthracite. more brilliant, more reedv. bright and shining, surface smooth. * The white ash or furnace coals. t Bituminous coals of South Wales, south side of the canal basin. By the term " reedy coal " is locally understood a coal in which the vegetable impressions are conspicuous and abundant in its substance, — "Clod coal," having a soft, laminated vegetable texture, ^"Splint coal," which does not lose its form in coking, angular, — "Semi -bituminous coal coke" where the angles of the cokes are rounded, and having considerable adhesion, — " Partially bitumi- nous," where the coked masses have rounded edges, and slightly adhere together, — "Bituminous cokes," those which dissolve and enter into fusion, forming a compact mass. 3 B 738 ANALYSES OF COALS. AMTHRACITE OF SOUTH WALES — (continued). Analysis of 100 Parts Description and Locality of Coal Beds. n 1 a of Coal by Mushet. The Coal described, and its Uses. g 1 S 3 r3 /"Big vein, I at bed ) ft. in. 91.42 7.08 1.50 blast furnaces. 2nd „ 6 o- 92.89 5.61 1.50 flat, boarded coal. „ yi „ j _ 91.99 6.51 1.50 reedy and granular. Ystal-y-fera Cefn vein, upper bed . — 91.26 7.24 1.50 pitchy, bright, shining. Ivon works, „ lower part . — 91.89 6.61 1.50 partially granular. Swansea Brass vein, upper part — 92.46 6.04 1,50 bright, laminaj irregular. valley „ lower „ — 91.52 6.98 1.50 irregular, reedy. Black vein — 93 '4 5-36 1.50 rough, crystallized. Little vein — 90.64 7.86 1.50 regular, but twisted. ^Pentyrch wynn . 5 95.69 2.81 1.50 reedy, forge and furnace. Cwm Neath ■ Three-feet vein . 3 94.10 4.90 0-93 ' Eighteen-feet vein 18 91-43 6.24 2.28 analysis by D. SchafhaeutJ. Nine-feet vein . 9 93 12 5.22 1-59 /Ginderlord furnace, or Lower High coal Dell' 3 62.00 36.00 2.00 stronglv reeded, bright. Park-end coal . 4 — — free from splint. Bituminous coals of the Goleford High Delf, top part . 4 6) 63.72 32-03 4-25 thin, bright laminae. Middle part . to 63.61 3489 1.50 reedy, bright, pyiitous. I.UIU0L Ul Dean, Gloucester- shire B ittcim „ . 6 60.96 37-29 1-75 smooth fracture. Churohway (top coal {bottom 5 6o-33 3567 4.00 irregular fracture. 64.13 34-74 1-23 smooth, straight, reedy. Rocky vein 2 61.73 36-14 2.13 strong, partially reedy. Starkey coal 2 6 61.53 36.72 1-75 partially reedy. Park-end, Little Ddlf I 8 58.15 36-35 5-50 compact, bright, reedy. \ „ Smith EnJ 2 63-36 34-89 1-75 heavy, compact, reedy. Tow coal, part of the *Corbvn's Hail ten-yard coal . — 51.90 40.60 7.50 strong, reedy coal. » j> — 56.00 4250 1.50 irregularly laminated. Heathing coal . Brooch coal — 54-17 43-33 2.50 strong, bright, reedy. — 50.49 47-76 1-75 bright, pitchy fracture. *South New mine top coal — 52.77 45.10 213 reedy, without splint. Stafford- Fire-clay coal . — 51.40 46-35 2.25 weak, friable, reedy. shire New mine bottom coal — 53-98 44.27 1-75 reedy, mixed with clod. (• Ten-yard coal . — 54.05 42.70 3-25 pitchy, bright coal. „ bott im part — ' 63-57 34-18 2.25 bright and thin splint. *Bentley Four-feet coal . 4 53-18 44.82 2.00 bright, shining, smooth. Estate, _ Three-feet coal . 3 54.82 43 '2 2.00 bright, pitchy, reedy. South Staf- Fire-clay coal . 5 54.84 42.91 2.25 strong, reedy, uniform. fordshire B ittom vein 7 62.87 32.00 5.12 hard, splint coal. Five-feet splint coal . 5 49-42 45-83 4-75 laminae minute. ■ Bottom coal 79-78 10 72 9.50 imperfectly crystallized. Bassey mine coal — 58.30 38.70 3.00 reedy, dull surfaced. Land end, Little mine coal 4 c )62.3c 35 20 2.50 compact. North Staf- Great row coal . 9 <■ 557-3S 39-74 2.88 smooth, thin laminae. fordshire Best furnace coal 10 65.2c 32-3° 2-SC bituminous-looking coal. Ashes coal — I61.32 37-18 1.50 bright, shining, cubical. • Bit> imlnous coals of Staff ordsh H-e. ANALYSES OF COALS. 739 BITUMINOUS COALS OP STAFFORDSHIRE, SHROPSHIRE, NORTH WALES, DERBYSHIRE, AND YORKSHIRE. Analysis of 100 Parts Description and Locality of Coal Beds. .a i o i ':= of Coal by Mushet. The Coal described, and its Uses. u J 5, Little Row cokI ft. in. 4 O 63.08 34-67 2.25 bright, with clod partings. £ g 1 Seven-feet coiil 7 o 67.90 3047 1.63 thin layers, furnace. 3 & ' Stony vein 8 O 65-17 33-33 1.50 compact. ~~ t3 i Banbury or Harecas — 63.84 35-16 1. 00 bituminous. l« Knowles's coal, Delph L^ne 10 o 59.64 37.86 2.50 bright, free burning. -S Peacock coal, Fenlon Park 9 o 60 42 37-08 2.50 cubical, furnaces. 2 aj [ Spendcroft vein i I Ten-feet coal . 4 o 58.67 39-58 1-75 broad, potteries. 7 o 58.89 39-" 2.00 nnifiirnily reedy, potteries. ^ 3 1 Great Row coal ^ Little Row coal 8 o 60.80 37-70 1-75 cubical, pottei'ies and halt works. 4 62.47 34-53 3.00 hard- „ „ Shropshire stone coal 58.17 39.20 263 bright, clod partings. Sulphur coal . — 55-72 42.03 2 25 broad,forinterior house purposes. I Clod coal . — 63-79 35-58 1,-63 reedy, furnaces. *« Kandle coal — 64.19 32-81 3.00 g- Flint coal — 60.63 36.87 2.50 hard, sale or smith's use. ,3 Top coal . . . . — 64.10 34-77 1-13 regular. CO Best fungous coal — 63-33 35-67 1. 00 minutely laminated, no pyrites. Uonble coal .... — 57-87 41.38 0.75 hard, blast furnace. _fg Three-yard coal, part not coked — 61.31 3580 2.89 fine „ s „ part coked 3 ° 62.70 35-70 1.60 strong „ 6 Two-yard coal coked 69.98 28.60 1.42 bright „ „J^ Brassey vein coked . 5 6 64.58 34.10 1.32 cubic ,, J g Crank coal 2 6 73-56 25.70 0-74 mixed, furnace and sale. Urowpall vein . 5 o 62.69 36.70 0.60 not firm, fne. Powell vein .... 5 ° 63.41 34.80 1-79 shining. «^ Five-yard vein, top part . „ middle . 61.89 36.20 1. 91 laminated, free. — 62.72 36.00 1.28 more compact, iron-making. „ bottom — 63.79 32-85 3-36 thin laminae, with clod. 9 Three-yard coal — 62.88 36-00 1. 12 compact, free. p Two-yard coal . — 60. 6 1 38-47 0.92 free, shining fracture. Bone coal — 55.20 40.00 4.80 hard, lead works. / Pankey Ironworks, stone vein . 2 O 61.95 35-67 2.38 broad, partly crystallized. Pant Ironworks,blast furnace coal I 7 67.25 31-25 1.50 graiiular, for blast furnace. Coed Talon .... 9 CI 58.50 40.00 1-50 surface „ ■ Sweeny colliery, Brassey vein . 3 o 49-94 34-56 15.50 alternate layers „ 03 Cefn colliery, near Ruabon "fl works . 7 o 57-49 36.56 6.25 ,1 •2 ,, Bi'assey coal . 3 ° 66.37 32-13 1.60 laminated. Black Park coal, 2-yard vein . 6 57-50 40.00 2.50 firm, with splint. o „ 1 4-yard vein . 4 6 59.88 38.12 2.00 strong, with clod. iz; Llwyn-y-onnion, J-yard coal . Chirke bank colliery, stranger.s 62.85 3440 2.75 smooth, reedy, hlast furnace. coal 5 6 57.00 40.00 3-00 hard. Delf colliery, yard vein, near V Ruabon .... — 64.89 34." 1. 00 compact. Kirby, upper hard or main coal 6 o 64.15 33-85 2.00 mixed, shining parting. S Dunsliill, near Swanwick . — 55-77 40-73 3-50 stiong, breaking oblong. ]3 Swanwick, main coal — 60.27 38-23 1.50 „ twisted laminsa. to ■ 5". Main, upper hard, Duckmanton — 64.47 32.03 3.50 „ blast furnaces. t Normanton Cora. Codnor Park . — 56.21' 41.66 2.13 free, forge and mills. P Main soft coal .... — 56.49 37-76 5 75 „ clod, spar. Alfreton works, lower hard coal | 4 o 62.60|3S.i5| 2.25 1 strong, blast furnaces. 3B 2 740 ANALYSES OF COALS. BITTIMIKOUS COALS OP STAFPOKDBHIRE, ETC.— {corvtinued). Analysis of loo Farts Description and Locality of Coal Beds. ■s 1 a of Coal by Mushet. The Coal described, and its Uses. 1 si 1 ■a 8 •1 , ButterlyPark coll ., lower hard coal ft. in. 61.14 .^4- 1 1 4-75 splint, blast furnaces. Chesterfield „ — 61.61; 3S.IO 3.2s mixed, good cleavage. '■% Double or Minge coal — 60.66 37-^4 2.00 bright, furnaces. -S Clod coal — 61.21 37. 2q I. SO smooth fracture. ft Buckland Hollow or Kilbum coal — i;8.62 40.00 1.38 .broad, smooth fracture. Moreley Park, cannel coal . , — 4S.00 45.0s q-q5 conohoidal. ■Cann«l coal near Alfreton works — 55.27 40.7 s 4.00 beautiful, specular. Low Moor, better bed 2 4 67.06 S2.IQ 0.7s dense, furnace and forge. !" „ black bed I 8 71.42 27.08 I. so friable, domestic use. :aJ Bowling, better bed . . ' . I lO 64.2 s SZ.SS 2.00 bituminous, farnace and forge. f „ crow coal . I 8 66. IS SS.«5 1. 00 distinct, with clod, sale. o Parkgate, main coal 7 67.14 30.73 2.13 four-feet, blast furnaces. Old Parkgate vein . 4 6 65.09 33-28 1.63 hard, in laminae „ FAT BITUMINOUS COALS OF YOEKSHIEE AND SCOTLAND. Analysis of 100 Parts 1 of Coal. By whom analysed and -g 1! i •0 Description and Locality of Coal Beds. Q Is .5 described. 1 En 1 ^ si 8 1 YOEKSHIEE. ft. in. Parkgate, top coal, upper part of the 7-ft. cl. D. Mushet . I 4 62.51 36.49 1. 00 „ bottom part .... II I 8 66.94 31-56 1.50 Birkenshaw coal . — 64.96 32.54 2.50 Worsboro' furnace coal . 91 • 9 o| 60.32 38.18 1.50 „ another specimen . »> 56.45 40.85 2.50 Milton, main coal, splint part JI 9 oi 69.40 27.60 3.00 „ roof or soft part . JJ 62.71 36.04 1.25 Thorncliffe, thin furnacn coal . 2 6 63.98 35-52 0.50 Smithy, wood coal . II 2 6 54.60 44-27 1-13 Easley Park .... 1» I 7 69.12 30.00 0.88 Yorkshire Kent coal I) S 66.40 32.72 0.88 Stafford, main coal, 5-feet, bottom part II 3 62.08 35-67 2.25 „ top part II 2 68.12 30.20 1.68 Silkstone, main coal 11 — 65.08 32.29 2.63 „ soft or clod coal II 5 63.10 35-15 1-75 SOOTLANU. Clyde, upper vein, top .... 11 ... — 37.00 41.50 21.50 „ „ bottom U . — 53-45 44.80 1-75 „ second vein 11 — • 42.10 48.34 9-56 „ third or furnace . M — 51.20 45.50 3-30 „ fifth splint coal . II . — 53-40 42.40 4.20 Calder, furnace coal, top II — 49.98 43.82 6.20 „ „ splint part — 50.67 47.48 1-85 „ „ main coal, top II 49.60 49-39 1. 01 ANALYSES OF COALS. FAT BITDMIN0U3 COALS OP YOEKSHIKE AND SCOTLAND- 741 Analysis of 100 Parts By whom analysed and of Coal. a 1 Description and Locality of Coal Beds. • ll c described. n 1 G 'v a is m H s| -.1 Scotland — {continued). ft. in. Calder, furnace coal, middle . D. Mushet . 52.30 39-95 7-75 ,, ,, bottom , n — 51.60 44-51 3-89 Glen Buck, furnace coal — 53-20 45.20 1.60 „ inferior coal )» — 48.80 44.20 7.00 Cleugh, furnace coal » — 47.08 42.25 10.67 Omoa, splint „ — 46.62 „ bright „ n ■ — — 47-29 Marystone, Pyotshaw coal, top if — 49.60 49-31 1.09 „ pine splint . „ heavy splint n — 51-82 46.57 1. 61 )) — 54.67 39-25 6.08 Fat bituminous Coals. Govan coal, first vein, top part „ . . . — 49-55 44.65 5.80 „ „ lower part JJ — 49-41 48.92 1.67 „ second vein )( — 42.20 48-34 9-46 „ fifth vein, splint . )j • — 48.84 49-79 1-37 „ sixth vein, lower main- _ I. Craw coal . i> — 51-58 44.60 3-82 2. Head coal . u — 48.08 49-38 2-54 3. Ground coal . )j — 44-57 51.00 3-43 4. Foot coal >) — 52.27 4415 3-58 Lesmahagow, cannel coal n — 39-43 56-57 4.00 Dry Coals, not very adhesive Clyde, splint coal . _, " ... — 59.00 36.80 4.20 jj j» Thomson — 55-23 .^5-27 9-50 , , clod coal . D. Mushet . — 70.00 26.50 4-50 ,, soft coal Tliouison — 42.25 47-75 10.00 , , near Glasgow DuiVenoy and Berthier . — 64.40 31.00 4.60 Calder )i — 51.00 45-00 400 Monkland ,, )> — 56.20 42.40 1.40 Middlerig . Dr. Fyfe . — 5°-5o 42.00 7.50 Scotch coal . W. R. Johnson . — 48.81 41.85 9-34 ,, cannel ji — 60.34 36-95 2.71 " " ■ • Dr. Ure . . . — 3940 56.60 4.00 Locality or Name of Coal. Analyst. li sit §1 ■so CO ft, Rochsoles cannel . Dr. Penny 1.448 .5.3-7 4-9 38.8 1.60 I.O 43-70 Hurdie's „ . . . 1.420 34-0 4.0 58-4 — 3.6 64.40 Boghead, brown cannel . J 1. 160 71.0 7-1 21.2 0.24 0-4 28.30 ,, black „ > 1. 218 62.7 9.2 26.5 0-35 1.2 35-75 Torbanehill cannel 1. 189 67.1 10.5 21.0 0.32 1.0 31-52 Boghead „ J 1.155 71-3 II-3 16.8 (0.34) 0.6 28.10 Balhville ,, I 1. 201 64-3 12.6 22.2 0.25 0.6 34.80 Stand, Airdrie, cannel . 1.464 52.0 14.7 32.0 I.I 46.77 Methill J 1.300 49.2 17-5 29.7 — 3-5 47-27 Capeldrae . , 1.360 45-7 19.9 31-5 — 2.8 51-47 Wemyss J 1. 183 58.5 25.2 14.2 — I.Q 39-53 Balbardie .... J 1.420 38.9 29.6 28.0 0.38 3-0 57.66 Billhead, Kjlmarnook, cannel } 1.602 1.320 36.6 32-3 27.4 0.61 3-0 59-74 Bi-ymbo .... , 32.1 36-4 29.4 2.1 6i;.8o Lesmahagow, Auchinheath . ' 1. 199 56.2 36.7 4-3 0-55 2.2 41.00 742 ANALYSES OP COALS. Locality or Name of Coal. Analyst. 11 mo HI ^li ^1 is, 2-4 "I OS Bartonshill .... ■ Dr. Penny 1.280 40.0 39-6 lO.O 2.CX3 49.60 „ . . SSo 38.0 37-9 18.7 2.20 .3-2 56.60 Stevenston, Ayrshire . SiiS 40.2 40.1 19-3 — 0.3 59-49 Lesmahagow, SoathfielJ 228 49-3 40.9 6.3 1-35 2.0 47-31 Knightswood 2,S4 44-7 41. 1 II. .3-0 52.18 Canibroe .... 247 42.8 42.6 8.S — b.o 51-17 Skaterigg .... 252 49-3 44.8 2..S — 3-3 47-33 Cowdenhill .... 2qq 46.0 45.0 5.0 0.50 S-S 50-00 Bredisholme :?,ss 39-0 48. ■; 8.1 0.40 4.0 56.60 Ruohill 223 4S.7 49.2 2.5 — 2.5 51-77 Kelvinside . 1. 213 40.1 53-4 1.9 0.21 4-3 55-32 ANTHRACITES OF EUROPE. Localities. By whom examined and analysed. i Analysis of 100 Fails 1 fi --.2 1 < 1 «1 i SoDTH Wales. Anthracites. Welsh anthracite, Cwm Neath Ynis Cfdwin, Crane ,, ... Dr. Schafhaeutl . Jno. F. Frazer . W._ E, Johnson . 1 1-336 1-372 1.368 1.409 1. 354 92.42 86.60 I 87.60 5.97 4.90 7-60 9.18 I.9I 0-93 5.80 4-32 Welsh stone coal . . . . Welsh slaty stone coal .... Mean of several varieties of Welsh coal . D. Mushet . Dr. Fyfe's experiment . 89.70 84.17 71.40 8-00 9.10 17.80 2.30 6.73 10.80 EuBOPEAH Continent. Anthracitous Coals. The Alps, IsSre, Canton of Launure Canton of Lanton, near Greuob:-e . Westphalia Mean analysis of twelve varieties of an- thracite .... M. Robin . M. Karsten .' '. ,, . . . Berthier 1.072 1.358 1.336 79-15 7-37 040 13-25 Dry or Slightly Bituminous Cocik. • Ireland. Kilkenny, Leinster .... „ slaty or cannel B.iolavoonein, stone coal Corgee „ . . -. Queen's county, Leinster Kilkenny, cannel .... )) ...... D. Mushet . „ . . . „ . . . Karsten Dr. C. T. Jackson 1.602 I.44S 1.436 1.403 1.403 92.88 80.47 82.96 87.49 86.56 74.47 79.60 4-25 13.00 13.80 9.10 10.30 25.01 12.00 2.87 6-53 324 340 3.14 0.50 8.40 Scotland. Coal, under basalt, Renfrewshire . Dalmellington, Ayrshire D. Mushet . Dr. Penny . 1.453 69.74 87.70 16.66 8.70 13.60 3-60 France. Mean of twelve specimens Ceted'Or, Sincey Mais Salze M. Berthier De Nerville M. Varin . : 79-15 82.60 83.00 7.17 8.60 7.50 9.50 ANALYSES OF COALS. 743 BITUMINOUS COALS OP FRANCE. Departments, Coal UasinB, and Varieties ol Coal. Locality. Coucessions. By whom araiysed. _J^ Analysis. 1 1 ii 1 a 24-77 ■3 Montet . . M. Baudin 1.38 ' 75-23 Gabeliers )j 1-34 74.92 25.08 *Basin of J Deux Chaises, Fina ] Chapelle ,, 1.48 74,22 25-78 Fins .... 68.28 3172 Koy.ant . M 1.30 62.49 37-51 *Basin of 1 Bussifere-la- v grue *BaBin (jf Bert 1-34 54.76 45-24 1.36 j 58.47 64.20 41-53 35-80 Commentry . M.Regnault — 63.20 36.60 1.20 *Basin of J Commcntry Chambled . . Marais . . . ji 1.38 87.85 12.15 Commentry . . Anienat 1.27 60.00 40.00 Neris Great bed . . ,^ 1-35 58.b7 41-13 5, Ferrieres . . ,, 1-31 56.76 43-24 Doyet La Souche . ], 1.30 61.23 38-77 *Ba8in of Monticq . Bourdignat jj 1.28 59-58 40.42 Dojet . , Chauvais . . ), 1.30 58.61 41-39 Bezenet . . Grand masse . 1.32 56.84 43-16 / New bed . i M. Baudin 1.26 66.60 30.19 4.60 Cliampagnac in the coal nn CI n nV Mines de Lem- pret . . 2 metres . 2 .... 3 Upper bed . 4 1-33 1.36 1.28 56.30 53-20 65.70 29.80 30-30 30.10 13.90 16.50 4.20 Haute- \ Dordogne — Cantal \ Mine de Madie ■ Fir-it or lowest bed . . 6 1.27 128 62.40 60.70 30.60 32.90 7.00 6.40 2nd bed 7 ,, 1.2B 64.00 31.60 4.40 Mauriac . . . Madie . . . M. Bertbier — 61.00 3450 7.50 / I. Messeix Oydance . . ,, 1-39 8549 "4-5I 2. Singles Morilleux . . j» 1.38 71.27 28.73 3. Lenipret . . New bed . 1.38 69.10 30.90 Coal Babin of Haule- / Dordogne — Cantal 4. Madie 5. Prodi'llcs. . 2nd bed . . 3rd bed . . . n 1.27 1.40 68.97 67.28 3103 3272 6 Vendes . . Cbamplaix. . 1.38 66.08 3392 7. Madie 1st bed . . . ,, I-3I 66.05 33-95 8. Singles Guinguette ,, 1.32 65.14 3486 9. Lempret C. de I'air . . n I-3S ' 63.08 36.92 Mandailles Lignite . . . 41-45 58.55 \ Chambenil . • 1.28 40.88 59.12 ^ I. Charbonnier Great bed . . M. Baudin 1-43 86.41 '3-59 2. LaCombelle 1.38 80.31 19.69 3- La Ronziere . ,, 1.36 78.82 21.18 4. Arnjots . . Fortainedu- Chien Cbamas >• 1.38 77-48 22.52 5 n 1.41 76.79 23.21 6. Gras Menil Great bed . . 1-35 75-3' 24.09 j-Anvergne, Central France, de- ( partment of Puy-de-Dome 7. Fondary Les Vignes )> 1.30 75-15 24.85 8. La Taupe . Arrest . . . 1.32 73-89 26.11 9. Megecoste . 6lbbedof4-ft. ,, 1-34 73-01 26.99 10. La Taupe . Great maps 1.32 71.80 28.20 II. Les Barthes 12 Basiard of 3-ft. 8-feet bed . . M 1.36 1-39 74.40 70.14 28.60 29.86 13. Megecoste . 7lhbedof8-ft. 1-34 70.09 29.91 14. Les Barthes 3-leet . . . ,, I -45 70.07 2993 15. Megecoste . 6-feet bed . . „ 1-34 69.86 30.14 16. Les Barthes 3-feet . . . n 1-35 68.64 31-34 17. Megecoste . 7-feet . . . 1-49 67.08 32.92 18. Les Barlhes Le Feu . . . „ 1-33 66.78 32.22 ^ 19. Brioude . . Preifisat " 1.32 59-43 40.57 * Coal of the Bourbuuuais, department of Allier. \ Goal basin of Brassac. 744 ANALYSES OF COALS. BITUMINOUS COALS OF FKANCE — (continued). Departments, Coal Begins, and Varieties of Coal, Basin of Brassac, mines of La Taupe and Arrest Basin of St. Kloy, or Montaigne Basin of Bourg Lastic Locality. NearGuinguette La Boche La Vernarde Messeix , . Singles . . Concessions. Singles . . . Agassiz bed . La Louise bed 4-feet bed . . La Felicity bed La Trouelle . Analysis. By whom ^ s^ analysed. § en 1 Q II 1 < M. Baudin 63.90 32,00 4.10 1-340 65.00 26.40 8.60 1. 310 68.50 26.80 4.70 1.320 66.20 27.00 6.80 1.300 67.50 26.00 6.50 1-330 66.10 26.30 6.60 1.300 59.80 40.20 5.20 1.300 60.40 39.60 8.70 1.390 86.24 13-76 5.20 1.380 75.00 25.00 13.00 1.320 68.00 32.00 8.20 BITUMINOUS COALS OF FRANCE, DEPARTMENT OP PUY-DE-DOME. Puy S. Gulmier DeChiex . . M. Baudin 1.340 84.45 iS-SS ■/■ La Besette . . Vazazene . . 1.280 66.75 33-25 — . MeJlifere . . M. Gruner — 74.00 28.52 Jumeaux . . — 68.7 s — 22.63 Sa6ne-et- Loire St. Strain . j „ 1st CISBS Vignes . . . — 68.75 7352 — 24.00 26.50 Qnafre Bras . — 66.80 — 19.80 St. Charles . — 69.25 — 22.10 Basin of Creusot and Blanzy Maillot . . . — 59-50 — 12.20 Conimunautfis . Montchjnin . . Longne Fendue " — 67.75 61.25 60.00 — 5-45 9.00 8.00 Eagny . . . — 63 20 — 8.SS \ Blanzy . . . Montceaux . . — 58.00 — 500 Lucy .... Lucy . . . — 65.00 — 14.00 Saone-et-Loiie Basin of Epinao Eegnault — 61. 10 36.40 2.50 Volx .... \ f 51.70 42.50 5.80 Dauphin . . . 49.20 46.30 450 Provence. Volx .... 39.20 4S-80 15.00 Dauphin . . . 34-70 S3- 10 12.20 Basses- Alpes Sigonce . . . 40.60 52.40 7.00 Manosque . . 31.20 50.50 18.30 Villemus . . . 38.90 SI. so 9.60 Pierre-vert . . Lignites . . M. Diday \ 28.00 4S.80 26.20 Cadiere . . . 48.10 44.80 7.10 Var St. Zaoharie . . 32.40 61.60 6.00 Beausset . . . 40.60 3940 20.00 Methamis . . 40.90 50.00 9.10 Vaucluse Piolenc . . . 26.60 41.50 51 10 52.30 22.30 6.20 Moutragon . . J V 36.80 48 20 15.00 Du Soleil. . . Monteel . . . M. Gruner — 74-59 19.60 2.81 St. Marie . . Chaney . . 1 „ — 74.81 21.67 3-52 St. Claude . . Meons . . I 11 — 74-31 24.17 1.52 *Ba8in of >* ,, . . 2 „ — 73-80 23-13 3-07 Saint St. Miirie . . Chaney . . 2 ,, — 73-78 24-33 I.8q Elienne Reveux . . . Reveux . . . — 72-73 22.83 4-44 St. Claude . . M^ons . . 3 — 72.13 24.47 3-40 Caraude . . . C6te-Thioli^re — 69-13 25.67 5.20 \ Grande oouche » — 69.27 24.50 6.23 du cros " Fat coals, very rich in carbon first class. ANALYSES OF COALS. 745 BITUMINOUS COALS OP PKANOE, DEPAKTMENT OP PUY-DE-DOME — [continued). Departments, Coal Basins, and Varieties of Coal. 2n(l class. Ordinary Coals of Saint Etienne 3rd class. Fat Coals, J longue flamme ] *Bouclies-du- Ehone f.4rdennes fBasses-Alpes 'Basses- Pyrenees *Lozere and Aveyron *Gard *Bnuches-du- Rhone Var jCoals in Arrondisse- ment of Alais, . Department of Gard Coal basin of Alais, De- partment of Gard Locality. Client. Vincent Deville St. Andre Pompe Vincent Montrambert Littes . . . Great bed . Lignites of Greasque S^uhvral . . Lauzanier . Bayonne . . Eosiera . Peyre lau Alais . . . Eosher Bleu Belcodfene . Collobriferes . La Grande Combe . Prescol Partes . . Bessdges . . . Champelauzon . St. Jean-de-Var lerisle St. Paulet . . Connaut . . . 1. Besseges . . 2. Saint Cristol 3. Grand Combe 4- Concessions. De la Eocbe B^rard . . De la Eoohe 5' 5. 3' 3. ;■ M6nns . . 7. Du Treuil 7- 7. Berard . 6. „ . Great bed, 1 1st quality J 2nd „ Beraudifere . . 1st quality. . Meneduhaut i Bleu. . . 2 Menette . 3 Maitre Jean 4 La Fortune 5 La Saoude . 6 La Eavette 7 Peat By whom analysed. M. Griiner Lignite . St.Chnstol,lig Great lig'te bed Smaller beds ) of lignite J Coal. . . . 1. Foumier . 2. Plnmb . . 3. L.Barraque 4. Abilon . , . 5. Velours 6. Bosquet 7. Eotnsohild 8. Levape 9. Trois-Ma- choires 10. Cinq-pans . 11. Taraniere . 12. Eowiere . 13. Great bed . 14. Champel- auzon 15. Eemise 16. Lignite 17- „ Coal . . . Lignite . . Coal . . . Pin bed . . M. Diday M. Sauvage M. Diday M. Gruner M. Cochon M. Varin M. Diday :: * M. Varin M. Varin M. Varin M. Varin M. Varin M. Varin Analysis. 67.96 66.66 65.72 61.05 66.35 65.68 62.89 58.81 63-71 6394 57.82 5456 58-79 59,29 48.20. 48.50 45.60 41.90 44.70 43-70 39.10 22.00 9.00 48.50 50.70 49.10 34-00 50.20 45.20 26 -50 63.00 76.00 70.00 80.50 81.00 75-00 74.00 73-50 77.00 77.50 78.00 65.00 78.50 67.50 79-50 72.00 36.50 35.00 68.50 34- 00 80.50 74.00 ^B 28.47 29.20 31.90 32-54 28.27 27.83 29-73 26.03 25-27 27-13 34.10 35-43 35-57 35.20 49.00 48.00 46.60 51.60 52.30 47.80 53-90 69.70 58.00 38.10 47.60 46.20 46.00 46.30 52-40 53-50 28.00 16,00 17.00 14.50 14.00 1400 20.00 16.50 18.00 18.00 19.50 18.50 1400 20.50 13.00 9.00 51.00 51.00 25-50 46.00 17.00 18.50 3-57 4.14 238 6 41 5-38 6-49 7-38 15.16 11.02 8-93 0.08 10.01 5-64 5-51 2.80 3-50 4.80 6.50 3.00 8.50 7.00 8.30 33-00 13-70 1.70 4.70 20.00 3-50 2.40 20.00 9.00 8.00 13.00 5.00 5.00 11.00 6.00 10.00 5.00 4-50 2.50 16.50 7-50 12.00 7.50 19.00 12.50 14.00 6.00 20.00 2.50 7.50 Lignite beds. t Peat. X Bituminous coals in France. 746 ANALYSES OF COALS. BITUMINOUS COALS OF riiANCE, DEPARTMENT OP PDY-DE-DOME — (continued). Departments, Coal Basins, and Varieties of Coal. Locality. Concessions. ! Analysis. By whom analysed. 1 11 CO ■5 1 II < 5. Beseeges . . Coal .... M. Variii _ 63.00 24.50 12.50 Coal basin 6. Grand Combe Plomb . . . 11 77.50 19.00 3-5° of Alaia, De- 7. Cessous .. . Mean of 3 exp. )• 78.30 1770 4.00 partment of 8. „ . . Masse bed,3 ex. I) 58.50 26.50 15.00 Gard 9- , "„ ■ ■ Salze beil, 2 ex. t1 83.00 7.50 9.50 Bochebelle . . M. Berthier ^ 68.00 21.60 11.40 / Concessions 2 M. Garella 56.50 17.00 26.50 of Bous- 3 }i — 77.50 19.00 3-50 H^rault SaintGervais basin . . quet'dorbe i 4 and Giais- 5 It — 70.50 69.70 16.00 15.00 13-50 15.40 sesac . . 6 11 65.20 18.50 16.30 Graissesac . . — 68.80 31.20 15-30 St. Gervais . M. Griiiier — 85.16 14.84 14.05 78.30 16.40 5-30 Paleyret, No. 3 . M. Senez — 67.50 26.60 5- 90 ,, " 4 ,, — 61.00 32.80 6.20 Bom ran . . . — 7'-S0 24.60 .i-go Fontangcs . . — . 63.00 27.20 4.20 Aveyron Basin nf Aubin,/ Fareiret . . — S3-00 38.30 8.70 or Ddtazeville Bouquies — 69.80 25.10 5.10 Cransac — 53-20 39-30 7-50 Lavergne . . — 50.00 42.00 8.00 r,e Poux . . 5500 38.00 7.00 \ Lagrange . . M. Eegnault 61.20 34-20 4.60 Tarn | Basin ■ of Car- Grand-Vein . — 72.60 23.60 3-80 nieaux . , Castillan — 74-50 20.90 4.60 M. Berthier 56.00 24.00 20.00 Aude \ Basin of S^gure M. Bois 60.00 22.00 18.00 M. Leplay 71.60 24.00 4-40 Basin of Durban M. Berthier — 49.00 3350 17.50 Anzin.bitumens Chevalier 1.284 74-25 25.00 0-75 Nord Basin of Valen- ciennes Fresnesanthro'e It 1.360 89.30 7.20 3-50 Anzin . . . Berthier 1.284 71-50 25.00 3-50 Haiile-Saone G^monval . . Corcelles&Lure M. Drouot 1.440 48.90 36.60 14.50 Vosgee Norroy ... M. Eegnault 1. 410 / Grand-Croix . ■ ■ ■ 1 1.298 1.302 67.20 68.80 31.00 29.80 1.80 1.40 Cimitiere . . 1.288 68.40 28.00 3.60 1.294 67.00 3000 3.00 Ehone Eive-de-Gier ( Couzon . 1.298 62.80 3450 2.70 1.311 62.10 32.60 5-30 Corbeyre . . 1-315 74.00 23.00 7.00 Couzon . . . M. Griiner 63-55 3093 5-52 Grezieux . . 1) — 62.54 25.10 12.36 V Couzon . . . ,, y. — 62.57 30.07 7-34 Doiilr? . . • Mnrtean . . M. Boyd — 29.50 53-50 17.00 ,A.f\J U\JO Flangebouohe . It — 30.00 62.00 8.00 Jura Orbagna . . t1 — 30.50 57-50 I2.00 ANALYSES OP COALS. 747 ANALYSIS OF COMBUSTIBLES, EUROPE. Departments, and Varieties of Coal. Loeality, Designation of Coal Beds. By whom analysed. Analysis. 1 % a ■« Deux Sevres Chantonnay . . Main coal . . . M. Boye 62.70 20.00 17-30 Vendee Basin of Voavant Faymoreau . . M. Berthier M. Sentis 61.15 65.10 58.50 2950 27.50 31.00 6.15 740 10.50 Loire Inferieure Ancenis . . Guignardifere . . Finisterre Plogoff. . . . Cap. Sziain . . II 63.00 25 -co 12,00 / Pits of St. Barhe . M. Sentis • 80.21 17.60 3 79 77-59 18.00 4.41 Layon et Loire . Du Booage and 82.39 13.20 4.41 Des Barres M. Lechatelier 67.03 16.60 16.37 The West . . . ij 69.92 18.00 12.08 France. Mont-jean . St. Nicolas . . )j 65.88 7376 23.40 22.34 10.72 390 Beau-soleil . . ]» 74.02 19.20 6.78 Coals of Maine ( et Loire St. Georges sur Loire ... The Arch . . >j 63.40 27.87 8.73 Chandfifonds St. Barbe . . . „ 73-57 10.00 16.43 1 .IICVIILIO I l^lJLtO . St. Nicolas . . ]} 71.78 11.60 16-62 St. Georges Conception . . )j 72.71 65.00 15.60 23.80 11.69 11.20 Chatelaison . Adfele .... )} 80.99 9.40 9.61 \ DuPavfe . . , 78.10 18.40 3-50 Dou6 . . . . De Minieres . . ,^ 65.28 27.80 6.92 Haute-Loire Basin of Langeac M. Baudin 74.00 26.00 7.10 Feroe Islands Suderoe I. . . Brown coal Durocher 24.50 37-5° 38.C0 Meissmer . Anthracite . . M. Kuhnert 70.19 14-34 15-47 Hesse Caesel _,.",, ■ ■ • Pechkohle . . . ,, 56.60 40.97 2-43 (Coals) Jlirschberg . . Habichtwald . . )) ... 60.83 57.26 38.36 35-41 0.81 7-33 Hirschberg . . Diy coal . . . 'J 66.11 31-13 2.76 Hespe Caspel j Habichtwald . . Lignite, passing to coal Inferior lignite . )) 54.18 42.49 3-33 »» » 52.98 42.10 4.92 (Lignite) j» Middle „ )> 54-96 41.84 3.20 Rifrenkuhl . . . Woody „ 51.70 47.01 1.29 Stillberg . . . Lignite ,. , " 50.78 42.27 6.95 D. Mnshet 25.20 72.60 2.20 Peat or turf . Marcher 65.00 22.00 1300 jj 37.00 48 CO 15.00 Southern Eussia ■ Cossack . . Don ... . Country of the Don best anthracite Voskressensky 94-23 — Tiflis Inferior . . . 63.64 — — Italy. Principality of Monaco Mentone . Earthy. . . . M. Diday 49.20 29.90 20.90 / Ciieva . One-yard coal I. T. Cooper 66.00 31.80 2.20 Spain. Emanuela . Three-yard coal . J, 67.90 30.90 2.10 Coah of Asturias 1 Viena Alfa Four-yard coal . Mine of Clause) . Del Kegueron M. Berthier jj 63.60 35.00 43.00 33-90 53.00 44.00 2.50 12.00 13.00 7.00 Mean of 5 other 53.C0 40.00 mines Tiidela . M. Pail'ette 65-80 3227 ^■')l Mieres . . » 57.60 39-40 3. CO Lama „ 56.69 41 51 I. So Oloniego . „ 60.40 36-55 3 -05 Amao . )> 45-69 45- n q.20 Ferrones . . " 46.98 46.91 6.11 748 ANALYSES OF COALS. BITUMINOUS COALS IN BELGIUM. Countries, Provinces, and Varieties of Coal. Province of Hainault. Near Mens Province of Li^ge. Dry coals GKEMANr. Bituminous Coals. Upper and Lower Silesia Saxon States Prussian Saxony Germany Saxony Bohemia Wiirtemburg Locality, Dovir Basin of Mons Canton of Dour Near Mons Li^ge Harion Chokier Bonnier Waldenberg . Sabrze . . Bielschowitz Leopoldinengriibe Friedricli zu Zawada Gustaw Griibe Salzer . . . u ... Circle of the Saale . . Brown coal . Eschweiler . Pottschapel . Planitz . . Elbogen . . Schlakenwerth Konigsbrunn Designation of Coal Beds. Plate seam Bouleau Grand Gaillet Gade vein . Ste. Marguerite Olisson . . . Cerisier . . . L'Harbe St. Michel Petite Hareng Moset seam . Glanz coal M. Canchy »j M. Chevalier t» Karsten Berthier C. Davreaux M. Delvaux Newark . fWettin or ) ] Wittenberg! Shraplau . Flotz Gyr . j» • Gate Schioht Pilch coal . Brown coal Carbonized peat Raw peat By whom analysed. Berthier Bichter Gay Lussac Karsten Gay Lussac Karsten Gay Lussac Karsten M. Balling M. Debette M. Berthier 1-307 1.276 1.292 1-273 1.263 1-307 1.270 1.270 1 = 1-365 1.286 1. 318 1.263 1.270 1.288 1.300 1-454 1.860 Analysis. 71-50 88.00 85.00 84.67 83.87 8550 71-50 6530 58,50 51.00 78.30 76.00 69.90 72.60 68.50 81.90 71.68 91-38 57.20 63.20 58-17 61.50 57-90 68.00 81.60 80.10 5670 20.25 82.40 80.23 41.00 63.40 37-18 67.00 24.40 2330 12.70 13-23 12.47 23-30 33-00 38.50 44.00 17.80 19.60 23.40 24.20 21.20 9.00 16.36 8.00 36.40 3-93 37-89 35-62 42 00 30.10 17.70 18.90 18.90 62.25 16.42 18.60 31-30 35.20 56.16 30.00 70.60 550 2.50 2.30 2.10 3-68 1-5 1.27 2.50 5-20 1.70 3.00 5.00 3-90 4.40 6.70 3-20 10.30 9.10 11.96 6.12 6.40 390 8.93 288 2.10 1.90 0.70 1. 00 24.40 17-50 1. 18 1. 17 27.70 1. 10 6.66 3.00 5-00 ANALYSES OF COALS. 749 BITUMINOUS COALS IN ASIA. Country.- HiNDOSTAN. Pres. Bengal Assam Pres. Bengal Birmese coast Turkey in Asia Syria Locality. Nerbudda Chirra Ponpje Kosya hills Prov. Delhi . Aracan . . Anatolia . . Mount Lebanon Mount Harmon Designation of Coal Beds. Fatepoor Slaty . Few ashes Hurdwar Heraclea . Asphaltum . Anti-Libanus By whom analysed. Prof. Hitch- cock I •447 1. 275 1.368 1.308 Analysi;!. 22.00 41.00 60.70 50.00 33-00 62.40 24.40 14.00 >^ 14.00 36.00 38.50 35-40 66.40 31-80 68.CO 72.60 64.00 23.00 0.80 14.60 0.60 5.80 7.60 13.40 ANALYSIS OF AMERICAN COALS. No. Locality. Description of Coal. Water. Volatile Matter. Fixed Carbon. Sulphur, Ash. I Virginia Nelson or Big bed, coking 0.932 20.738 73-728 0.618 3-924 2 Pennsylvania Lump coiil, Connellsville, do. . 1.260 30. 107 59.616 0.784 8.233 3 n Slack, do. do. . 0.950 29.662 55-901 I-931 11.556 4 " Pittsburg seam, do do. 31-360 59.620 0.784 8.230 S West Virginia New River measures, coking . 0.450 18,990 77-970 0.560 2.030 6 )) Do. do. do. 0.440 20.060 77-740 0,590 1. 170 7 )) Do. do. do. 0.380 20. 1 50 74.900 1,360 3.210 8 )) Do. do. do. . 0.360 20.760 76.890 0,640 1-350 9 „ Lower measures, do. 1.030 21.380 72.320 0,200 5.070 10 Do. do. do. 0.610 22.340 75.020 0.610 1.470 II Tennessee Upper do. (Rookwpcd), do. I- 750 26.620 60. 1 10 1.490 11.520 12 Colorado Laramie formation . 1. 140 29.970 56.320 12.570 13 '» Fox Hill group 0.720 23.440 71.910 0.360 3-930 14 Pennsylvania Lower Kittaning seam . Bituminous Coal of the Cahdba Cocd-fidd. 3.000 31-500 62.350 1.400 3-150 15 Alabama Cahaba vein .... 1.660 33.280 63.040 0.525 2.020 16 31 Holt's mine . 1.580 32.600 62.620 1.050 3.200 17 jj • Black shale vein 1. 910 32.650 63.910 0.630 1-530 18 )i Moglis seam .... 1.930 32.840 59.640 3.780 5-590 19 Little Pittsburg vein 2.050 32.470 62.200 0.641 2.280 20 ji Conglomerate no. 2.130 30.860 64.540 1.480 2.470 21 )) Helena do 2.540 29.440 66.810 0.528 1. 210 22 }} Coke do, . . 1.780 30.600 66.580 0.564 1.090 23 Gholson do. .... 2.140 31.920 63.680 2.260 24 „ Montevallo do. 2.130 27.030 66. 220 0.532 4.620 25 J) Gould seam . 1.340 28.960 60.580 0.820 9.120 26 )» Beaver dam do. . . . 0.300 31-360 65.450 0.080 2.810 27 )) Helena mines . 1.740 35-480 58.960 0.900 3.820 28 ); Wood's pit . 0.760 35-510 57-420 — 6-310 29 n Pushmattahaw bed 0.790 36.680 57- 2.30 — 5.300 30 Wadsworth seam . Bituminous Coals of Warrior Coal-field. 34-600 60.530 0.680 4.870 31 » Townley bed, lower part 3.007 29.084 63-352 0.710 4-557 32 JI Do. upper do. 2.960 26. 162 44.516 1-744 26. 362 33 I) Jagger bed, lower do. 2.238 29-037 50.638 0.360 17-987 34 !J Do. upper do. 3.091 29.041 56-537 0.574 11.328 35 Baker bed, upper do, 6-355 31.086 60.665 0.695 1.894 7SO ANALYSES OP COALS. ANALYSIS OF AMERICAN COALS — [continued). No. Locality, Description of Coal, Water. Volatile Matter. Fixed Carbon. Sulphur Ash. Bituminova Coals of Warrior Coal-field. 36 Alabama Baker bed, lower part 2.578 35-164 59-148 I-33I 2.910 H Phillip and Gordell bed (No. 3) 3.098 34-552 60.745 0.649 1.605 38 Do, (No. 2) 2.052 38.078 55-265 3.070 4.605 39 Jim Hawthorne bed (No. i) . 2.969 29.784 60.598 0.516 6.649 40 Sect. 4, Townsh. 16, Kange 6 W. 3-799 26.217 57-316 0.482 12.668 41 Do. 8, do. IS, dn. 2,213 28.987 56-454 0.586 12.355 42 Robinson bed, sample i (No. 2) 2.454 27.007 57.600 0.580 12,989 43 Do. sample 2 (No. 2) 2,703 26.600 56-367 0-599 14.330 44 Do. do. (No. i) 1.848 28.365 58-213 0.711 11-574 45 Beechy Hollow bed 6.952 27.065 55-640 0-527 10.343 46 Baley bed, sample i 2.702 29-564 64.818 0.690 2.916 47 Do. do. 2 5-715 28.095 62.612 0.603 3-578 48 Do. do. 3 1-533 30-405 51-962 1.236 16.100 49 Sect. 24, Townsh. i6,Eange7W 4-535 26.407 56.890 1.105 12,218 50 Village Creek bed, upper part . 4-175 22.415 62.482 0.521 10.928 SI Do. lower do. . 1-525 26.170 66.020 0.604 6.285 52 Newcastle vein 0.800 28.240 59-690 0.640 10.920 53 Black Cpeek vein, sample i 0.120 26. 1 10 71.640 0.100 2.030 54 Do, do. 2 1.360 31-796 64.710 0.320 1.820 55 Coketon vein, upper part 1.474 32.288 59-503 1.244 6-735 56 Do. lower do. 1-529 30.683 63-683 0.612 4.102 57 Fork Shoals profile, No, III. . 4.976 27.169 62.135 0-793 5,720 58 Do. No. in. , 1-475 34-271 59.128 1.131 5,126 59 11 Do. No. II. . 1.442 27.211 66.000 1.506 5-347 60 Do. No. II. . 1.398 30.647 62. 183 1.076 5- 772 61 Dt). No. I. . 3.560 26.566 64.288 0.722 5.646 62 Cane Hollow bed , 1.258 26.253 59.896 1.945 12,594 63 BlueCreekprofile,samplei,No, I, 2.514 32.093 61.886 0.801 3.507 64 Do, do, 2,No. I. 2.179 32-855 59.820 0.608 5,146 65 Do. do. i,No.II. 0.778 33-271 61.082 0.835 4.869 66 Do. do, 2,No.II. 2.391 33.865 59.069 0.798 4.675 67 Cannel coal, Daniel's Creek . 0.830 36-207 48-319 2.752 14.644 68 Block coal seam 2.239 34.606 50-375 1-613 12,780 69 Double do. . , , 1. 810 34.029 58.241 2.129 5,291 70 Manby seam . , . . 2.004 33-8.33 61.872 0.752 2.291 71 Universityseam.J.Black'sbranoh 7.285 28.989 54.522 0.765 9.204 72 Do. tJniversity mine 1-833 36.233 54-534 1.038 7.400 73 Do. Goiee bed 2.062 3'- 103 55-495 0.870 11,340 74 Prude's lower bed . 5.426 31-952 59-455 0.626 3.167 75 Chambers' mine . 1.838 30.682 64-339 2.380 3-141 76 MoLester shaft, near Tuscaloosa 2.2^5 35-130 55-301 1.861 7-324 77 Asylum do. do. 1.892 32.011 55-364 ■1.867 10.733 78 Burnett bed , 3-694 35-380 58-S17 1.730 2,409 79 Mineral charcoal . 1-753 15.285 79.215 3-747 80 Bituminous slate , 0.268 75.688 7.284 1.501 16.742 81 ■Warrior coal , . . . — 32-370 64.990 — 2.640 82 Woodwaid's coal, N.W, from Wheeling Kittaning Lower Coal Bed. 31.244* 63.458 5-318 83 Pennsylvania Glen White Coal Co, , 0.940 29.660 59-912 0.978 8,510 84 Ft Do, do. 1.040 28.010 49-244 4-501 17,205 85 tl Woodvale Bennington — 22.380 68.500 1.120 8,000 86 f Bennington shaft 1.400 27.225 61.843 2.602 6,930 87 Dennieon, Porter, and Co, 0.910 26.340 64-373 1.792 6,585 88 J, Cambria Iron Co. . — 20.330 70830 2.730 8.830 89 ,j Johnstown Manufacturing Co. 1.185 16.540 74.456 1.860 5.959 90 • South Fork Cambria Coke and Coal Co. 1. 100 17.240 73-145 2-352 6,163 91 It Dysart and Co, 0.615 17-935 76-503 0.602 4.345 * Including moisture. ANALYSES OP COALS. 751 AHALYSIS OF AMERICAN COALS — (continued). No. Locality. Desci'iptiou of Coal. Water. Volatile Matter. Fixed Carbon. Sulphur. Ash. Kittaning Lower Coal Bed. Llo^dsville . . . ■ 0.630 24.230 59-216 2.239 13.685 92 Pennsylvania 0.710 26.065 64.806 1.509 6.910 0.970 26.130 63.624 2.581 6.695 93 ,, Powelton C"fil and L-on Co. . 0.540 22.560 71-551 1.079 4.270 94 " Do, luwer bench Kittaning Upper Coal Bed. 0.600 22.600 68.709 2.691 5-400 95 J, Hale's . 0.740 25.210 68.628 2.122 3-300 96 ,, New Moshaniion I. 100 23.070 71.199 o.6n 4.020 97 „ Maple ton 0.700 23-565 68.890 1-715 5-130 98 ,, Laprel Run 0.800 23.260 72-350 0.590 3.000 99 ,, Derby, lower 0.410 22.810 66.690 1.790 8.300 100 )j Decatur . ... 0.640 24.360 64.082 3-378 7-540 lOI „ Do. . 0.820 23.900 69.007 1-373 4..900 102 ,, Ml .vrisdale 0.550 24.090 71.689 0.571 3.100 103 ,, Do. 0.560 25.190 ■71.013 0.587 2.650 104 0' Ji'hnstown — 16.580 76.870 0.472 6.550 X05 " Do. J-'Weport Lower Coal Bed. 1. 140 17.180 73-424 1.408 6.848 106 J, Penn 0.810 20.640 74-023 0.507 4.020 107 )) Franklin 0.670 21.360 74.284 0.435 3-251 108 ,, Do. — 20.100 76.390 0.190 3-510 109 ,, Euriika . 0.780 21.680 73-052 0.688 3.800 no >j Do. No. 2 1. 150 19.500 77.050 — 2.300 III » Webster 1.630 22.000 72.815 0.425 3-130 112 „ Stirling . 0.710 23.400 72.218 0-532 3.140 "3 " Moshannon . Dppier Freeport Coal Bed. 0.765 20.090 74-779 0.666 3-700 114 J' Coslnin . 0.160 18.630 74-950 1.400 4.860 115 Lilly Station . 0.715 22.250 70.518 1.459 5-058 116 )) Kittaning Coal Co. i.igo 26.975 64-359 2.728 4.750 117 n Dennison 0.960 26.400 65.586 2-274 4.780 118 1) Hugus, Somerset . 0.860 16.885 66.055 0.585 15.615 119 Rush, do. Pittsburg Coal Bed. 0.450 17.650 55-580 26.770 120 ,, Beachy . 1.680 21.010 69.016 0.764 7-530 121 „ Wilhelm 1. 190 21.000 66.907 0-713 10. 190 122 ,, Yoder . 1.465 21.285 69.677 0.693 6.880 123 ,, Livengood 1.665 22.350 68.774 1.246 5-965 124 „ Keystoae Coal Co. . 1.050 19.610 70.239 0.761 8.340 125 „ Cumberland Co. 1-385 21.470 69-352 0.763 7.030 I2J " Laylor Hill . Barren Measure Coal Beds. 1.630 19-965 66.510 0-775 11.120 127 „ W. G. Walker 1-945 21-935 68.544 1. 161 6.405 128 J, H. Coleman 2.010 20.535 68.321 0.744 8-390 129 )) S. P. Fritz . 1.625 22.700 67.467 0.803 7-345 130 -1) Weighley 1. 000 18.175 53-521 5-384 21.920 131 ,, T. Price 0.870 20.330 68.944 1.176 8.680 132 „ Ursina (lump) Do. (slack) 0.920 22.950 66. 999 3-096 6-035 133 n 1-555 23.480 63.483 4-037 7-445 Somerset County Subiasin. 134 )) Trevorrow's .... 0.670 14-530 74.800 0.635 9-365 135 „ "Wilts . ... 0.600 15-415 70.632 1.748 11.605 136 „ Reitz 0.940 19.060 70.659 1.291 8.050 •37 „ Zimmerman's .... 0.630 15-565 67.420 3-590 12.795 "38 » Nicholson .... Do 0.840 19.820 71.320 1-530 6.490 139 )> 0.500 17.660 51-430 3-110 27-300 140 )) Do. — 22.740 67.090 — 10.170 141 » Heinbach 0.780 20.540 69.580 j 2.140 6.960 752 ANALYSES OF COALS. SEMI-BITUMINOUS OE DEY COAL AMERICA. State and County, Locality. Designation of Coal Beds. By whom analysed. 1 o S ■§ D. ra Analysis. 1 Si p i .a Tennessee • Kentucky Cumberland Mountains Hawsville . Caseyville . Kimbrow's vein Gillenwaters . Splint or oannel coal Bituminous coal Dr. Troost . Dr. Jackson' Johnson 1.450 1.450 1.250 1.392 71.00 69.00 48.40 44-49 17.00 14.00 48.80 31.82 12.00 17.00 2.80 23.69 FAT BITUMINOUS COALS IN WESTERN VIRGINIA. STATE REPORTS. Locality. Designation of Coal Beds. Analysis. County. 1 is- II 1 < [Upper coal series.] Clarksburg . Main seams 56-74 41.66 1.60 )i ... 49.21 45-43 S-36 Pruutytown 57.60 39.00 3-40 Morgantown 60.54 37-30 2.14 ^ /Kanawha . I. Coal creek Judge Summers's bank . SS-5S 41.85 2.60 2. Grand creek . 52-75 43.20 4.05 >n Logan 3. Wolf creek, Big Burning spring . 47-15 48.00 4.85 r= Sandy river ■20 1 Kanawha . 4. Big Coal river . (Lewis') 50.20 47.10 2.70 S 0) \ ») 5. Three-mile creek Cartrell's . 45-95 50.30 3-75 ^ (.-• " 6. Elk river Friend's mines 55- 90 39-90 5.20 S" Logan 7. Logan Court-house . Lawson's . 5«-SS 39-50 2-15 ^ » 8. Guyandotte Traafork . 56.50 42.00 1.50 ^ „ 9. Big Sandy river Pigeon creek 55.00 41.00 4.00 MODERATELY BITUMINOUS COALS IN WESTERN VIRGINIA. County. Locality. Designation of Coal Beds. By whom analysed. Analysis. Is i < / Little Sewel 1 Wm-B. Rogers 80.24 17.48 2.28 X Mountain .0 jj 77.64 17-36 5.00 iz; £ Big Sewell Mn. Rogers's seam 75-88 22.32 1.80 SSt E. side W. flank Tyree's bed 67.84 30.08 2.08 ■^ri ^ » Deem's bed 71-73 27-13 1. 14 Fayette Mill creek . . Paris's bank 71.88 26.20 1.92 & Scrabble creek . . M 63-36 29.04 7.60 Bell creek . . W.B.Rogers' 60.92 32.16 37.08 2.00 r Keller's creek . Hansford's . State Report Second seam . . Storkton's min 3 ,, 74-55 21.13 4-32 Campbell's creek Euffiier's 2d sm 55-76 32-44 n.80 Lower coal series f) Nojes's seam 64.16 32.24 3-60 in the Valley 65.64 31.28 3.08 of the Kanawha Cox's creek . . 3rd seam . 51.41 42.55 6.04 Faure's bank Upper seam 53-20 35-04 11.76 L. Kuffner's bank „ 49.84 44.28 5-88 Bream's bank 3rd seam 57.76 33.68 8.56 I 54-52 29.76 15.76 ANALYSES OF COALS. ;53 MODERATELY BITnMIN0U3 COALS IN WESTKRN VIBOINIA — {continued). County. Locality. Designation of Coal lieiis. By whom analysed. Analysis. A II 1 u < Lower coal seiiea Hughes's baulc . W. B. Rogers' State Report 62.32 32.88 4.80 in ihe Vailev i of tbe Kanawha D. Ruffiier's bank Warth's bank . Upper seiim J) 57-28 54.00 35.08 39-76 7.64 6.24 Somi-Bituminous, or Dry. Montgomery Thorn's creek ■ . Strouble's run . Wm. B.Rogers 80.20 13.60 6.20 Lewisbiirg . . i> 78.84 14.16 7.00 Botetourt Catawba . . . 11 78.50 16.50 5.00 1 a Hampshire Brantzburg, N. 2 m. above m. of 72.40 19.72 7.88 S| br. Potomac Savage 1 Olwer's tract . . 12 feet seam . 79.08 16.28 4.64 O o )) Nr. Westernport Sigler's mine . 82.60 15.76 2.64 CJ ^ Maryland Lonaconing . . i2-reet seam . 77-43 19.37 3.20 Abraham's creek Macdonald's 3rd 74.00 18.60 7-40 1 ^ senm wj I mile from top Near Turnpike. 77.12 19.60 3-28 TS eS ot Alleghany ^ig Vandiivers . . N. W. Turnpike 61.44 14.28 24.28 £"-| Hardy Kitzmiller's . . 79.76 15.48 4-76 ^2=^ ,> Falls of Stony riv. Lower seam 79.16 15-52 5-32 ||l Abraham's creek Michael's . . 72.40 15.20 12.40 Stbny river . . N. of Turnpike . 83-36 13.28 3-36 K MichaePu . Upper part . . 45-24 14.96 39-80 S S Preston Kingswood. . . Fairfax's . . State Reports . 53-77 31-75 14.48 so n • • Middle seam . 65-32 27.77 6.91 §-■ u • • Korman's basin 73-68 21.00 5-32 =3^ Deck Hollow, c. Martin's . . . 65.42 23.42 II. 16 .S2 bo »' Bnifalo Lech run Beatty's . . . 62.56 29.60 7.84 -5 a „ Big Sandy . . N. Brandon's . 67.60 22.40 10.00 N. Brandonville Morton's . . 65.28 30.80 3-92 ^■2 S = " Cheat river, nr. Price's . . . 60.36 25.00 14.64 Kingswood 5 C ta " Big Sandy, W. side Seaport's . . 66.64 27.12 6.24 M'^ -' Kingswood . . Hagan's . . . 68.32 26.48 5.20 £«'i ,1 „ ' . . 67.28 29.68 3-04 S 1 O Big Sandy basin W. side Cheat . 60.04 26.88 13.08 £ Kingswood . . Cresaps . . . 64.24 30.24 5-32 J a South Bide Stonehenge . . Chesterfield . 58.70 36.50 4.80 ■^ (3^ James river i •"-3 ChesterBeld 2 Maidenhead . . Engine shaft . 63-97 32.83 3-20 2" « » 3 Hetb's pit . . " 62.35 37-65 2.80 S -a „ 4 Mill's and Keid's Creek pit . . 57-80 38.60 3-60 §1 „ 5 Wills's pit . . 62.90 32-50 4.60 >1 ., 6 Green hole shaft 67-83 30-17 2.00 g i „ 7 Heth's deep shaft Bottom seam . 53-36 35-82 10.82 W X. )> n Middle seam . 66. 50 28.40 5.10 fe c |» Top seam . . 61.68 28.80 9.52 ^1 " 8 Powhattan pits . Finney . . . 59.87 32-33 7.80 c| „ 9 "Winterpock crk. Cox's mine . . 65-52 29.12 5-36 » o Cloverhill, Appot- Slate coal . . Gr.W. Andrews 55.00 38.50 6.50 1^ tomax river "3" 2 ,, Mean of 4 spec. Johnson . . 54-83 33-04 10.13 «. ® o Richmond coal . Andrews . . 59-25 32.00 8.75 10.47 Bituminoi Chester rico Bar Mid Lothian . . Wooldridge's p. Johnson . . 61.08 28.45 • • Mean result, av. size coal n 53-01 33-25 14.74 Creek Coal Co. . Mean of 6 trials' . . 60.30 31-13 8-57 3° 754 ANALYSES OF COALS. MODERATELY BITUMINOUS COALS IN WESTERN VIRGINIA— (coB Third seam . . 65.50 24.70 9.80 ya i6 Fourth seam . 56.07 21-33 22.60 17 C rough's Lower Upper seam, 1 10 64.60 30.00 5-40 shaft ft. from surface a'S » Mean of 4 spec. Johnson, State 67.32 23.96 8.72 Report rlja i8 Scott's pit . . 60.86 33-70 26.80 S-44 18.00 ^1 19 Waterloo shaft . 55.20 20 Deep Run pits . 6Q.84 25.16 5.00 a a Mean of 40 spec. 67.96 2I-S7 10.47 ■«ja Wills's pit . . Dj)per vein . . T. G. Clemson 66.60 28.80 4.60 o « Anderson's pit . Bottom seam . R. C. Taylor . 64.20 26.00 9.80 ^'t Chesterfield . . Called natural W. B. Rogers' 80. so 9.98 9.72: §^ coke State Report a » I) ,, 70.00 16.00 14.00 5 )> Prof Bailey . 68.00 17.00 15.00 M )» Mineraloharooal T. G. Clemson 83-30 10.70 6.00 SEMI-BITUMINOUS OR DBY COALS IN THE STATE OP MARYLAND. - OR FROSTBUBG COAL REGION, OCCUPYING A SMALL PART OP -THE CUMBERLAND PENNSYLVANIA. Analysis. State and Locality. Designation of By whom 1 » ^ County. Coal Beds. analysed. V3 s SI 1 1 5 iSa < Pennsylvania. Somerset I. Hoyman's new 8-ft. bed W. R. Johnson 1-343 69.90 22.00 8.IQ J) 2 Uhl's upper »» 1-319 75-75 20.20 4.05 vein M 3. Korn's . . 11 1.386 68.46 20.10 11.44 )1 - 4. Schaeifer's . »» 1-370 70.70 18.80 10.50 IJ 5. Hoyman's 8 feet as above »» 1-363 71-50 18.30 10.20 » 6. Hoyman's 6 feet »> 1.362 68.54 19.80 11.66 )I 7. Uhl's 7-feet vein it 1.388 68.44 19.50 12.06 )» 8 Weller'8 4ft. )i 1.321 69.10 19.99 11.00 )) 9, Church land »» 1.480 68.56 18.70 12.74 vein IJ 10. Hardin's vein It 1.491 66.36 17.60 16.04 I -jS-j 69-73 19-59 10 68 the ten veins ANALYSES OF COALS. ;ss SEMI-BITUMINOUS OR DKY COALS IN THE STATE OP MAKYLAND — [continued). State aiid Locality. Designation of By whom if Analysis. s c County. Coal Beds. analysed. ' cd s ll to .a •s 1 6 II < Maryland Alleghany Maryland com- pany Hoffman's mine on main seam Silliman and Shepard 1.380 82.01 15.00 2.99 ti Cumberland coal Savage river . .. W.Hayes (Bos- ton) Dr. Jones — 77.86 15.60 6.54 )) 78.00 19.00 3.00 (Washington) "- )» " D. Jackson (Bnston) 1.321 77.09 16.05 7.06 „ Maiyland com- ,, Dr. T. P. Jones 1. 291 72.50 22.50 5- 30 pany (Washington) n ' • »> »' jf 1-333 81.00 15.00 4.00 ,, >) Frost's mine . Dr. Ducatel . 70.00 20.57 9.50 ,, Dan's mount . Av. of 40 spec. Johnson . . 1. 311 73-59 16.04 10.37 " Cumlierland coal Prof. Daniel . 66.30 19.40 14.30 )i Maryland com- Johnson . . I-43I 67.26 14.42 18.32 pany , 11 FrostburgNeffs )j ■ • 1-332 74-53 15-13 10.34 ,, Howell's estate Silliman . . 76.77 14.66 8-57 >i )' • ,. Prof. Etnwick — 81.00 13.00 6.00 u Easby's . . . Johnson I- 30s 77.25 16.23 6.52 " George's creek Main vein, Lo- naconing Dr. Ducatel . 1-386 79-25 »j it Third coal . . Foijrth coal . 11 1.552 1.584 80.08 85.00 „ Lonaconing company George's creek, thick bed Johnson . . 1.346 70.75 16.03 13.22 )) Maryland com- Eckert mine on »> 1-437 68.56 15.62 15.82 pany main seam Frostburg . Chilton . . . 77.00 78.80 12.00 9.47 11.00 "•73 n '* . * ■ Meanof2anals. Dr. J. Percy . — ,) Big vein . . 5 .- Dr. Higgins . 1.320 88.05 8.54 3-41 >. 6-teet vein . . ,- 5 » J) 1.340 86.01 8.68 S-3I M 44-inoh vein . „ S ., )i 1.390 74.24 7-13 18.63 „ OaUand . . 5 .. )i 1.290 73-34 12.54 5.12 FAT BITUMINOUS COALS IN THE STATE OF OHIO. County. Portland Jackson . Locality. Talmadge . . Lick Township Madison „ . Carr's Run Pomeroy . Desifmation of Coal Beds. Upson's mine . Cannel coal By whom analysed. W. W. Mather I) J. L. Gassels . R. C. T. . Dr. J. Percy 1.264 1.283 1.560 1. 410 1.270 Analysis. ^a 53.404 44.298 49 882 147 327 39.950 44.800 14.620 2.288 2.221 76.700 18.700 4.600 3 c 2 756 ANALYSES OF COALS. FAT BITUMINOUS COALS IN PENNSYLVANIA. County. Venango Beaver . Crawford Mercer . Locality. ShippensviUe . 6 M. F. of Franklin Greersburg Conneautville . Greensville Orange ville Namea of Coal Seams. Sandy Eidge By whom analysed. H. D. Rogers' State Report E. C. Taylor . State Report . Analysis. £■ a • "« 1 S .= "p — 49.80 43.20 7.00 — 29.54 52-78 17.68 — 30.12 36.00 33-88 — 59-45 ,38-75 1.80 — 57.80 40-50 1.70 1.275 — — — 53-45 43-75 2.80 MODBEATELY BITUMINOUS, DRY, AND CLOSE BURNING COALS IN PENNSYLVANIA. County or Locality. Designation of By whom f Analysis. 1 District- Coal Beds. analysed. 1 .2 1 1 / Blossburg . . Coal Eun, up- per vein Taylor and Clemson I-37I 75.40 16.40 8.20 „ Bear creek Clement's coal 1.398 73-74 15.00 11.26 J, BIosb's coal . » 1.405 73-00 15.60 11.40 ,, State Eeport . 62.80 32.80 5. 20 Tioga or „ Johnson's Splint coal Taylor and 1-493 69-30 14.60 16.10 Blosfbarg Bun Clemson Coal-field „ Coal Eun Slaty variety called Ciinnel " I- 750 3340 8.40 58.20 Pjtch coal . . 1-500 54-26 18.50 27.24 Head of Tioga New Hope vein E. C. Tavlor . 1.429 — Arbon company Coal run, mean Johnson . . 1-323 73-11 16.12 10.77 \ of 4 specimens Ealston and Lycoming Creek District Ealston . . Big vein . . State Eeport . Johnson . . 1-387 74-50 71-54 20.50 14-50 S.oo •3-96 Queen's Run . Av.of40 specim. State Eeport .' 1-331 73-44 73.68 18.81 21.50 7-75 4.60 Bradford or Schroeder, 1 Lower bed 1 fin three parts J 1 1-515 62-60 15.00 22-40 Towanda branch of To- W.R.Johnson ■( 1.448 70-00 17-40 12-60 Coal-field waOda creek 1.465 63-90 19.10 17-00 » Miller's old 1 coal drift J )i 1-377 1-378 68. lo 65.50 20.50 19.20 11-40 15.30 1-349 74-97 19.30 5.73 Mason's coal, )» upper part )» 1.388 — — — lower part 1.400 — — — Centre county Snow-shoe State Report . — 76.73 21.20 2-07 t) Farrandsville . Select portion of Diamond vein Bache and Rogers 1-339 — 5.50 State Eeport . W. E. Johnson 66.21 20.72 26.80 13-07 5-05 Clearfield county Kartbaus . . 1.263 68.15 M :. ■ ■ Salt Lick . . J* 1.292 1-275 80.49 76.64 12.83 22.27 6.68 5-09 J, Upper seam - State Eeport . 78.20 13-00 8.80 , Lower seam . „ — 70.50 24-80 4-70 Curwensviile . Eeed's vein . — 67.70 27.00 5-30 — 54-50 — Ci.6o 37.00 38.20 8.50 2.70 )) IJ •^ ANALYSES OF COALS. 757 MODERATELY BITUMINOUS, DRY, AND GLOBE BUENIsa COALS IN PENNBYLVANIA— ■{continued). County or Locality. Designation of By wliora & Analysis. d r District. Coal Beds. analysed. 1 6 s I ^ { Kartbaus . Mainor6-ft.sean W. R. Johnson _ 68.15 26.80 5-05 Piiilipsburg . Best coal . . W. R. Johnson 1.308 70.00 22.30 7.70 and R. C. T. »» ij State Report . Dr. Goddard . — 64.40 29.50 6.10 )) If 1.360 70.00 20.00 10.00 Moshannon / near ,, Sliowalter's 3- R. C.Taylor . 1-358 district 1 ft. vein »• n Guss's 6-ft. vein j» 1-357 »j )• Coal hill . . » 1.500 1 6 miles . . Steed's mine . State Report . — 68.40 20.40 11.20 \ i7i ., • . Leech's mine . )J — 67-93 20.32 11.75 Cambria Blair's Gap . Portage Kail E. T. G. Clemson — 77.00 15.00 8.00 J» )l Mineral diarcoal JJ — 66.40 6.60 27.00 )) »' Large Bed . . State Report . — 65.00 31.00 4.00 ■)■) Summit Portage Bail R. Johnson . . 1.406 69-59 21.36 9-05 Dauphin Short Mn. . South drift . . Dr.Ellet,R.C.T. J. C. Booth . 1-330 75-50 15-30 16.90 9.20 .3 ,j it Big Flats I M. C. Lea . . — 71.20 17.32 13.46 vein . . ' B. C. Taylor . I -395 > Rogers' Reports 76.94 15.06 8.00 >» J. C. Booth . — 15.80 00 I M. C. Lea . . I-391 78.80 13.20 8.00 c f? 9} KattlingEun Perseverance ' J J ■ • 76.10 16.90 7.00 Pk Gap . . vein . . 1 Rogers' Reports — 74-55 1375 11.70 "■ Johnson . . I-53I 72.22 14.29 11.49 'm mean of 6 exps. (5 Lebanon Yellow Back bone vein H. C. Lea . . '-389 74.70 14.80 10.50 CO Springs 1 J. C. Booth . — — 8.10 'e M. C. Lea . . 1-391 80.33 8.86 10.80 jj JJ Kugler vein -i JJ . ■ 81.20 9.80 9-30 is JJ ' • I- 395 77-50 11.00 11.50 ,| Rogers' Reports 1. 410 79-55 10.95 9.50 „ Cold Spring . Six-feet vein . H. Lea . 1.403 76-30 1 1. 10 12.60 m Bedford Broad Top M. Riddle's bank . Clemson 1.700 70.10 16.70 13.20 )» »» Hopewell . . Rogers' Reports — 84.80 11.20 4.00 » J» W. R. Johnson — 77-60 16.00 6.40 Dauphin Lykens Val- Bear Gap mines R. C.Taylor , 1.318 a ley M C ^ ist sample . . W. R. Johnson 1-391 87-95 7.60 4-45 u 2nd „ . , JJ 1.404 89.30 5-95 4-75 ■^ll JJ s^J „ • • „ 1. 416 85.70 10.00 4-30 's? ^->i JJ 4th „ . . !J 1-374 88.70 4.60 6.70 Mi'^ ,, 5th ,. . , JJ 1-376 87-75 8-35 3-90 S'|« J J 6th „ . . JJ 1-395 88.65 8.30 3-05 ■^^.'z JJ 7th „ . , JJ 1.382 87.20 7-84 4-15 2.= „ JJ 8th „ . . II 1-398 83-99 11.85 4-15 ■^■2 i JJ ?.* " • ,• ,, 1-378 87.00 7-30 .5-70 s'is „ Meanof gsmpls. „ JJ 1.390 87.36 8.06 4-57 *.S-3 >. Third Beb . . H. D. Rogers' 88.25 8.85 2.90 3 O Report CO SchuTlkiU Lower Mo- hantongo Klinger's or Bausch Gap J. R. Chilton, M.D. ~ 89.71 ■1-48 5.81 758 ANALYSES OF COALS. ANTHRACITE OF PENNSYLVANIA Analysis of 100 Parts >!. of Anthracite, Description and Localities of Antiiracite Coal Beds. -ff By whom examined 1 ii . or analysed S U3 Sis SI* Hard, White Asli Coal. 1 a Hi II" 2 /Mauch Chunk Olmsted . . . i-SSo 90.10 6.60 3-30 Vanuxem . . . 1.494 „ Summit Mines . W. B. Johuson . 92.30 6.42 1.28 . Karsten . . . — 86.00 8.00 6.00 It 11 • M. C. Lea . . — 87.00 7-30 5-70 1, 14-feet vein . . Eogers' Beports . — 88.50 7-50 4.00 Cj 1,,, 11 'ii hardest variety . ») — 87-70 6.60 5.70 Schuylkill -■ mean of 2 results Dr. J. Percy . . — 92.60 5-15 2.25 J!;aHterii * Begion Nesque honing ...... Taylor. . . . I-SS8 „ lo-feet vein . . Bogers' Beports . — 86.60 6.40 7.00 Taniaqua vein, D. east . M. C. Lea . . — .91.00 5-50 3-50 D Bogers' Beports. I-.S70 92.07 5-03 2.90 M E. „ . . . j> 1.600 89.20 4-54 6.26 „ B. „ . . . )j I- 550 f^-45 7- 55 5. Id Tuscarora . . „ — 88.20 7.50 4-30 \ Forest Improvement, av. or4siiec. Johnson . . . 1-477 92.12 .4-83 3-05 Hazleton Taylor. . . . 1.550 Sugar Loaf Mountain . . . j W. B. Johnson 3 samples I-591 1-574 1.550 88.18 85-91 90.70 6.99 5-36 7.06 4-83 8-73 2.24 Middle / Beaver Meadow Taylor. . . . 1.600 Coal-field W. B. Johnson . 1.630 85-34 9.60 5.06 » .... J) 1.560 91.64 6.89 1-47 „ ... . . » — 92.30 6.42 1.28 Girardville Taylor. . . . 1.600 VBroad Mountain, W. W. Branch ,, .... 1.700 Pine Grove Big vein, Lorberry creek . . . „ . . . . 1.472 District >i )j ' ■ . ' M. C. Lea . . — 85-90 7.20 6.90 Locust Mount Coal and Iron Co. Blake (Boston) . — 96.77 — 3-33 Bed Ash coal Sharp Mountain Rogers' Beports . 1.540 80.57 7-15 3-28 / Black Spring Uap, 4-feet vein . Taylor. . . . 1.528 » :) ■ Rogers' Reports. 1.440 82.47 9-53 8.00 „ Peacock vein . . Taylor &M.C.Lea — 88.60 7.10 4-30 Bed Ash— „ Grey vein . . M. C. Lea and Taylor 1-379 I -395 86.00 4.50 9.50 free burn- „ the black compact Rogers' Beports . 1.440 81.02 9.78 9.20 ing coal. part ■with slight „ the grey central » • I 330 81.40 11.40 7-20 flame. part — ' „ Fishback vein . . M.C.Lea . . — 84.00 6.50 9.50 Stony Creek ., Lea vein . . . Bogers' Beports . 1-350 85.84 8.96 5.20 Estate, Le- Gold Mine Gap, Peacock vein . M. C. Lea . . — 83.00 9.00 8.00 banon Co. )l u Bogers' Beports . 1. 410 83-15 10.95 6.90 First Goal- „ Heister vein . 1) • 1. 410 81.47 10.43 8.10 field Bausoh Gap „ Pitch vein . . . M.C.Lea . . R. C. Taylor . . 1-387 1-454 78.90 11.00. 10.10 Heister vein . . ■ M. C. Lea . . — • 77.10 10.90 12.00 V I Bogers' Beports . 1.450 77-23 10.57 12.30 /Broad Mountain Dr. C. T. Jackson 1-593 — 7.80 White Ash Lehigh or Summit Company, ist W. B. Johnson . 1-613 87.48 7-51 S.oi CoaL „ „ and j» 1-594 91.69 4-31 4.00 - J „ „ 5th 1. 612 86.06 9-23 3-71 South and Mauch Chunk Dr. J. Percy . . — 84.98 4.82 10.20 Middle Coal- Buck Mountain W. B. Johnson . 1-559 91.02 5-90 3-o8 field Shamokin (Snyiler's) .... Bogera' Reports . 89.80 6.10 4.00 ''West Mahanoy Taylor. . . . 1-371 ANALYSES OF COALS. 759 ANTHRACITE OP PENNSYLVANIA — {continued). Description and Localities of Anthracite Coal Beds. Hard, White Ash Coal. 6j whom examined or analysed. Analysis of loo Farts of Anthracite. •-" a"— 1? ^^ CDS'" Wliite Ash Coal. North or Wyoming Coal-fieU Bed Ash Coal. Potts ville District. First or South Coal- field / VVilkt-sbarre, Blacksmith's coal „ Warden's vein Wyoming Lackawanna .... ,, mean result . Scranton anthracite ^Carbondale Peach Mountain, Delaware Co. . „ mean of^o spec. „ N. American Co, Peach Orchard Salem vein I PliimbRgo vein, Sharp Mount . Black Mine vein Gate vein Slienoweth vein \Nealey'B Tunnel, 3rd vein . . Taylor . . . Rogers' Reports . J. F. Frazer . . Dr. C. T. Jackson Johnsbn . Prof. H.D. Rogers Rogers' Reports . Taylor. . . . Johnson . . . Dr. C. T. Jackson Taylor . " . . . H. Lea . . . Dr. C. T. Jackson Rogers' Reports . 1.472 1.403 1.609 1. 421 1.404 1.446 1.464 1.569 I-S32 1-574 1.412 i.6og 1.500 I-5SO 23 86.09 88.40 94.10 89.20 7.68 4.50 9.20 6.36 7.07 6196 6.80 1.40 5.40 3-49 4-30 11.60 4.66 2.70 6.95 7.20 6.60 4.80 6.60 4.50 5.40 ANTHRACITES OF THE UNITED STATES. Details. Analysis of 100 Parts Description of Coal Beds. of Anthracite. 6' 2 i By whom examined or 1 m analysed. s 6 sTgS %Si State. Locality of Mines. 1 ^ I <5 Rliode Island . Portsmonth mines .... Dr.C.T.Jackson 1.850 85.84 10.50 3-66 '• 1.770 87.50 77.50 84.50 7.00 13.00 10.00 5-50 9-50 5.50 11 >J L. "Vanuxem . — 90.03 4.90 5.07 91 II ,, — 77.70 6.70 15.60 Cumberland „ IJ n Dr.C.T.Jackson — 77.00 39-70 7.60 7.80 15.40 52.10 Providence ,, ,, — 72.00 28.00 Portsmouth old mine ,, — 74.00 10.00 16.0Q Case's mine . . — 97.00 3.00 Massachusetts Man .field mine 1.690 87.40 6.20 6.40 II 11 " 1.780 1. 710 92.00 92.00 6.00 6.00 2.00 2.00 Worcester plumbaginous mthrac. Dr. J. Percy . — 28.3s 3.08 68.57 North Carolina Near Leakesville, middle second- ary rocks W. B. Rogers . ~ 83.12 7-76 9.12 *England . . B rrowdale L. Vanuxem . — 83-37 1.23 10.40 *Pennsylvania Bustletowu • Plumbago . ^ ,, — 94.40 0.60 5.00 *England . . CornwiiU Saussure . . — 95.00 — 4.00 * Mr. Vanuxem adds, by way of comparison, the analysis of three varieties of plumbago or graphite. 76o ANALYSES OF COALS. BITUMINOUS COALS. State and County. Indiana : — Parke counts Vermilion . Vigo . . . Sullivan . . Fountain Spencer . . Illinois Iowa . . IMlSSOUEI Arkansas Maine . . . Miscellaneous Analyses. IsleofCiuba . Locality. Sugar creek . Brouillet's creek Honey creek . Busseron . . Wabash . . Anderson creek White river . Terre Haute . Cannelton . . Rock river Vermilion ■. Western port . Ottawa Rockwell . Duck creek Cote-sans dessein, Calloway co. Lick Fork . Coal creek mouth je river . Johnson county South America Madeira Island Bkit.Amekica Bituminous coal Nova Scotia . Cape Breton . Near Havana . Near Matanzas Peru . . Chili . . Brazil . . Designation of Coal Beds. Foundry Cannel coal Coal . . Danville . Brown coal Pictou . . Sydney . . W. bank of the Mississippi river Mastodon vein, forty-six feet thick . . Mammoth vein, twenty-four feet Spalpre's 'bluff Peat . . . Asphalt Asphaltum Coxitambo Arauco . . By whom analysed. D. V. Owen W. R. Jolinson Dr. U. D Owen A. Morfit . . Johnson _ . . J. F. Frazer . C. U. Shcpard Dr. D. D. Owen Booth and Boye J. R. Chilton, M.D. . . Or lignite Cunard's sample MiningAssocia'n Mean of 2 species W. R. Johnson J. F. Frazer . Dr. Jackson . T. G. Clemson I) M. Boussingault W. R. Johnson Karsten J) ■ Johnstone . Johnson 1. 219 1.270 1.240 1.240 1.260 1.270 1.270 1.240 1.272 1.340 1.290 1 .273 1.270 1.252 1.250 1.200 1-396 1. 190 1-324 1.289 1.483 1-325 1-318 1-338 Analysis. 75.00 52.00 70.00 70.00 60.00 45.00 56.40 50.80 59-47 45-5° 48.50 62.60 46.50 48.50 46.83 50.81 50.78 51-16 62.60 21.00 34-97 67.62 57-9° 38.10 60.73 56.98 67-57 21.00 39.00 27.50 28.00 25.00 36-59 44-50 47-20 32.80 35-50 47-50 44.00 40.05 34-06 34.20 43-50 28.90 72.00 63.00 30.00 40.50 33-50 26.76 29.63 26.93 4.00 9.00 2.50 2.00 25.00 3-94 10.00 4-30 1.90 6.00 7-50 13.12 15-13 15.02 5-34 8.50 7.00 2.03 13-50 2.38 2.60 28.40 20.05 12.51 13-39 5- SO ANALYSES OF NEW ZEALAND COALS EXHIBITED AT INDIAN AND COLONIAL EXHIBITION, LONDON, 1 886.* Description of Coal and Locality. Water. Volatile Hydro- carbons. Vixed Carbon. Ash. Evapo- rative Power. Anihracitf! from Acheron, Canterhuiy . Altered brown coal, Malvern Hills, Canterbury Brown coal, Malvern, Canterbury „ ( Homebush Colly.) Malvern, Canterbury Glance coal, Rakaia Gorge, Canterbury Brown „ „ „ 1.80 4.15 12.65 11.79 19.20 6.76 24.09 2.06 19.89 32.04 35-42 30,92 21.27 21.61 84.12 68.54 53-29 49-99 47.70 64.51 50.12 12.12 7.42 2.02 2.80 2.20 7.46 4.18 5-17 8.87 6.92 6.49 6.20 8.30 6.50 * See " Jour. Iron and Steel Inst.," vol. i. 1886, p. 246. ANALYSES OF COALS, 761 ANALYSES OF NEW ZEALAND COALS- Volatile Fixed Carbon. Evapo- Description of Coal and Localitf. Water. Hydro- carbons. Ash. rative Power. Bituminous coal, Grey River, Weatland 1.99 29.44 62.37 6.20 8.01 Pitch coal, Black Creek, Grey River, Westland 801 29.97 60.20 1.82 7.82 „ Grey River, "Westland 6.20 55' 40 34.80 2.60 456 Bituminous coal. Preservation Inht 4-33 20.69 60.88 6.19 7.91 „ Westport . 3-97 32.14 59-75 4.14 7.76 „ Mokihinui, Westport 3- 16 38.86 55-59 2.39 7.20 Brown coal, Westport . 2.60 37-17 56.01 4.22 7.28 J, J, • • • 3-96 34-94 57.92 3-18 7.50 Bituminous coal, Brunner mine 1-59 35.68 56.62 6.11 7-36 „ Otamatawea Creek 2.19 36-63 52.89 8.29 7.90 Black coal, Kawa River 4.18 42.63 50.15 3-04 6.52 Glance coal, Whangaree, Auckland 8.01 3868 50.11 3.20 6.50 Pitch coal, Kama Mine, Whangaree, Auckland 9.61 37-69 50.01 2.69 6.50 Walton's „ „ „ 7.20 41.20 38.80 12.80 4.96 Blown coal, Waikato, Auckland . 19.82 29.97 50.01 2.20 6.50 Bituminous coal, near Cape Farewell 2.18 43- '7 48.59 6.06 6.63 Brown coal. Shag Point, Otago . 19.20 30-10 45-30 5-40 5.66 „ Eaitangata „ 15-44 38-32 44.11 2.13 5-74 i> ij jj 19.61 27.2s 39-41 3-73 5-12 Bituminous coal, S. of Rosa, Southland 6.58 31-43 42-53 19.46 4.16 Brown coal, Okoko, AVaipa, Auckland . 22.21 33-74 39-83 4.22 5-17 „ Springfield Colliery . 18.60 31-50 38.00 II. 90 4.90 For remarks on the coal-fields of Australasia, see " Jour. Iron and Steel Inst.," vol. i. 1884, p. 219. ANALYSIS OF NEW SOUTH WALES COALS. Locality. Hygro- scopic. Moisture. Volatile Hydro- carbons. Fixed Carbon. Ash. Sulphur. Specific Gravity. Lake Macquarie . 3-8o 23.90 55-50 6.80 Goulbum . ... 2.18 30.98 58.04 8.80 0.228 1-35 Goose Valley . ... 3-60 29.70 59-70 6.96 0.050 1-34 „ „ ... 3-66 30.38 54-46 11.50 0.062 1.38 Dora Creek . ... 3-04 17-76 62.10 17.10 0.142 I 44 2.52 3048 53-36 13.64 0.140 1.43 Wangenderry .... 1.74 31 06 52.00 15.20 0.300 .-38 Bowenfels 245 28.55 48.56 20.44 — 1-33 Ulladulla . ... 1.50 3304 57-40 8.06 1.110 I-3I 1.76 32.06 56-38 9.80 1.240 1-35 Capertee 3-25 2541 60 24 11.10 0.390 I 39 ANALYSIS OF COAL FROM ZWICKAU (sAXONy), BY BEtrCKNEE. Locality. 100 Parts of Dry Combustible at 212° P. yield : Raw Com- bustibles contain Water per cent J 1 S 1 1 i c 4 < Russkohle Burgerschacht . Pechkohle „ Auroraschacht . 82.10 80.00 73-85 5-34 5-50 4.70 0.65 0.88 0.60 0.37 0.40 0.48 10.45 11-54 14.10 1.09 1.68 6.97 8.00 8.00 6.00 762 ANALYSES OF COALS. ANALYSIS OF COAL FROM HUNGAEY, BY NENDTVICH. Locality, 100 Parts of Dry Combustible at 100° C. contain : .511 ^6 3 1 1 1 1 1 l« 4 < Comitat Crassoe -.— Pit, Heil Dreifalt „ Anton and Joseph „ Emilia .... „ Von Resicza Comitat Bakam y andTokay: — Fiiiifkirchen, Makay . „ PaulovicB Comitat Gkas and Comokn : — Funfkirchen, Magyaros Ujlalu . 83.84 81.57 78.37 88.72 89.99 88.8s '69.21 69.72 4-36 4.41 3.92 4.66 4.23 4.23 4.50 4.82 0.38 0.87 0.74 0,86 1.89 0.99 3.07 S.io 11.79 14.01 17.70 6.61 5. 78 6.92 26.28 25.45 8.24 2.26 0.89 18.23 2.85 8.34 9.74 3.19 3.21 7.30 1.20 1.22 1. 14 13.63 13.60 78.07 69.98 70.60 78.85 89.40 83.14 56.84 60.26 1.390 1.319 1.366 1.295 1.414 1.300 1.420 1.430 1 ANALYSIS OF COAL AND BROWN COAL FROM HUNGARY, BY NENDTVICH. Locality. icxj Parts of Dry Combustible ^1 Contain : Leave : 1 'a i 1 >- 6 < 1 HuNOAEY : — Coal, Baranyer Comitat, Rosman's ' pit 86.88 4.37 8.74 10.690 86.47 — 1.356 „ Do., Andrassevich pit, Funf- kirchen .... 88.30 4.80 6.90 5.820 82.82 1.313 „ Barbara pit, Szabolcs . 89.69 S.03 5.27 10.330 81.55 — ' 1-350 „ Francis pit „ 83.76 4-97 11.26 10.415 77.81 — 1-378 „ Michael's pit, Vassas . 88.76 5.04 6.Z0 9.910 76.82 — 1.291 „ University domain, Vassas . 86.72 5.09 8.19 12.050 78.57 — 1-339 „ Purkaripit,Cras86erComitat 8S.29 5.05 9.65 1.605 73-11 — 1-317 „ Gerlistye pit „ 85.48 4.92 9.59 2.39s 70.96 — 1.282 „ Markus pit „ 84.54 4.96 10.50 2.615 68.17 — 1.287 „ Simon and St. Antony pit, Crassoer Comitat . 82.54 4.3s 13.10 10.530 76-33 — 1-423 Brown Coal, Tokodt p [ 67.49 4.70 27.80 10.990 68.70 — 1.494 71.55 5-19 23.25 5.660 — — 1-359 „ Saris^p '^"™'™'' ( 67.85 4-93 27.22 9.410 61.23 — 1-403 „ Zsemle,ComornC(imitat 71.89 4.79 23-31 4.350 59-55 — 1-347 „ Eudolphi seam i fc 70.84 4-71 0.91 24.44 2.390 50-89 18.68 1.285 » ^i^-^] 72.18 5.18 O.S5 22.63 2.080 55-98 17.00 1.300 „ ^ loseph „ 3 S^ 72.49 .5-17 1.30 22.33 2.255 53.00 17.82 1.289 .. 4) <5 71.36 5.09 1.63 23.54 4.645 46.00 17.10 1-334 ANALYSES OF COALS. 763 ANALYSIS OF WOOD, TURF, AND BROWN COAL FEOM SAXONY, BY BAER. 100 Pans jrDry Fuel contain : Water per cent. S , lost at 100° C. Kind of Fuel. g a § . by Fuel in c ■a &? <» Narural •a 1 h Condition. Birch wood 48.89 6.19 43-93 0.99 13-14 fied beech wood 46.10 5-79 — 46.87 1.24 14.4 to 13.6 ,, ,,..... 48.29 6.00 — 45-14 0.57 13-7 White beech wood .... 48.08 6.12 — 44-93 0.87 12.8 Oak 48.94 5-94 — 43-09 2.03 8.0 ........ 48.63 5-94 — 44-75 0.68 13-7 Pine, young stems .... 50.62 b.27 — 42.58 0.53 12. 1 „ old floated sterna 49.87 6.09 — 43-14 0.63 II. 9 Turf, from Bucbfeldt and Neulangen, ist kind . 51-54 4-69 33-90 9-87 15-7 „ „ do., 2nd „ . . . 50.13 5-36 35-24 9-37 21.7 „ „ Flatow, 1st kind 50-36 4.20 34-27 11.17 18.4 I, „ Linum, and ,, 53-69 4-84 31-73 9-74 16.4 ,. „ .. 31'd .. 55-01 4-63 31-44 8.92 18.9 Brown coal or lignite, from Schonfeld, near Aussig, Bohemia 61.20 5- 17 21.28 12.35 21.2 Do., from Fiirstenwalde, Eauen, moulded 55-59 4.16 19.06 21.19 II. ANALYSIS OF GERMAN COALS. 100 Parts of Coal contain ; 1 a §■3 E'S Locality. 1 M TS w 1 1 C3 •i. 1 s II Hesse : — Coal from Meismer 82.00 4.20 5-90 3-90 4.00 1-307 — n n 62.18 5-47 18.05 9-30 5.00 1.208 — " TT. " ■ , 58.90 5-.S6 21.63 6.64 7.50 1.079 — „ Jdirscnbeig . 72.90 5-70 18.40 0.70 2.30 1.289 — p it ^11 62.90 5.70 17.00 7.80 6.60 1.050 v' „ V aulback 60.60 5-50 18.40 8.00 7.50 1-130 — s „ Gluokaul, near Mul hous 5 36.65 3-84 12.32 — 47.19 2.500 — 36.56 5.00 II 25 — 47-19 — „ Gallery d Oppel 62.00 4.40 10.06 — — 6.25 6.75 » )) 62.35 4-50 11.90 — — 9-05 7.20 )) M 61.85 4.40 11.85 — — 15-30 — 7.60 „ Gallery de Doehlne r 61.10 9.10 4.50 — — 8-5S — 6.75 )j " 60.10 11.00 4-45 — — 12.25 — 7.20 It " 54.20 9.10 4-45 — — 24-95 7.60 bo Anthracite, Schoenfeld 64.68 5-31 21.316 — — 8.65 „ Groespriessen 63-56 4.81 25.12 — — 6.51 — . s Coal, Grosspriessen 74-57 5-33 12.65 — — 7-45 — - - ^ jj » 70.95 5.18 13-55 — — 10.32 — — I) 66.86 4.81 "-74 — — 16.59 — — li 11 73-36 5.41 10.92 — — 10.31 — — „ „ 68.39 5.0b 12-55 — — 14.00 — " 58.68 4-48 9-83 — — 27.01 — — 764 ANALYSES OF COALS. ANALYSIS OF GERMAN COAL BY W. BAER. icx) Parts of Dry Combustibles at 212° F. yield: i n ^3 Locality. g 1 1 ^1 Sig •S il S a- S ■< ^6 Sii.ESiA : — Pit, Kon. Louise, Poohhammer seam 77.25 4.98 — 13.86 3-91 3-32 „ ., Bsdea 82.72 5.0s — 10.67 1.56 3.00 „ Hoym 72.96 4-38 — 12.12 10.54 4.80 „ Graf Hochberg . . • v 70.87 5-&S — 14-35 9-15 3-64 „ Neue Heiiiriuh 80.82 4.96 — 8.14 6.08 2.21 „ Fuchs . ... 79-3° 5 06 ^ 10.56 5.08 3-95 „ Ddvid . , . . . 79. i« 4-55 — 11.08 5-19 4.70 „ Segen Gottes . .... 82.02 5.22 — 1025 2.51 3-97 Westphalia : — Zeche, Eunstwerk ... . . 89.58 4- .SO — 404 2.08 1.29 „ Sabyer unJ Neuak 85.62 4.6S I 71 7.64 2.09 1.29 „ Hundsnacken 88.21 3.86 3-69 4.22 1-33 „ Victoria Matthias 86.4s S-32 — S.-67 2.58 1.66 Saxony : — Zeche, Von Lobezun ... 81.88 3-68 — .3-65 10.79 0.71 „ Wettin. .... 77-53 S-13 — S-30 12.04 0.82 Saakbeuck : — Pit, Gerhardt, Benst seam .... 72.38 4.46 — 15-05 8.11 5-77 „ „ Heiiirich seam . 70.20 4.70 — 13.27 11.83 S-27 „ Duttweiler, Beyer „ . 81.29 S-30 — 8-54 4.87 2.24 „ „ Natzmer , 83-6S 5.19 0.60 9.66 1.52 1.87 „ Heinitz, Bliicher , 80.53 S.06 — II. 91 2.50 2.31 Aster 78-97 5.10 — 13.22 2.71 2.45 DUKEN : — Pit, Centrum, Gyr „ . 90.62 4.50 — I-3I 3-57 1.26 i^omegel 84.06 4.27 — 2.22 9-45 1. 21 „ „ GroBskohl „ ... 8S.69 4.07 1.25 8.25 3-99 0-97 „ .lames „ „ . . . 89.48 429 3-98. 2.25 1.07 „ A,ih, Grosalangenberg seam 90.41 4-03 — 4.11 1-45 1.50 „ Neulauerwegi Grossathwerk seam 89.32 3.80 — 2.71 4.17 1.48 „ „ Furth seam 88.59 4.10 — 4-39 2.92 ■■31 ANALYSIS OF COAL FROM SARDINIA, BY ABBENE AND ROSSI. Locality. 100 Parts of Dry Combustible contain : Carbon. Hydrogen. Oxygen. Ash. Canton Goneza . ■ 59.98 4-75 29.42 5.85 ANALYSIS OF COAL FROM TUSCANY, BY LA CAVA AND BUNSEN. Locality. 100 Parts of Dry Coal By whom analysed. Contain : neave : 1 s IS jS i i i Monte Massi (Tuscany) „ Bomboli . „ Massi 62.00 76.49 73-63 74.00 5.00 4.86 S-28 4.20 0.92 0-93 17 17 17-83 13.01 89 .00 14.25 4.71 3.20 4.10 56.5 th 57.6 60.7 to 61.3 La Cava Bunsea ANALYSES OF COALS. 765 ANALYSIS OF COAL FROM SILESIA AND WiSSTPHALIA, BY W. BAER. P. Percentage in Dry Fuel. | Locality. a i 4 s s ■s Sid's ^ ^ a ^« Silesia 1 — Leopold pit 3- 55 76.21 5-03 13-50 5-26 Fausta pit, Clara seam 3-75 76.63 4-9« 13.92 4.47 , , Fausta Beam . .3.«4 77.2s 4-5« 13-35 4.82 Koiiig's pit, Gerhard seam 4.15 79-51 4.87 12.96 2.66 ,, Heintzmann seam . 4-37 73-4« 4-95 18.64 2.93 Pit Morgenrcith 8-35 74-57 4.82 16.14 4-47 „ Leo 4.06 78.22 4.89 12.95 3-94 „ Louise, upper seam 3.«i 70.02 4-99 14- «7 IO.I2 lower „ 3-27 70.79 5- .32 19-34 4-55 „ Eugeniens Gliick 6.83 73.20 4-93 19. II 2.7b „ Gliickhilf .... 2-39 80.82 5.10 9-51 4-57 „ Konigiu Louise, Heinitz seam 3-35 73-91 4.85 17-59 3-65 Westphalia : — Zeche Laura .... 1.05 74.81 .4-35 8.76 12.08 „ Glucksburg, Franz seam . 1.28 72.66 4.05 9.24 14.05 „ „ Flottwell seam 1.08 77.25 4.02 8.14 10.59 „ der Engelsberg I-Z3 85.90 4.56 6- .33 3.21 „ Schafberg, Alexander seam 1.27 82.02 4.16 4-53 9.29 Tiefbau Franziska . 1. 19 77.10 4-55 11.79 6.56 „ Louise 2.25 78.05 5-oS 12.92 3-98 Zeche Prasident ■■31 79.72 4.62 12.40 3.26 „ Fiiedrich Wilhelm . 2.03 82.22 S.oo 7.71 5.07 Coke, Fausta seam . 4.96 87.82 1-43 5-H 5.61 „ Gerhard seam . 5.88 90.01 1.46 6.30 2.23 Peat charcoal .... 5.28 78.42 4.01 14-77 2.80 ANALYSIS OF COALS FROM THE MINES OF HERAOLEA — TURKEY. Locality or Name of Mine. Gaseoua Constituents. Ashes. PiMd Carbon. By whom analysed. Armoredjik . . . . 31.00 5.00 64. PC Rivot Zongoulaak 34.00 5.00 61.00 n Aladja-Aghry ... 45.00 4.00 51.00 ,, Silivria 49.50 7.00 43-50 Bichardson Eodosto, East of ... . 48.00 12.00 40.00 1^ „ West of 48.00 5.00 47.00 Erekli— Sea of Marmora .... 52.00 7-50 40.50 Amasrah 40.00 6.00 54.00 Rivot 37.60 10.40 52 00 Djattae-Aghazy 27.60 11.40 61.00 ^ear Heraclea . . ■ 30.00 7.40 62.60 11 ■ - • 31.00 7.80 61.20 Djaoucb-Aghazv . . 35-40 4.80 59.80 A adja-Aghazy . . . . 30.60 11.40 58.00 COMPOSITION OP COAL FROM DISCO ISLAND, ARCTIC REGIONS, BY DR. FYFE. Locality. Specifi.- Gravity. Coke. Volatile Matter. Carbon. Ash. Disco Island 1.3848 39-56 9.84 50.60 766 ANALYSES OF COALS. ANALYSES OF COAL (BRITISH) BY BAEK \.ND VAUX. icx) Parts of Dry Combustible \ CD .2 ■v; Locality. Contain : Leave : Water per cent, at no" C. in Saw jj § 13 t 1 & i ■ < t fuel. 1 »; z <» British : — Hawthoiu, Hartley, Newcastle (caking) .... 76.87 4-99 — 11.99 — 6.15 — 1.2 to 0.850 — ) Humrioks, Stockton 86.86 5.00 — 7-36 — 0.78 — 0.990 — Hawthorn, Hartley, Newcastle pq (caking) .... 9304 0.2b — 1. 61 — .■i-OQ — — — Newcastle caking . 81.41 .S.S.? 2.05 0-75 7.90; 2.07:66.70 I-35S 1.2760 \ Wigan cannel 80.07 SS.3 2.12 1.50 8.09 2.7060.36 0.906 i'.276o St. Helens, Lancashire, Eushy park 75.80 S-zi 1.92 0.90 II. 89 5.1765.00 3-232 1.2790 Staffordshire, Wolverhampton . 78-S75-29 1.84 0.39 12.88 10.3057.21 11.290 1.2785 M M — — — 2-57 — 3.01 58.20 8.390 1.2760 5 Anthracite, Wales . 90.393.28 0.83 0.91 2.97 1. 61 92.10 2.000 1-3925 > Lignite, Bovey, Heathfield, Chudley, near Exeter . 66-3''s-63. 0.56 2.36 22.86 2.27 .30.71 34.660 1. 1290 Turf 54.025.21 2.30 0.5628.17 9-73 2930 25.560 0.8495 Okegoh Teeritoky . — — — — — 35- 49,66.50 5.624 1.5780 COMPOSITION OF COAL- ASHES. 0) ■ 51 ti Wo Silica .... Alumina, insoluble in acids „ soluble in acids Lime .... Magnesia . _ . Oxide of magnesia . Oxide and sulphuret of iron Sulphuric acid Chlorine . Potash and soda 62) V 8 3 i5 45- S 43-9 3-2 3-3 1-4 1-7 0.1 0-3 Silica and alumina Oxide of iron . Lime Magnesia Sulphate of lime Potash . Moisture ^ 90.08 3-63 1.49 • trace 0-93 trace 3-80 100 1 99.4 99-93 COMPOSITION OF THE ASHES OF PEAT, BY BEETHIBR. Chateau Landon. Voitsumra. ^ Troyes. Vassay. Framont. Gelatinous silica 15.0 Silica 36.5 40 Alumina .... 7.0 17-3 and oxide iron 14 — 30 Carbonate and caustic lime . 63.0 Carbonate 51.5 Oxide of iron 7.0 33-0 ii-S Carbonate of potash . 0.5 Clay, insoluble in acid 7-5 — and silica 26 II. Zinc 2.0 23 — 30 Magnesia .... — 3-5 14 Sulphate of lime — 4-5 26.0 Muriate of lime . — 0.5 Carbonic acid Carbon .... — 2.7 and sulphur 23 1 00.0 lOO.O 100 lOO.O 100 ANALYSES OF COALS. 767 COMPOSITION OP THK ASHES OF DIFFERENT VARIETIES OP COKE, BT GAULTIER. Locality. ■3 fa « •i li SS, S2 M 3 s CO ■s( 1 a^ u. Ehglish : — Iron bridge .... 12. SS 42.10 34-40 4.80 0.40 ^.28 trace Dudley 8.64 35-4° 30.40 6.48 — 18.68 » Merthjr Tydvil .... 4-56 41.60 35-44 6.46 1.08 10.80 » St. Etienne : — Puits St. Henri .... 2.40 73.20 14.40 0.80 0.70 7.98 » „ du file ... . 2.40 54-90 37.00 3.20 — 2.30 ii „ de Carrode 4.90 56.50 23.00 0.40 0.76 14.38 17 „ Robert menu 5.60 44-5° 34-34 7.00 0.50 7.18 ij „ dessus .... 2.20 50.00 32.00 1.40 0.70 13.28 »t „ des planches 3-6o 43-50 36.20 6.20 0.50 9.42 )} „ de la grande fendue . 3' 50 58.20 34.00 0.30 0.30 3-32 IT RiVE-DE-GlEE : — Puits de la grande Croix 3.20 55-00 19.80 8.80 — 13.00 „ des Combes 8.70 36-30 11.00 24.20 — 19.06 i, de St. Matbieu . 4.90 55.00 22.24 5-50 8.80 3-32 )) ANALYSES OF BROWN COAL OR LIGNITE FROM PRUSSIAN SAXONY, BY F. BISCHOFF. LocaUty. Freshly Mixed Coaljielded: Percentage in Dry Fuel: ^1 . a > § i •a u 4: ^ a as g as , ^ Pi mo u «■ a« Riestedt, George Pit 33-4° 1. 197 57-13 4.16 27.05 11.66 ., „ fossil wood . 31-70 1. 218 61.13 5.09 31-95 1.83 Voigtstedt, earthy, with fossil wood 49.20 1. 241 49-15 4-45 32-25 14-15 Loderburg „ 49.50 1. 219 45-30 4-90 31-95 7-85 Mertendorf „ 48.60 1233 49-45 5-17 24-84 21.54 Altenweddingen, earthy .... 47-30 1. 194 57-71 4-75 22.94 14.60 Biere 46.90 1.200 55-92 4-77 22.48 16.83 ToUwitz, earthy 49.60 1-257 57-51 529 25.40 11.80 Pretzsch „ . . . . 50.70 1. 213 .50.80 4.96 26.20 18.04 Teuditz „ 48.60 1.263 54.02 5.28 27.90 12.80 Brumby „ . . ... 40.60 1.263 47.78 4.28 18.42 29.52 Lebendorf „ 42.70 1. 318 47-73 4-34 17.64 30.29 Zscherben „ . ... 49.50 1.207 57-82 S-59 24-53 12.06 Runthal, upper seam, earth v . 50.00 I- 139 59-35 5-86 26.31 8.48 „ lower „ „ ... 48.70 1. 127 65.94 6.07 25.67 2.32 Wiirschen, earthy .... 49.90 1. 142 60.76 5-99 23-13 10.12 Gorstewitz „ .... — 67.11 10.28 10.02 12-59 Eauen (Forderkohle) 14-83 59.00 4-55 25-77 10.68 ANALYSES OF AUSTRIAN LIGNITE, BY SCHROTTER. » Locality. 100 Parts of Dry Combustible 1 ■3 1 Contain : Leave : J 1m ■s. 4.26 3-84 4-49 4.29 i 1 CO 1 3 4 -5 Wildshut Thallern Glognitz ....... Pitch coal from Gruubach 53-79 49.58 57-71 69.66 0.98 4.56 3-12 1.71 25-39 22.68 22.14 17.42 15-58 19-34 12.54 6.92 54.7 63-7 54-4 60.9 1.306 ■•413 1.364 1-320 768 ANALYSES OP COALS. ANALYSES OP GERMAN BROWN COAL OB LIGNITE, BY W. BAER. loo Parts of Combustible dried at • 212° F. yielded : Water per L-ent. Localitr- g Si in Raw Combus- a s ■g. a II < tibles. Eauen, in pieces (i) 61.38 4.91 23-57 10.14 38.66 (2) . , 60.00 4-56 25-43 10.01 25.82 Fraiilcfurt on-tlie-Oder 59-65 4.86 26.41 9.08 16.07 Tollwitz (i) 63.14 5-17 19.99 :i.io 51.46 .. (2} • ■ 64.70 5-63 18. 1 1 11.56 39.52 .. (3) . • 62.07 S-Sb 19.90 12.47 18.03 Zscnerbeii 64.26 .■;-76 17-44 12.54 45-37 Biere 52.80 4-99 15-67 26.54 31.24 Steohali . 64-53 5-17 25-35 4-95 43-67 Wittenberge 64.07 5.03 27-55 3-35, 17.26 ANALYSES OF LIGNITE, CHIEFLY Of FRANCE, BY BERTHIER AND DUFBl^NOY. Locality. Lignite du Val Pineau „ Gurdanne „ Fureaii . ,, Saint Martin de Vaud ,, Koep Fuarch . ,, Elbogen . ,, Alphie ,, 'J'riphilis . ,, Konnin . ,, Baffin's Bay . Bituminous wood ^ )) »» . • Lignite Utweiller (Rhine) Germany Edon (Charente) . St. Lon (Basses-Pyr6n§es) L'Enfant-dort (Bouches-da-Eh6ne) Minerve (Aude) Dauphin (Basses-Alpes) Jet Ste. Colombe . Lignite Marseilles . „ DnuphinS . Fossil wood .... Bituminous wood Cologne earth .... joo Parts of Combustible contain : Carbon. 36.5 41.8 36.0 45-0 41.0 24.0 27.5 31.0 34-0 58.8 44-1 37-1 67-3 42.9 39-0 48.4 49-3 32.6 43-6 60.4 49-3 43-6 44.1 384 37-4 Volatile Matter. .57-0 43-0 S3-0 44.0 47.0 69-3 56-5 51.0 53-5 i 29-3 1 16.7 137-1 ( 17-4 61.5 31.8 52.5 50.0 46.0 46.8 57-4 49.0 liqnid gaseous liquid gaseous ■J Ash. 9 8 o I liquid 4 gaseous 3 liqnid 8 gaseous 3 liqnid 6 gaseous .6-5 15.2 II. o II. o 12.0 6-7 16.0 18.0 12.5 5.2 1.4 1-4 0.9 •4.6 II. o 5-6 3-9 10. o 7-4 1-7 3-9 7-4 1-4 2-5 5-7 By whom Berlhier , Dufr6noy ANALYSES OF TURF FROM KAISERLAUTERN, NEAR HOMBERG, BY WALZ. Locality. 100 Parts of Combustible dried at 212° P. yielded : Water per cent, in Natural Conditicn. Carbon. Hydro- gen. Nitro- gen. Oxygen. Ash. Mackobacher Moor . ^ . Steinwender .... Neidermoor .... 62.15 57.50 47.90 6.29 6.90 5.80 1.66 I-7S - 27.20 31.81 42.80 2.70 2.04 3-5° 8.0 8.3 ■ 8.0 ■ ■ y ANALYSES OP TURF. 769 ANALYSES OF TURF FROM GERMANY, BY JAECKEL Locality. Undried Turf gave: 100 Parts of Dry Turf, Ash deducted, yielded : Ash. Water. Carbon. Hydrogen. Nitrogen and Oxygen. Havel Flat, near Berlin (l) :: :: It Linnum Moor Friesack Moor Cassel . Near Hamburg 8.13 S-33 5-5' 8.36 8.91 18.27 1.89 17.63 19.32 18.89 31.34 21.82 26.60 18.83 56.43 53-51 53-31 59-43 57.12 532 5.90 5-31 5.26 S-32 38.25 40.59 41-38 35-31 37-56 ANALYSES OP TUKF (CHIEFLT FRENCH), BY BERTHIER, DIDAY, AND SAUVAGES. Locality. Carbon. Volatile Matters. Ash. Water. By whom analysed. Liquid. Gas. Demarary Chateau- Landon Clermont (Oise) Reims Voitsuma (Bavaria) . Rue (Somme) . New Abbeville (Somme) . Velleron (Vaucleuse) Sfioheval (arrondissement Rocroy and Neziferes) 23-5 26.0 30.1 34.7 38.6 21.0 23.0 17-3 22.0 36-7 31.0 28.4 39.9 38.5 72 72 65 39 22.5 28.0 24.1 18.6 21.2 2 3 2 17.3 15.0 17.4 6.8 1-7 7.0 4-8 17.4 8.3 0.5 I Bertbiui- Diday Sauvages ANALYSIS OP FUEL PROM RUSSIA, BY VOSKRESSENSKY. Variety of Fuel. Locality. § 5 1 s 1.732 '11 4 •3 Anthracite Gruschewskaja Stanitza (Don Cossacks) . 93.785 2.940 1-543 Lissitsclija Balka . 90.598 2.840 1. 712 4.850 Coal . Solikamsk (Govt. Perm) 72.228 4-275 17-457 6.040 Bachmut .... 71.173 4-977 21.502 ' 2.348 Charkow (near Petrowska Sloboda) . 72.249. 3-524 21.067 3.160 „ Tschernolesnaja (Cancfisi-.in) 70.724 4-8';5 21.705 2.716 ,, Kaluga (near Selinina) . Wladimir (on tbe Oka) 63-934 4.210 12.456 19-380 60.262 4-430 28.848 6.460 Bjasan (on the Ranona) 50.259 4.510 19.271 25.960 Brown coal fiflis .... 63.346 5-678 27.836 3.040 Irkutsk (on the Argiini.i) 47.462 4.560 33-028 14.950 Bit. shale . Kurland (on the, Windau) 20.600 2.750 19-730 56.920 Turf St. Petersburg 39.084 3-788 51.088 6.040 3» APPENDIX. ON THE GENERAL PBINCIPLES OP COAL WASHING/ By Me. FREDEEIC'K J. EOWAN, C.E. Coal washing forms an increasingly important step in the preparation of the smaller varieties of coal for the market. For the manufacture of coke, where the coal is usually first reduced to powder, it is even more important. Careful classification of the different kinds of small coal according to size receives great attention on the continent of Europe, but is generally neglected in this country by the majority of mine-owners, as was the case in France until recently, according to M. Callon's remarks in his " Lectures on Mining."* Where it is practised, however, it is found to be of great advantage, because there is a certain size or condition of coal which is the most suitable for different processes or operations, and sizing therefore enables the coal to be applied more easily and in the most suitable con- dition. In some parts of the Continent a higher price has been obtained for coal thus classified according to a suitable size than was previously paid for the same coal in a mixed state, having an average of larger pieces than was necessary for the purpose of the consumer. The large coal was thus set free for other purposes more suited to it. Hand-picking is generally resorted to in this country, and shaking or revolving screens are sparingly used in general. Thei-e is no doubt, however, that much of the hand labour could be replaced by mechanical methods which classify the coal more completely, at the same time treating it more gently, so that a smaller proportion of small coal and a less cost for sorting and handling result. Washing machines are themselves classifiers according to size, besides being purifiers of coal from pyrites, shale, and earthy matters in general. Their use, with that of the other mechanical appliances for handling and sizing the coal, is regulated simply by the question of cost. Comparing the treatment of ores and coal as regards the quantity and value of the products, M. Callon remarks:! "In the case of metallic ores we have to operate upon small quantities of valuable substances, which admit of our having recourse to delicate contrivances and frequent repe- titions of the same process, notwithstanding the amount of capital required and the high cost of labour entailed by it. In the case of coal, on the con- trary, we are dealing with enormous masses of a substance of comparatively little value, the profit upon which is reduced to a minimum by competition. » Deliverer! at the Ecole des Mines, Paris ; translated by C. Le Neve Foster and W. Gal- loway (London, 1886). t " Lectures on Mining," p. 144. 3 D 2 772 APPENDIX. We are consequently forced to employ special machines, as simple as possible, acting automatically, as far as practicable, and capable of treating con- siderable quantities. We must generally abandon all idea of treating coal by frequent repetitions of the same process, or, at all events, do so sparingly, so as not to burden it with too heavy costs. And, finally, in planning the whole arrangement and the means of transport, we must have recourse to the best mechanical contrivances, so as to carry out the operations both with simplicity and economy." It is not by any means a simple matter to select the best machinery for the treatment of a particular coal, because of the many varieties in the nature of coal and in the minerals mixed or associated with it, the differ- ences in the manner and degree in which the foreign matters are mixed with it, the manner in which the coal breaks up, and all circumstances tending to produce varieties in the yield of ash in the large and small coal. Variations in washing machines, moreover, are needed according to the different sizes which it may be desired to treat in them ; and the question of the amount of loss by the formation of mud or sludge has an important bearing on the means of treatment that are employed. These are all matters which demand experience in the treatment of different varieties of coal in order to their being properly dealt with, so that the interests of neither coal-master nor consumer shall be neglected, and it may safely be said that no general rule of treatment can be laid down, and no one form or arrangement of machines can be prescribed as suitable for aU cases. The process of coal washing, whatever may be the special machine employed, depends upon simple but -very interesting principles, namely, the conditions which accompany or regulate the fall of solid matter in deep or shallow water. It has been found that particles of different substances fall in a fluid at different speeds according to their densities and volumes or sizes. M. Gallon* takes the case of a fluid, of a given density, at rest, in which a particle, having a certain specific gravity and section at right angles to the line of fall, is falling with a given velocity, and shows that three forces act upon the particle. These are, i, gravity; 2, the thrust of the fluid ; and 3, th& resistance due to the viscosity of the fluid, which resistance is proportional to the surface of the body as well as to the square of the velocity. H& examined the action algebraically and worked out the different effects due to shallow and deep fluids, arriving at the result that in a shallow fluid, or, in other words, at the very beginning of the fall, before there has been time for the velocity to become great, the motion takes place solely according to density. Consequently, "those machines which utilize only the first instants of the fall, will have a high effect as concentrators." When the depth is sufficient for a regular state of affairs to become established, all particles having a like volume and specific gravity will have an equivalent rate of fall. P. Von Rittingerf investigated the subject many years ago by means of numerous experiments, and found that in water the limiting velocities of particles of different diameters and different densities (that is, the velocities of descent in still water which they do not exceed, but which become uniform for each piece respectively, when space permits them to acquire those speeds) are quickly reached, small pieces of i millimetre diameter reaching it in under half a second, and large pieces of 16 milli- metres diameter in less than one second. The following table gives some of Rittinger's results which illustrate this point : — * Op. cit., p 47. t Lehrbuch der Aufbereitungnhunde (Berlin, 1867). APPENDIX. '73 Nature of the Substance. St- 11 ceo Values ofthe Velocity in iSec. J Sec. J Sec. I Sec. 2 Sec. Galena Pyrites . Quartz . 7-S 2.6 millira." i6 i6 i6 metre. 0.903 0.825 0.570 metre. 1.444 1. 174 0.767 metre. 1.630 1.287 0.801 metre. 1.650 1.293 0.817 metre. 1.650 1-293 0.817 Galena . Pyrites . Quartz .... 7-S S-o 2.6 4 4 4 0.704 0.586 0.383 0.814 0.643 0409 0.823 0.646 0.409 0.824 0.646 0.409 0.824 0.646 0.409 Galena Pyrites . Quartz . 7-5 S-o 2.6 I I I 0.409 0.321 0.203 0.413 0.323 0.204 0.414 0.323 0.204 0.414 0.323 0.204 0.414 0.323 0. 204 j From many experiments with different minerals, and from calculations, Rittinger deduced a general law for the velocity of any substance falling in still water. This he expressed by the formula :* — Velocity in feet per second = 1.28 i^D (d— i), where D = the diameter in inches of the holes in the riddle through which the substance has passed. d = the density of the substance, or its specific gravity compared with water taken as unitj'. 1.28 is a constant which was gradually arrived at from experimental results (where the velocity is expressed in metres per second, and D is taken in metres, this constant is 2.44). This general principle having been established for the case of substances falling through still water, it is found that it is applicable also to the varied conditions of an ascending regular current of water, a descending current, or a horizontal current. If particles are subjected to the action of an ascending current, either the speed of the current may be equal to the limiting velocity of fall in still water — in which case the particles will remain stationary — or if the speed of the current be either greater or less than this, the particles wUl either rise or fall with a velocity due to the difference of speed. In a horizontal current, the particles will take a curved path, the shape of the curve depending upon the speed of the current and the density of the particles. A very interesting diagram, showing graphically the trajectory of a particle of a mineral in relation to the trajectory of a particle of the water in a current, was communicated by M. Marsaut in the discussion on Mr. Harvey's paper on " Coal Washing " (in " Min. Proc. Inst. O.E.," vol. Ixx., session 1881-82, part iv.), and may be taken as affording a useful graphic representation of these principles. Figure 607 shows this diagram, regarding which M. Marsaut observed that " in effect, if the molecule of water and the particle first in contact left their trace on the drum of General Morin's weU-known machine, the trajectory of the water would be a curve similar to AB, more or less approaching a sinusoid. The point A, where the screen had been shown, was that where the water had just the velocity limit of the particle in water and where consequently the water began to raise it. The particle rose in proportion to the velocity of the water, then stopped and retrograded as that velocity diminished. Hence it was evident that during the whole • "Engmeering," vol. xxiit. p. 4. 774 APPENDIX. evolution the particle of coal had continuously descended with respect to the particle of water, developing ordinates comprised between the two curves, such as ah, representing the path traversed." Fig. 607. It is evident that air may be taken as the fluid, instead of water, and, allowing for the difference in density and viscosity, we may apply the same general principles to the separation of mineral substances by means of currents of air. The use of air has been carried out in pneumatic classifiers in America and in the air- jig of M. Krom, mentioned by M. Gallon ; but it is evident that it is suitable only for materials in a fine state of division — such as sand or finely ground ores — and that the currents of air must have a com- paratively high velocity. A mixture of air and water introduces a modified state of aflFairs not easy to follow unless the condition of the mixture and its average density were known. If the water be broken up into a frothy state by the air, it is evident that the mixture will act as a fiuid of less density than water but greater than air, and wiU not have the same efiect upon large as upon small particles except at a higher speed of movement than water requires. If, however, the water remains sufficiently solid to allow the eifect of its density to be felt by the mineral particles, then the air must act either in imparting a greater speed to the water, or in producing irregular pulsations in the movement of the particles of the minerals, according as they are immersed in water or in bubbles of air. Comparative practice will no doubt determine whether these effects are advantageous or not. Experiments have been made by Dr. T. M. Brown* with a method of separating coal from its impurities by means of the employment of a liquid of greater specific gravity than coal but less than of slate, &c., associated with it. This liquid would have a greater density than water, and would allow all coal to float while the impurities alone sank : and this result would be arrived at without motion of the liquid being necessary. A liquid suffi- ciently cheap and readily obtainable was found in the solution of calcium chloride in water, and the results of experiments on a small sc&,le were thoroughly satisfactory. These experiments illustrate effects of an opposite character to those produced bj' the use of air in coal washers, and they have a special interest on this account. Before leaving this rapid sketch of general principles we may remark that Rittinger's fundamental law has shown the way to rules which should regulate the separation of coal by riddling, where this operation precedes * " Trans. Amer. Inst. Min. Eng.," Philadelphia Meeting ; "Jour. Iron and Steel Inst.," vol. ii. 1884, p. 700. APPENDIX. 7>5 the " sorting by equivalence'' of the operation of washing. M. Callon* has given the theoretical expression of these rules, and the application of Kittinger's method, which we quote, is taken from the digest of M. Marsaut's paper,! published in " Engineering." The determination of the limits of size within which preliminary riddling should he performed depends upon the density and consequent degree of impurity which may be taken as hmiting the commercial value of the washed product. The following table gives approximately the densities of pure coal and of the foreign substances associated with it, and the limiting velocities of pieces of different sizes as deduced from Rittinger's formula — 2.44 J'D{d-i). Materials ia Pieces of Irregular Shape;!. Density.' Limit npr Velocity of Fall in 1 letres d. (d-i). per Second. Coal, pure „ shaly „ more slialy . Shale, pure . „ with pyrites Pyrites . 1-3 1.6 1-9 2.2 3-4 50 0.6 0.9 1.2 2.4 4.0 0.267 0.578 0.463 0-S35 0.756 0.976 0.231 0.327 0.400 0.463 0.654 0.844 0.189 0.267 0.327 0.378 0-535 0.69 J 0.134 0.189 0.231 0.267 0.378 0.488 Diameter of Holes J-Millimetres in Eiddle ( Say inches 40 4 30 20 f 10 3 a 1 The first column of density is the absolute density d, taking water = the excess (d — 1) above that of water. 10; the second is "When coal becomes fo sh^ly that its density rises to 1.6, it can scarcely be considered any lonjjer capable of being used as fuel. If this, therefore, be assumed as the limit of density or impurity to be allowed in the washed pi'oduct, it is evident that before washing the stuff which has passed through a mesh of 46 mm. (i^ inch), it should first be riddled again over a mesh of 20 mm. (I inch) to separate all ' below this latter size. For it is seen from the above table that the 20 mm. shaly coal of 1.6 density falls through the water with the same velocity (0.267) as the 40 mm. pure coal of 1.3 density • consequently the 20 mm. shaly coal, together with all smaller stuff of great density, would fail to be separated from the 40 mm. pure coal by the washing." Similarly on this assumption with regard to density, any class of raw coal which had passed through one riddle should be riddled again oyer a sieve of half the previous mesh, thus ; — mm. From btuff which lias already passed through a mesh of . . . 40 Should be separated all that passes through a mesh of . . . 20 If, however, we wish to remove from the washed product merely the pure shale, having usually a density of 2.2, and all substances of greater density a ratio of 4 to i for the preliminary riddlings would serve instead of the foregoing 2 to i. Then — , . , , , , , "•!"• mm. mm. mm. mm. From stnfi which has already passed through a mesh of . . . 40 30 20 10 5 Should be separated all that passes through a mesh of . . . 10 7J 5 2i ij Other data may be assumed, but these examples will serve to show how • Op. cit., pp. 51, 52. t Bulletin de la Soc. de VIndm. Minirale, 1879 ; " Min. Pron. Inst., C.E.," vol. Iv. p. 2c,a. mm. mm. mm. mm. 30 20 10 5 15 10 5 24 77^ APPENDIX. the preliminary riddling may be arranged to secure a given result in the washed product. " If a lot of unriddled small coal, such say as would pass through a mesh having holes of 40 mm. {i\ inch) in diameter, were allowed to fall through a sufficient depth of water in any vessel, or were exposed long enough to the action of an ascending current of water, there would be formed in the vessel a series of horizontal layers, each composed of bits which had fallen through the water with the same velocity, and must necessarily be deposited at the same depth. Each thin layer thus deposited, with the exception only of the bottom one, would be made up of large bits of coal having the minimum dens-ity, of successively smaller pieces of less pure coal of greater density, and of shale and other impurities ; the bits thus assorted being all of them equal in speed of . falling, or equivalent to one another throughout each individual layer." Several classes of stuff thus sorted in water by the simultaneous agency of size and density, present a different result from that produced by classification effected according to size alone by ordinary riddles ; and it is evident that each class of stuff thus forming a layer could have the pure coal separated from the foreign matters in the layer by being riddled through a suitable mesh. The riddling is, however, usually done first, because it is found that the washing is more perfectly carried out when the coal is sized before washing, so that each size can be washed separately. This is easily understood from the foregoing principles, and may be explained by considering the action of washing machines, as is done by Mr. R. de Soldenhoff,* and by the fact that obviously a mixture of pieces of coal, shale, ses of coal by, 764 Absolute heating effect, calculated by Welter's law, 336-338 fonnulje lor, 358, 359 Absorption of water and gases by charcoal, 108, 109 by coke, 143 Account of the introduction of hot blast by Neilson, 452 Action of coal anj coke in the blast furnace, 244i 245 . of flame in furnaces, 682, 683 of the Yaryan apparatus, 593 Actions proceeding In the blast furnace, 638 Adams' gas-cooking stoves, 429, 430 sas-stoves, 417, 418 Addie's process for ammonia recovery, 277, 278 Advantages of flues for heating boilers, 505 of the Yaryau apparatus, 594 Af Ulir's observations on the drying of wood, 94 statements of yield from meilers in Sweden, 105 Agricultural Society's trials of portable engine 'boilers, 729 Agriculture, use of fuel for steam power extend- ing in, I Air, effects of, on different kinds of coke, ig8 heated, use of, in gas furnaces, 667 of dwellings, expenditure of heat in warm- ing, 377 vitiation of, by respiration, &c., 493 volume of, calculated from waste gases, 718, 719 required for combustion by different fuels, 361, 362 , Air-dried wood, how prepared, 4 Aitken's (Henry) coke ovens for recovery of bye- products, 182, 183 method of calcining black-band ore, 637 Alexander and McCosh's process for ammonia recover)', 277 Alfreton, Bunseo and Flayfair's analyses of gases from, 237 Allen's (AlfVed H.) analysis of astatki and blast- furnace oil, 318 Amagat's pyrometer, 343 America, extent of oil production in, 293 American and British experiments with coals, anthracites, analyses of ash of, 58 coal and coke, analyses of, used by Dewey, I53-TS9 coal.-*, analyses of, 749-760 coala, average produce of coke iVom, 141 American coals, character and efficiency of, 696; 697 coals, tested in landboiler at Washington, 727 coke, results of examinations of, 153-160 cokes, physical properties of, by Fulttm, 199 experiments on charcoal burning, 106 American oil compared with Russian, 299 stoves, 407, 40B trials, coaJs used in, 713, 714 of coals, results of, 712 of gas firing for boilers, 566-575 ' Ammonia and tar from blast furnace gases, 232 from producer gases, recovery of, 275-278 and tar recovery in coking, 178-192 from blast furnace gases, 248 tar, charcoal, tfcc, obtained from peat dis- tillation, 206-208 Amount of ash in wood, 8 Amounts of coke and bye-products from Aitken ovens, 183 from Jamieson ovens, 185 from Otto ovens, 192 from Pernolet ovens, 181 from Simon-Carves ovens, 186 Amount of regenerator surface required, 669 ' of water in wood at different periods, 3 Analyses of American coal and coke ust-d in Dewey's investigations, 153-159 of American coals, 749-760 of anthracite, 57 of South Wales, 737, 738 of anthracites of Europe, 742 of ash of anthracites, 58 of brown coal by Varrentrapp, 26 of coal, 52 of peat, 15 of Austrian lignite, 767 of bituminous eoaU of Asia, 749 of bituminous coals of England and Scot- land, 733 of bituminous coala of France, 743-746 of bituminous coals of Midlands and N. Wales, 739. 740 of bituminous coals of Yorkshire and Scot- land, 740-742 of bituminous and semi-bituminous coals of S. Wales, 734-737 of British coals, 766 of brown coal, 26. 27 of cannel coal, 47, 48 of coal, 53-56 from Hungary, 762 from Silesia and Westphalia, 76 from Turkey, 765 from Tuscany, 764 from Zwickau, 761 78o INDEX. Analyses of coke, 143 of coke made by different methods, by Bell, 193 of combustibles from Europe, 747, 748 of composition of wood asliea, 9 of dried wood;* and brushwood, 10 of fire-damp, 61 of French lignite, 768 ' of fuel from Russia, 769 of gases from Askam and Marchiennes, 248, 249 from coke ovens, 201 occluded in coal, 84, 85 of German coals, 763, 764 of German lignite, 768 of lignite from Prussian Saxony, 767 of natural gas, by S. A. Ford, 290 of New South Wales coals, 761 of New Zealand coals, 760, 761 of peat, by Regnault and Mulder, 19 by Ronalds, Voskressensky, and Kane and Sullivan, 20 of producer gas, 278-285 of Ru-^sian and American oils, 299 of turf from France, 769 irom Germany, 768, 769 Analysis of ash of brown coal by Relnsch, 25, 26. of astdtki from Baku, 318 of blast furnace oil from Coatbridge, 318 of Bramwell's results by W. Anderson, 731, 732 of codl from Disco Island, 765 from Sardinia, 764 from Saxony, 763 of natural gas, by Dr. G. Ilay, 290 of steam boiler performance, 496, 497 Anderson's (W.) application of Carnot's law to boilers, 496 comparative value of coal, wood, and peat for eva^poration, 21 examination of Bramwell's results, 731, 732 experiments with flame in boiler tubes, 577 on heat emission of hot-water pipes, 481-484 Andrews (G. W.), analyses of coal by, 753 Angsirom's foi-mula for heat transmission, 495 Annealing furnace, gas, 691 Annual production of coal, 45 Ansell's fire-damp indicator, 74 Anthracite, analyses of, 57 general description of, 57 nitrogen in, 57 Anthracites of Europe, analysis of, 742 of South Wales, analyses of, 737, 738 relative value for heating, 363 Antiseptic qualities of peat, 11 Apparatus for classifying coal, 776, jjj for distillation of wood for vinegar, Ac, 607, 608 Application of gas for heating, 399 400 Applications of the Yaryan apparatus, 593 Appoit coke ovens, 174-176 Archer's method of using liquid fuel, 302 Art-a of tire grate in relation to heating surface, 504 of peat in Britain and Ireland, 12 Areas of coal land in different countries, 44 Arnott's improved fire-place, 394-396 ■ stove, 405, 406 ventilating valve, 408 Arrangements of gas-iired boilers to different plans, 539-582 Artemeff's apparatus for liquid fuel, 307 Artificial fuel, 208-226 Ashburner's (C. A.) accounts of the Tennsylvania gas district, 2S8, 289 Ash, amourit of, in brown coal, 24, 25 diminishes value of fuel, 2 in American compared with British coal, 51 in charbon roux, 1 1 1 in coal, 49-51 in peat charcoal, 116 in wood, estimates by Berthier, Karsten, Chevandier and Bottinger, 9 of American anthracites, analyses of, 58 ■of brown coal, analyses of, by Reinsch, 25, 26 of canncl coals and shales, compared, 48 of cannels, special features, 49 of charcoal, 109 of coal, general character of, 51 of peat, analyses of, 15 of wood, general character, 8 variation in quantity of, in different coals, 32 weight of, in a cubic foot of peat, 19 Ashes, coal, composition of, 766 of different varieties oJE coke, composition of, 767 of peat, composition of, -^66 Asia, analysis of bituminous coals of, 749 Askham, gases from, analyses of, 248 Astatki from Baku^ analysis of, 318 Atmospheric pressure, influence of, on fire- damp, 66 on the luminosity of flame, 372 Aidd's mechanical stoker, 533, 534 Austrian lignite, analyses of, 767 Average composition of red chnrcoal, 112 produce of coke from British coals, 141 values of coals from different localities, 701 Aydon's apparatus for liquid fuel, 303-305 B Baer (WO, analyses by, 763-768 Bailey, analyses of coal by. 754 Bainbridge's observations on moi-iture in peat, 14 tests of calorific power of peat, 21 Baking oven, 624 Baku astatki, analysis of, 318 Balance-sheet of results of boiler trials, 730 Bald (Robert) and Buddie (J.) on coal dust, 75 Balling, analysis of coal by, 748 Barclay's (A., & Son) coal- washing machine, 131, 132 Barrow-in-Furness plan of collecting gases, 232 Barum, Scheerer and liangberg's analyses of gases from, 234 Baudin, analyses of coal by, 743-747 Bavarian malt kiln, 623 Beaufumd's gas-fired boilers, 539, 540 gas producer, 253 Bfeche (Sir H. dola) and Playfair's examinations of coals, 702 Bee-hive coke oven:", 166-170, 180-185 Beilby's analyses of producer gas, 284 Belgian coke ovens, 167-200 Bell's (Sir I. Lowthian) distribution of heat in blast furnaces, 641 examination of different cokes, 193-196 of furnace gases, 237-248 researches on hot blast, 470-477 Benson's gas producer, 255 Btrard's coal-washing machine, 129 gas producer, 254 Bertrhelot's corrections of Bunsen'ei flame tem- peratures, 368 demonstration of smoke formation, 718 INDEX. 781 Berthelot's pyrometer, 346 Btrthier, analyses by, 733-769 Berthier's estimations of ash in wood, 9 litharge process founded on Welter's theory, 337 Uerzelius, estimate of water absorbed by char- coal, 108 Beschoren's results of yield from meilers, 105 Bessemer's furnaces for combustion under pres- sure, 388 patent fuel process, 216-224 Bethke and Ltirmann's defence of Welter's theory, 356-358 Bicheroux furnace, 685 Hischoff (F.), analysis of coal by, 767 Bischofs gas producer, 250 Bissetl's hot-air stove, 450 Bituminous coals of Asia, analyses of, 749 coals of France, analyses of, 743-746 coals of Midlands and N. Wales, analyses of, 739. 740 coaU of Yorkshire and Scotland, analyses of, 740-742 Blake, analyses of coal by, 758 Blair, Campbell and McLean's arrangement of Coffey's still, 602-604 Blast furnace, actions proceeding in, 638 Cleveland, 639, 640 compared with open fire as to combustion, 473 distribution of heat in, 641 forms and dimensions of, 638, 639 index of working found in the gases, 641 influence of size on working, 641, 642 method of working, 639, 640 Scotch, 638 section on, 637-642 Staffordshire, 638 tar, Watson Smith's results, 203 value of coke, 192-199 waste gas, 227 West Cumberland, 640 Blast furnaces, nature of combustion taking place in* 473 use of lignite in, 28 Blast pipes in locomotives, effects and propor- tions of, 511 mavier's account of the peat marsh of Montoire, 12 Bleacher's goods, method of drying, 621 Blowers of fire-damp, 62-68 steam, fan and under grate, for fires, 383, 384 Blown-out shot, effect of a, on escape of fire- damp, 67 Blowpipe gas furnaces, early, used in Sweden, 670- 674 gas furnace for puddlinfr, 674-676 gas furnaces, Sutherland's, 674 gas furnace at Treveray, 674 Hoilmer's screw grate, 516-519 Boetius* furnace, 684 Hog-butter, examination of, by Brazier, 62 Boiler, steam, analyses of work obtained from, 488 at St. KoUox with double furnace, external, 514 combustion temperatures of, 499 Cornish, 506 , firing by gas, regenerators for, 692 performances and proportions, D. K. Clark's examinations, 723, 726 tubes, length of, to prevent extinguishing flame, 577 Boilers, advantages of flues for heating, 505 Boilers, amount of evaporation economically obtained, 537 application of Carnot's principle to, 496 British and American experiments with, comparative trials of, by Industrial Society of Mulhouse, 721, 722 effect of coal under, 702 egg-ended with gas-tiring arrangement. 575, 576 extent of grate surface, 503, 504 gas-fired, 535-582 gasrfired, at D. Rowan & Son's, 575 582 gaa-flred, Beaufume's arrangement, 539, 5 1.0 gas-fired, by natural gas, 575 gas-fired, Cornish boiler, 545, 546 gas-fired, different plans, 575-579 gas-fired, Dixon and Gadsden's trials, 566- 575 gas-tired, double-fiued boilers, 562 gas-fired, French or elephant boiler, 544, 545 gad-fired, Fichet's arrangements, 543-550 gas-fired, Hartmann's arrangement, 551 gas-fired, Haupt's arrangements, 551-556 gas-fired, Minary's arrangement, 542 gas-fired, single-fiued boilers, 563 gas-fired, used in Darby's trials, 556, 557 gas-fired, vertical boiler, 546 gas-fired, with waste gas from furnaces, 538, 589 heights of combustion chambers for different fuels, 505 land, evaporative results with, 724, 725 locomotive, 507 marine, 508, 509 evaporative results with, 727, 728 portable engine, evaporative results with, 729 rates of combustion in various kinds, 504 rate of transmission of heat in, 502 transfer of heat through plates, 501 using Hindley Yard coal, evaporative results with, 724, 725 velocity of hot gases from, 503 Boiling-points of various substances, 120. 121 point of water altered by vacuum, 590 Bois, analyses of coal by, 746 Boistel's analyses of Siemens' producer gas, 280 Bond's (Dr.) euthermic gas stoves, 420, 421 Booth (J. C), analyses of coal by, 757, 760 Bottinger's analyses of compobition of wood ash, 9 Boulier Brothers' pyrometer, 343 Boussingault, analyses of coal by, 760 Boutigny's boiler, 581, 583 Boy^, analyses of coal by, 746, 747, 760 Bramali's application of regenerators to cupolas, 647 Bramwell and Russell's *' Balance Sheet," 730 Bramwell (Sir F.) and RusscU's record of evaporative results, 729, 730 Bramwell's results, examination of by W. Anderson, 731, 732 ' Brazier's examination of bog-butter, 12 Breeze ovens, Davis' and Siemens', 176- 180 Brick (fire) burning, kiln for, 627 (red) burning, kiln for, 629, 630 stoves, Continental, 410 stoves, Dunnachie's, 412, 413 Brine, evaporation of by gas, 587 evaporation of in open pans, 5S5 Briquette manufacture at Blanzy, 214, 215 in Britain and on the Continent, 225, 226 Britain, area of peat in, 12 782 INDEX. Britain, inveBtigatious on fire-damp and coal- dust, 70-80 wealtl) of, dependent on store of fuel, i British and American experiments with boilers, 723 with coals, 705 British coals, an«lyses of, 766 average production of coke from, 141 British Museum, heating arrangements of, 486, 487 Brown coal, analyses of, 26, 27 ash of, 24, 25 ash of, analysed, 25, 26 nitrogen in, 26 relative value for beating, 362 used in gas producers, blast furnaces, loeo- motiveti, Ac, 27, 28 water in, 24 weight of a cubic foot and specific gravity of, 27 Brown coal or lignite from Saxony, analyses of, 767 German, analyses of, 768 use of in iron manufaciure, 27' varieties of, 24 {see also Lignite) Brown's (Dr. T.Mjexperimentsin coal washing, 774 Bruckner, analyses of coal by, 761 Brune*s modification of meiler foimdations, 99 Brushwood also used as fuel, 2 and branches, elementary composition of, 10 Bull's (Marcus) determinations of specific gravity of wood, 7 experiments on relation of weight of wood to mass, 8 Bunsen, analyses by, 764 and Playfair's analyses of gases from Alfre- ton, 237 mixeis for gas and air, proportions of, 433 Bunsen's analyses of gases from Veckerhagen, 233 figures of pyrometrical heating effects, 359 investigations on flame temperatures, 367 observations on velotnty of flame propaga- tion, 369 Burch's experiments on reflection of light from candle flame, 371 Buruat and Dnbied's results examined by Kestner, 717 Burning in heaps, operation of, 98 Butyro-limnodic acid in peat or bog-butter, 12 Bystrom's pyrometer, 344 Cailletet's discovery as to exit gases, 434 Caking coal, general account of, 46 property of, in various coals, 122 Calcic carbonate in coals, 49 Calcining kilns, 636, 637 worked by gas, 636 Calcium chloride, solution &f, used for washing coal, 774 Calculation for volume of air from waste gases, 718, 719 of furnace efiiclency, 669, 670 Calculations for pyrometrical heating power of fuel, 347-352 Callou's comparison of ore and coal treatment, 771 Calorific eflSciency of different cokes compared by Bell, 193 power of peat, 21 value, defects of methods of estimating, 707, 708 method of estimating, proposed by Cornut, 709 by Eowan, 709 of different varieties of carbon, 707 of fuel by calculation, 337 of liquid fuel, 328-330 of oil gas, 329, 330 variation between experiment and cal- culation, 708 Calorimeters, 334, 335 used by Scheurer- Kestner and Meunier- Dollfus, 719 Calorimetric methods, Clement and Desormes, 333 ^ Favre and Silbermann, 334 Heisch and Folkard, 335 Lavoisier and Laplace, 332 Regnault, 334 Rumford, 332, 333 Schwackhofer, 335 Thompson, 334, 335 Calvert's (F. Grace) process for desulpburlza- tion, 124 Canachy, anal/aes of coal by, 748 Cannel coal, analyses of, 47, 48 or parrot coal, general account of, 47 supposed marine origin of its vegetable re- mains, 49 Carboleine, value of, as fuel, 365 Carbon and hydrogen the combustible elements in all fuel, 2 Carbon, calorific values of different states of, 707 heating power of, 355 in coal to amount of coke produced, relation of, 141-143 latent heat of gasification of, 356-358 value of, in coals, 711-716 variation in quantity of, in coal, 31 Carbonating furnace, Mactear's, 653 Carbonic acid in the gases the index of blast furnace, 474 solvent effect of, on coke, 194, 196, 198 Carbonic oxide, a source of fiame, 2 formed from carbonic acid, 2 heating power of, 356 pyrometrical heating effect of, 359 Carbonite, occurrence of, 119 Carbonization in heaps or pUes, 94 of pit coal, 119 Cardiff, trials of portable engine boiler at, 497 Carnegie's (Andrew) account of the natural gas territory, 286-288 Carnelley and Burton's pyrometer, 341, 342 Carnot's principle applied to steam boilers, 496 Cassels (J. L.), analyses of coal by, 755 Castel's investigation of contraction of gasc~, 74 Cellulose, progressive dehydration of, 23 Chabeaussifere, De la, kiln proposed by, loi Chagot's artificial fuel, 215, 216 Chambre des D^pnt^s, Paris, hot-air stovos in. 442 Chanter's grate, 515 Charbon ronx, 110-112 methodof making, in Charcoal, absorption of gases by, 108 amount of ash of, 109 and coke compared, 197, 198 black, average composition of , no INDEX. 783 Cliarcoal, burning by gas, 106 general principles of, 96, 97 in China. Russia, and Sweden, 101-106 in heaps, 94 time required for, 95 in kilna, 100-105 in meiler or mounds, 90 lu modified meiler, 98, 99 in mounds, time required for, 94 loss of bulk by wood in, 96 dust, spontaneous ignition of, no from dried and undried lignite, 119 from peat, 115 irom wood, peat, and lignite, 88-119 lor filters, 112 heaps or piles, sizes and construction of, 94>9S increased weight of, by ai-resting process of charring, no kiln, closed, and heated externally, loi proposed by X>e la Chabeaussifere, loi with air-holes in walls, loi with grate bart?, 100 kilns for recovery of tar, loi, 102 introduced by Schwartz into Sweden, 103 lignite, 118, 119 moulded vegetable, 112-115 mounds, sizes of, 92 peat, made by steam on Vignoles' plan, 117 percentage from various lignites, 119 process of burning in heaps, 95 in meiler, 93, 94 produce of, estimated by volume in different ways, 106, 107 produced by means of steam, 105 producer gas from, 278, 2S2 properties of, 107, 108 quantity consumed in charring the wood, 98 red, average composition of, 112 relative value for heating, 360 results of processes of Karsten, Stol^e, and Winkler, 89 slow process of making, compared with rapid, 88, 89 specific gravity of, 109 water absorbed by, loS yield of, 105 Chemical examination of exit gases, 435-438 furnaces, 651-692 view of coal, 31-34 Cherry or soft coal, general account of, 46 Chesterfield and Derbyshire Institute's experi- ments with mixture of gases, 70 Chevalier, analyses of coal by, 746, 748 Chevandier's analyses of European woods, 10 determinations of ash in wood, 9 examination of hygroscopic state of wood, 4 Chilton, Dr., analyses of coal by, 755, 757, 760 Chimney draught, expenditure of power to produce, 386 effect of blast pipe, 383 mechanically produced, 383, 384 Kankine's formulse for, 382 Chimney gases, 379 Chimneys, 378 IViction in, 380, 381 increase of draught by preventing radiation, 381 movement of gases in, 379, 380 ChiLVi, charcoal burning in, according to Kavanko, loi, 106 Clanny lamp indications of presence of fire- damp, 70, 71 Claridge and Koper's process of desulphurization, 123 Clark's (D. K.) abstract of Mnlhouse Society's trials, 721, 722 analysed of boiler performances, 723-726 investigations of boiler proportions, 723- 726 report on trials of gas firing, 565-569 tests of gas cooking utoves, 432 Classification, general, of wood into hard and soft, 5 of coal by size, 775, 776 of gas furnaces, 665, 666 of substances included in the term fuel, 2 ClemHon (T. G.), analyses of coal by, 754-760 Clerk's (Dugald) experiments on rates of ignition, 369 Clerk Maxwells formula for heat transmission, 495 Clerval, Ebelmen's analyses of gases from, 233 Cleveland blast furnaces, 639, 640 furnaces, plan for collecting gases, 230, 231 Close ranges or kitcheners, 397 Coal, American, analyses of, 749-760 American and British experiments with, 705 American, character and efificiency of, 696, 697 compared, for ash, with British, i;i tested in land boiler at Washingrton, 727 trials of, results of, 712 and coke, comparison of, 246, 247 gases from, 240-242 heat from, 243 heating power of, 239 in the blast furnace, action of, 244, 245 and gas fires compared, 536 annual production of, 45 anthracite, general description of, 57 / ashes, composition of, 766 *■ ash in, 49-51 ash of, aualyses of, 52 *^ ash of cannel, compared with that of shales, 48 \^ ash of, general character of, 51 basins, 41 beds, area of in diflEerent countries, 44 faults in, 42 bituminous and semi-bituminous of South Wales, analyses, 734-737 bituminous, in Asia, analyses of, 749 of England and Scotland, aualyses of, 733 of France, analyses of, 743-746 of Midlands andN. Wales, analyses of, 739. 740 of Yorkshire and Scotland, analyses of, 740-742 Coal-bricks, manufacture of, 214-226 Coal, British, jinalytt furnace oil, analysis of, 318 Cochon, analyses of coal by, 745 Coffey's still, 600-606 Blair,Campbell, and McLean's ari'angement, 602-604 method of working, 605, 606 Coke, absorption of water and gases by, 143 amount of, compareti with carbon, in coal, 141, 142 obtained from various coals, 140, 141 analyses of, 143 by Sir I. L. Bell, 193 and bye-products obtained from various ovens, amounts of, 181-192 INDEX. 7«5 Coke, comparative value of different Icinds, 192- 199 compared with charcoal and anthracite, 145-147 comparison of calorific efficiency, 193 with charcoal, 197, 198 compoiitlion of the aBlies of different Icinds of, 767 cost of making, 202 desulphurization of, 123 effects of air on different kinds of, 198 carbonic acid on different kindis of, 196, 198 heat on different kinds of, 195 liydrogen on different kinds of, 198 fires, advantages of, 374 from Continental coals, Karsten's results, 141, 142 general ohdervations on, 140 nature of, 143, 144 ovens, Aitken'e, for recovery of bye-pro- ducts, 182, 183 Appolt's, 174-176 at Seraing, Belgium, 2istillation, comparative results of, with canncl and bituminous coal, 48 destructive, general effects on coal, 32, 33 general principles of, 595 of mercury from sulphide, 607 of peat by steam, Vignoles' plan, 609 of peat, Keece's process, 203-208 of sawdust, tan, &c., retorts for, 608 of wood for vinegar, &c., apparatus for, 607, 608 section on, 595-609 Distilling apparatus, 596 pitch, 618, 619 Distribution of heat in kilns, 633, 634 of peat in countries of the world, 12 Dixon's results with gas-firing for boilers, 569- 575 Domestic fire-grate, 389 heiting, section on, 389-445 Donkln's (B.) method of tracing lost heat, 721 Doors, furnace, Prideaux's and Martinis, 521, 522 Dorn's still, 597, 598 Double fires proposed by Watt for smoke pre- vention, 513 Dowson's gas producer, 266 Draught, increase of, by preventing radiatton, 381 of chimneys, remarks on, 378-387 Diied woods all contain same elements, 3 Drouot, analyses of coal by, 746 Drying, 618 different kinds of wood, time required for, 4 kiln for fuel, 693, 694 Dryness and density of peat regulate its value, 13 Ducatel, analyses of coal by, 755 Dacomet's pyrometer, 341 Dufr^n^'s cupola, 647 Dufrenoy, analyses by, 733, 741, 768 Dundyvan blast furnace with arrangement for gases, 228 Dunn, analyses of coal by, 733 Dunnachie's brick stove, 412, 413 gas kiln, 627 Durocher, analyses of coal by, 747 Dust, coal, section on, 75-82 fuel furnaces, 77, 664 E Eames's apparatus for liquid fuel, 302 Early attempts at coking with recovery of bye- products, 178-180 forms of gas furnaces, 666 of mechanical stokers, 523 notices of gas fuel, 226 Ebelmen's analyses of gaRes from Clerval, 233 from Seraing, 236 from Vienne and Polit I'Ev^que, 235 of producer gases, 278, 279 Ebelmen and Sauvages' experiments on locomo- tive waste gases, 510 Ebelmen*s examinations of gases from coke ovens, 200, 20 X gas producer, 251 INDEX. 787 Ebelmen's view of appearance of interior of meiler dui-iiig- cliarring-, 97 of proportion of charcoal consumed in char- coal burning, 98 EcoDoniic values of Derbyshire coals, 699 of Lancashire coals, 700 of Newcastle coals, 699 of Scotch and other coals, 701 of Welsh coals, 698 Economy of dry fuel, 693 of gas burners, 416 of heat, sources of, in gas furnaces, 665 of the Yaryan apparatus, 595 Edinburgh Infirmary, steam heating system of. 485 Effect of coal under steam boilers, 702 of heat on fuel, general remarks on, 86-88 ot immersion of wood in water, 8 Effective heating by water and steam, compared, 479-480 Effects of flues for heating- with different fuels, 506 of surfaces on flames, 682-684 Efficiency and character of American coals, 696, 697 Efficiency of coal-flred furnaces, 658 of furnaces, calculation of, 669, 670 of gas cooking stoves, 431, 432 of gas stoves, 423-425 of regenerators, 669 Egg-ended boilers for gas-firing, 575, 576 Einhof 8 analysis of ash of peat, 15 Ekman's early gas furnaces, 672-674 gas producer, 252 Elementary composition of dried woods same as woody fibre, 3 of peat, 19 of wood, 10 of woody fibre, 3 Ellet, analyses of coal by, 757 Emission of heat by different substances, 405 by hot water pipes, 481-484 Emmott and Ackroyd's fire-damp indicator, 74 England and Scotland, analyses of bituminous coals of, 733 Estimates of percentage of water in fresh cut woods, 3 Estimating calorific value, defects of methods of, 707, 708 produce of charcoal by volume, different methods of, 106, 107 Europe, anthracites of, analyses of, 742 combustibles from, analyses of, 747, 748 European woods, analyses of, by Chevandier, 10 Evaporating pan, gas, 691 pans heated by waste heat, 586 Evaporation, amount economically obtained from boilers, 537 hy multiple effect, 590-595 range of temperatm e in, 590, 591 vacuum in, 590 by steam, 587-607 in gas- and hand-fired boilers compared, 546, 556-561, 565- 569 in triple-ofl'St apparatus, 590-592 method of, in the Yaryan apparatus, 592 of brine by gas, 587 in open pans, 585 of gas- and hand-fired boilers compared, 554, 556 of the KiUioux system, 590 of vitriol in open pans, 584 section on, 583-607 surface, for weak liquors, 586 tests of the value of coals for, 711 Evaporative results at Keyham Dockyard and at Washington, 727 from Newcastle and Welsh coals, 728 obtained by L. E. Fletcher, at Wigan, 724-727 by Sir F. Bramwell and Dr. Eussell, 729, 730 with portable eng-ine boilers, 729 with D. Rowan's boilers, 580, 581 with Haupt's gas-fired boiler, 554, 556 with land boilers using Hindley Yard coal, 724, 725 Evaporative value of hydrocarbons, by Dr. B, H. Paul, 295 of peat, Anderson's experiments, 21 Evaporator, surface, with straight steam pipes, 589 the Yaryan, 592 Evaporators, open steam, heated by pipes, 588 Evrard's coal washing- machine, 777 Examination of waste gases from locomotives, .510 Exhaustion of air, effect on fire-damp, 66, 67 Exit gases and soot, 434-438 Experiments and investigations hy Scheurer- Kestner, 717-721 Experiments on coal dust, by Galloway, Hall and Clark, Marreco and Morison, Sir F. Abel and Hoyal Commit-sion, Chesterfield Institute, 77-80 Explosive mixtures of coal gas and air, 70 of marsh gas and air, 69 External brick fhrnace to boiler at St. HoUox, 514' F Facility of ignition depends on constitution and texture, 2 Fan blast for air supply of fires, 383 Faraday's report on coal-dust, 75 Fatty substance in peat, 1 1 Faults in coal beds, 42 Favre and Silbermann's calorfmeter, 334 Felling wood for fuel, average time suitable for, 5 Fichet's arrangements for Cornish boilers, 545, 546 for French or elephant boilers, 544 for vertical boilers, 546 experiments on boiler firing by gas, 543- 550 tables of analyses and temperatures, 547- 550 Filter charcoal, 112 Fire-brick burning, gas kiln for, 627 stoves, 410 Fire-damp, 59-75 analyses of, 61 blowers, 62-68 effect of a blown-out shot on escape of, 67 of exhausting air at surface of coal, 66 of exhausting atmosphere of coal mine, 67 of increased depth of working, 68 experiments on ignition by sparks, 60, 61 explosive mixtui'es of marsh gas and air, 69 explosive proportions of, Coquillon's re- sults, 69 Chesterfield and Derbyshire Institute's results, 70 Royal Commissioners' results, 70 W. Galloway's results, 70 3 E 2 788 INDEX. Fire-damp, formation of, 62 indicators, 70-75 iufluence of atraosp]ierie pressure on, 66, 67 natural sources of, 59 occurrence of, 62-68 pressures of escaping* gas, 68 proportions of. Indications from Clanny lamp, 70, 71 from Pieler lamp, 72 specific gravities of gases composing, 69 temperatures necessary for ignition of, 61 Fire-erate, domestic, 389 Fire-places, Arnott'a, 394-396 Deaarnod's, 391 open, 389-396 Rumford'a, 390 Sylvester's, 391-394 First charter for digging" coal in England, 41 for digging coal in Scotland, 41 Flame, action of, in furnaces, 682, 683 Berthelot's corrections of Bunseu's figures, 368 Bunsen's investigations on temperature of, Deville's investigsCtions on lemperature of, 366 effects of surfaces on, 682-684 extingulslied in boiler tubes, Anderson's experiments, 577 length of, produced by dust, 80 longest, produced by certain fuels, 2 luminosity of, 370-373 afEected by density and' presBure, 371, 372 nature of, 365 produced by carbonic oxide, \e. propagation of, 368-370 experiments by Davy and by Coquillon, 69 by Chesterfield and Derbyshire Institute of Engineers, and by Koyal Commission on Accidents in Mines, 70 by W. Galloway, and Kreischer and Winkler, 70, 71 property of burning with, connected with hydrogen, 2 section on, 365-373 space for boilers fired by gas, 551, 552 temperature of, 366-368 varieties of fuel which burn without, 2 Fletcher's (L. E.) evaporative results at Wigan, 724-727 Fletcher's (T.) gas cooking stoves, 427, 428 gas stove or gas fire, 418, 419 Flue-', advantages of, for heating boilers, 505 Footc's apparatus for liquid fuel, 301 Forced combustion, 384-389 plans for using, 387 Ford's (S. A.) analyses of natural gas, 290 Foreign coals, analyses of, 53-56 Forging furnaces, fuel consumption in, 6<;j^ 658 Formation of fire-damp, 62 of peat or turf, natural process of, 11 Forms of blast furnaces, 638, 639 of Siemens' furnaces, modifications in, 680- 683 Formulae for absolute heating effect, 358, 359 Foster's (W.) estimate of nitrogen in coal, 248 Foulis' gas fire, 402, 403 France, bituminous coala of, analyses of, 743- 746 investigations of fire-damp and coal dust, 69-76 lignites of, analyses of, 768 France, peat marsh of Montoire, in, 12 public buildings of, heating of, 4S7 turf from, analyses of, 769 Frankland and Percy on flame luminosity, 371 Frankland'8 researches on flame, 371, 372 Frazer (J. F.), analyses of coal by, 742, 759, 760 French bee-hive coke ovens, 166 coals, average produce of coke, 143 Frew's pyrometer, 347 Frisbie's mechanieal stoker, 527-529 Fuel, all varieties originally derived from woody fibre, 2 application of, general remarks on, 373 to vaporization, 494 artificial or patent, 208-226 calorific value found by calculation, 337, 707, 708 classification of substances thus called, 2 combustible elements of, 2 consumption of, in puddling and forging furnaces, 657, 658 in relation to grate area, 504 in Kiley's gas cupolas, 678 distributor, Payen's, 515, 516 economy of dry, 693 effect of heat on, general remarks, 86 88 moisture in, 694, 695 expenditure of, in kilns, Guthrie's table, 635 facility of ignition depends on constitution and texture of, 2 from Russia, analyses of, 769 gaseous, 226-293 heating effects of various kinds of, 353 355 heatmg power referred to volume, 338 laws of heat production important in apply- ing, I liquid, section on, 293-330 locality of production of heat by various- kinds, 2 natural gas as a, 286-293 practical effect of, 692-732 property of burning with flame due to hy- drogen, 2 pyrometrical heating effect, 339 quantity required for dry distillation of wood, lOI rapidity of ignition favoured by presence of hydrogen, 2 relative value dependent on proportions of elements, 2 relative value of, 332 relative values of different kinds for warm- ing, 695 spent tan and straw used as, 330, 331 use of, in manufactures and agriculture, i. drying, 618, 620 value of, diminished by prraence of ash, 2 in a finely divided state, 364, 365 varieties of, which burn without flame, -^ wealth of Britaiu derived from, i Fuels, different, examined microscopically, 35-39- minor, 330, 331 which produce the longest flame, -^ Furnace, Bicheroux, 685 blast, section on, 637-642 Bo^tius, 684 cupola, 642-650 doors, Martin's, 522 efficiency, calculation of, 669, 670 for distillation of mercury from sulphide, 607 for silver residuums, Bichardson's, 651, 652. for zinc ore, 662-664 gps annealing, 691 gas blowpipe, for puddling, 674-676 INDEX. 789 Fnrnace, Gorman's, 685, 686 hand-worked pan anil roaster for salt-cake, 654 Jones and Walsh's, 653 plnrt-pressure, 654, 655 Ponsaid'B, 687, 688 Price's retort, 685 Kadcliffe's, 689, 6go results of working', 690 leverberatory, 652 Siemens', for melting glass, heat distribu- tion in, 670 gas, 679-681 Smith-Casson's, 685 Swindell's, 685 the Mactear, 653 the St. Bede chemical, 656, 657 Wedding's, at Berlin Mint. 673 Furnaces, action of flame in, 682, 683 blast, waste gases from, 227 coal-fired, efficiency of, 658 for dust fuel, 664 for lead and silver ores, 662-664 for natural gas, 293 fupl consumption in, 657, 658 gas, 664-692 gas blowpipe, used early in Sweden, 670- 674 heat conservation in, 660 heat distribution in, 662 heat production and utilization in, 659, 660 iron smelting, in America, use of coke in, 147 metallurgical and chemical, 651-692 modification in forms of, 68 1 puddling and forging, 657-660 section on, 632-692 Siemens' modified, 682 Sudr^'s reverberatory, 661 Wilson's (E. B.), 685 Fyfe, analyses of coal by, 741, 742, 765 Fyfe's determinations of volatile to non-volatile matter in coal, 34 G Galloway's (W.) experiments on mixtures of gases, 70 experiments with coal-dust, 'j'j remarks ou Prussian results with coal-dust. 81 Galton's grate, 397, 398 Garella, analyses of coal by, 746 Gas annealing furnace, 691 Gas as a source of heat, application of, 399 Gas blowpipe, arrangement for puddling, 674 676 burners, tests of, 414, 415 coke, plan for using in gas-making, 376 cooking stoves, 426-432 tests of efficiency of, 431, 432 cupolas, 647, 676-678 evaporation of brine by, 587 Gas-fired and baud-fired boilers compared, 546, 554, 556-561, 565, 569 Gas-fired boiler, Beaufum^'s, 539, 540 Hartmann's, 551 Gas-fired boilers, 535-582 Fichet's experiments, 543-550 Gadsden & Co.'sarrangcmeuts, 566-575 general considerations, 535 Haupfs, 551-556 in America, 566-575 Gas-fired boilers, Lancashire and Coi-nish, 562, 563 Minary's, 542 Rowan's arrangements, 575-582 used in Darby's trials, 556, 557 using waste gases from blast furnaces, 538, 539 Gas calcining kilns, 636 evaporating pan, 691 kiln, Dunnachie's, 627 malt kiln, 621, 622 pottery muffle. 628 salt-cake furnace, 653, 654 Gas fires, 400-403 cost of heating by means of, 401 . Foulis', 402, 403 Hislop's, 401 Siemens' coke, 399 Verity's, 402 Gas-firing for boilers, regenerators for, 692 for gas retorts, 610-619 general remarks on, 375 Gas from salt and other springs, composition of 59' 60 Gas furnace, blowpipe, at Treveray, 674 the Siemens, 679- 681 Gas furnaces, blowpipe, Sutherland's, 674 blowpipe, used in Sweden, 672-674 classification of, 665, 666 disadvantages of attached generators, 665 early forms of, 666 early Swedish, 670-674 economy of heat in, 665 loss of heat by separate generators, 666, 667 section on, 664-692 use of heated air in, t^j Gas, incinerators worked by, 586 Gas-kiln for calcining ore at Goltness, 228 Gas manufacture, coals for, compared, 35 muffle for heating metal, 692 natural, analyses of, 290 as fuel, 286-293 average pressure of, 288-290 development of its use, 287 furnaces for, 293 heat value of, 290-292 used for firing boilers, 575 Gas, producer-, Beilby's analysis of, 284 Keate's analysis of, 285 Magnus Troilius's analyses of, 283 Philips', analyses of, 283 Ponsard, P^risse's analyses of, 281 Siemens', Boistel's analysis of, 280 Leblanc's analysis of, 282 St. Gobain, analysis of, 280 Wilson, Stead's analyses of, 282, 283 Gas-producer, Beaufum^'s, 253 Benson's, 255 Bdrard's, 254 Bischof's, 250 Dowson's, 266 Ebelmen's, 251 Ekman's, 252 Grobe and Liirmann's, 267. 268 Healey's, 270 HowHon's, 271 Kidd's, 259 Lowe and Strong's, 259-262 Lun din's, 254 Minary's. 256-258 Miiller's and Fichet'.-, 271, 272 Ponsard's superhcdted, 688 Rowan's, 285 Siemens', 254 790 INDEX. Gaa-producer, Siemens' circular, 270 euperheated, gain of heat by, 688 Sutherland's, 268-270 Tervet's, 273 Tessl^ du Motay'a, 265 Thwaite's, 273-275 water-gas, 262 Wilson's, 263-265 Young: and Beilby's, 275, 276 Gas-producers, 250-275 use of lignite in, 27 Gas retorts, methods of heating, 609-619 Gas stoves, 413-432 tests of comparative efficiency, 423-425 used for evaporating brine, 587 Gas, water-, Lauglois and Frankland's analyses of, 285 Moore's analysis of, 285 Gaseous combustibles, 226-293 fuel applied to charcoal burning, to6 fuel for boilers, advantages of, 535 mixtures, temperatures of ignition of, y^ Gases absorbed by charcoal, quantities of, 108 chimney, examination of, by Kestner, 717, 718 escape of, in coking process, 148, 149 escaping from locomotive boilers, 510 exit, and soot from grates and stoves, 434 foiToing the mixture called fire-damp, specific gravity of, 69 from blast furnaces, 227 composition of, 232-250 from coal and coke in the blast furnace, 240-242 from coke ovens, Ebelmen's experiments, 200, 201 hot, velocity of, fi-om boilers, 503 motion of, in chimneys, 379, 380 occluded in coal, 82-86 in coke, Storer and Lewis* results, 143 waste, from blast furnaces, methods of col- lecting, 227-232 soda lime best absorbent for, 719 used to calculate volume of air used, 715-719 Gasification of carbon, latent heat of, 356-^58 Gaultier, analyses by, 767 GaiintletVs pyroiheter, 342 Gay-Lussac, analyses by, 748 General character of ash of coal, 51 of ash of wood, 8 classification of wood into hard and soft kinds, 5 principles of distillation, 595 remarks on mounds and heaps, 96-100 result of analyses of air-dried and kiln-dried wood, II Generators, attached, diaadTantag'es of, 666 separate, loss of heat by, 666, 667 Germany, analyses of coal from, 763, 764 of turf from, 761, 769 Geological features of the lignites, 40 occurrence of coal, 39 position of coal, 24 view of coal and coal formation, 28, 29, 30 Glazing art pottery by gas firing, 628 Goddard, analyses of coal by, 757 Godfrey and Howson 'a puddling apparatus, 674- 676 Gorman's furnace, 685, 686 Goulishambarolf's analyses of Kussian and American oils, 299 Graeger, analyses of coal by, 763 Grant, Ritchie & Co.'s coal-washing machine, 136-139 Grate, Bodmer's screw, 516-519 Chanter's, 515 surface, relation of, to fuel consumption, 504 Townsend's travelling, 520 Green's method of drying peat, 118 Greiner and Erpf's cupola, 648-650 Griesheim. moulded peat from, 18 Grobe and Liirmann's gas producer, 267, 268 Grouyelle's system of heating and veutilatlcn, 488 Griiner, analyses by, 744-746 Guthrie's diagram of heat distribution in kilns, 633j 634 kiln, 631-635 limestone kiln, 636 table of fuel expenditure in kilns, 635 H Halliday's close retorts for distilling sawdust, &c., 608 Hall's & Clark's experiments with coal-dust, 77 Hand- worked pan and roaster furnace, 654 Hanoverian peat, weights of, by Karmarsch, 18 Hans Danchell's estimate of area of peat in Britain, 12 Hartmann's plan of gas-firing for boilers, 551 Hassenfratz's determinations of specific gro-v^ity of charcoal, log Haupt's plans of gas-firing for boilers, 551-556 Haworth and Horsfall's "Todmorden" stoker, 531 Hay's (G.) analyses of natural gas, 290 Hayes (W.), analyses of coal by, 755 Healey's gaa producer, 270 Heaps and mounds, general remarks on, 96-100 Heaps, charcoal burning in, 94 operation of burning in, 98 sizes and construction of, 94, 95 Heat conservation in furnaces, 660 distribution in puddling and heating fur- naces, 662 in Siemens' glass furnace, 670 of, in blast furnaces, 641 of, in kilns, 633, 634 economy of, in gas furnaces, 665 effect of, on different kinds of coke, 195 on fuel, geceral remarks on, 86-88 expenditure of. in warming air in houses, 377 from coal and coke in the blast furnace, 243 gain in, by Tonsaid's superheated gazogene, 688 loss of, by heating waste gases, 386, 387 by using separate generators, 666, 667 in reversing regenerators, 669, 670 losses of. In trials, 721 lost by radiation accounted for by Donkin's test, 721 production, laws of, important in applying fuel, I production and utilization in puddling fur- naces, 659, 660 rate of transfer of, to water in boilers, 537 transmission of, in boilers, 502 theory of, 331 transfer of, through boiler plates, 501 transmission of, laws of, 495 " unaccounted for in Bramwell's results, 731 useful, in bloat furnaces, 473, 474 value of natural gas, 290-292 where produced by varieties of fuel, -^ Heating air supply for combustion, 387 by channels or flues, 434 INDEX. 791 Heating by hot air, 434 by means of gas fires, cost of, 401 by mechanical means, Frof. Thomson's theory, 494 by radiation, Mr. F. Siemens' theory, 681- 684 by water and steam, 478-503 coal in vacuum, effects of, 86 domestic, section on, 389-445 effect dependent on oxygen. Welter's theory, 335) 33^ effects (absolute, specific, and pyrometrical) of coal, 354 of coke, 354 of furnace gasPS, 354 of lignite, 353, 354 of peat, 20, 353 of peat cbarcoal, 354 of producer gases, 354 of wood, 353, 692, 693 of wood charcoal, 354 of various combustibles, 353-355 pyrometncal, of fuel, 339 gas retorts, 609-619 by gas, Klonne's system, 615, 616 modified by Stevenson. 617 Muller and Eichelbrenner's plan, 611, 612 original Siemens' system, 6ro, 611 Siemens' plan at Glasgow, 617 system of Liegel, 612-614 of Schilling and Bunte, 613-616 systems of Didier and Hasse, 612, 613 Valon's plan, 614 Wilson's plan, 618, 619 metal, gas mutfie for, 692 of Manchester Royal Exchange, Pantech- nicon, &c., 445 448 power of carbon and hydrogen, 355 of carbonic oxide, marsh gas, and olefiant gas, 356 of coal and coke in the blast furnace, 239 of peat charcoal, 116 of various combustible substances, 333 of wood of different kinds, 333 ratio of effective, to air. 405 surface and cost of bot-blast stoves, 471 of evaporators wirb steam jackets, 587 of steam pipe coil, 587, 588 of stove?, 404, 405 value, relative, of various substances as compared with that of carbon, 334 wood to different temperatures, effects of, 5 Beaton's cupola, 645 Heisch and Folkard's calorimeters, 335 Henderson's mechanical stoker, 525, 526 Herbertz's cupola, 645, 646 Hesse, experiments of Industrial Society of Grand Duchy of, 505 Hiflau in Styria, yield of charcoal from conife- rous wood, 105 Higgins, analyses of coal by, 755 Hiudley Yard Coal, evaporative results from, 724, 725 Hislop's gas fire, 401 Hitchcock, analyses of coal by, 749 Hofimann's coke ovens, 189-191 kiln, 629 method of working, 630 Holland, depth of peat in, 12 Holroyd Smith's "Helix" mechanical stoker, 53° Horizontal meiler, 91 Hornung's (C.) resume of cupola design, 642 Hot air and capacity of furnace, relations between, 475 for Turkish baths, 449, 450 stoves, 439-450 Hot blast, advantages of, 476 box-foot ovens, 457 carbon replaced by, at different tempera- tures, 477 circular stoves, 460, 461 concentric-pipe ovens, 458 Cowper's regenerative stove, 463-466 early forms of stoves, 453-455 fire-brick regenerative stoves, 463-471 influence of pressure of, in furnaces, 477, 478 introduction of, in iron-making, 450-452 invention' of, by Neilnon, 452 Massicks and Crooke's stove, 468-470 Nellson's first apparatus, 453 oval stoves, 462 pistol-pipe stoves, 460 practical limits to use of, 477 principles of, 470-478 pyrometers for, 347 saving in fuel by introduction of, 450, 451 siphon-pipe ovens, 458 stoves, 450-478 volume and heat of, when substituted for carbon, 477 Whiiwell's stove, 466-468 Hot water circulation, principle of, 478, 479 House of Commons, fonner, heating of, 492 House of Peers, Mr. Barry's plan for warming and ventilating, 493 Howard's plan for smoke prevention, 513 Howson's puddling apparatus, 674-676 gas producer, 271 Humic acid in peat, 13 Hungary, anal> ses of coal from, 762 Hunter's investigations on absorptive power of charcoal, 108, 109 Hydrogen and cai-bon the combustible elements of all fuel, 2 and oxygen, variation of quantity in differ- ent coals, 31 effects of, on different kinds of coke, 198 excess of, in woods, 362-364 heating power of, 355 in large proportion favourable to rapid ignition, 2 presence of, regulates property of producing fiame, 2 supposed to be the cause of the caking property of coal, 122 value of, in coals, 711-713 Hygrometric water, mean quantity of, in non- resinous woods, 4 in resinous woods, 4 minimum amount of, in wood, when at- tained, 4 Hygroscopic state of different woods, examina- tion of, 4 Ice calorimeter, 332 Ignition and inflammation, speed of, 369, 370 Ignition, facility of, depends on constitution and texture, 2 of fire-damp by sparks, experiments on, 60, 61 of fire-damp, temperatures necessary for, 6i of gaseous mixtures, temperatures of, 75 792 INDEX. Ignition, rapidity of, hydrog-en favourable to, -j. Immersion of wood In water, loss by, 8 Imperfect coking, diagram of, 144 Importance of amount of water in wood, 3 Incinerators used in paper worlcs, 586 Index of worliing of blast furnaces, 641 Indications given by tlame of the Clanny lamp of proporllona of fire-damp, 70, 71 Indicator diagram for boiiers, 498 Indicators of tire-damp, 70-75 Ingredients of moulded charcoal, 112 Interior of meiler during charring, appearance of, according to Ebelmen, 97 Introduction of coal as fuel in England, Scot- land, France, &c., 41 Ireland, area and depth of peat in, 12 Ireland's cupola, 643 Iron, comparative conductivity for heat, 404 manufacture, uee of lignite in, 28 permeability (when hoi) to gases, 404 Jackson (C. T.), analyses of coal by, 742-760 Jaeckel, analyses by, 769 Jameson's colte ovens lor recovery of bye-pro- ducts, 183-1B5 Jaumain's examinations of , gases from Mnr- chiennes and Mouceau, 249, 250 Johnson (W. R.), analyses of coal by, 733-760 Johnson's analyses of ash of American anthra- cites, 58 Johnson's (W. K.) Investigation of American coals, 702 Jones (Dr.), analyses of coal by, 755 Jones and Walsli's revolving furnace, 653 Juckes's mechanical stoker, 523 Juncker's experiments on the yield of charcoal, loS K Kahl's pyrometer, 347 Kaue and Sullivan, analyses of peat by, 20 observations on moisture in peat, 14 table of analyses of ash of peats, 16 27 specimens of peat, description and local- ity of, 17, 18 KarapetoS's apparatus for liquid fuel, 309 Karmarsch, coinparatlve weight of recent and old peat by, 12 Karmarscli's determinations af specific gravity of woods, 7 of weights of Hanoverian peat, 18 Karsten, analyses by, 733-760 comparative value of coal and peat for evaporation, 20 Karsten's estimations of ash in wood, 9 experiments on produce from meilers, 105 method of charring wood compared with others, 88, 89 observations on loss of water by drying peat, on produce of coke, 140, 141 results, coke from Continental coals, 141, 142 Kavanko's account of cliarcoal-burning: in China, loi, 106 Keates' (T. W.) aaalyses of producer gas, 285 Kerr and Mitchell's coal-washing machine, 138- 140 Kerwan, analyses of coal by, 733 Kestner's experiments, 717-721 Keyham Dockyard, evaporative results obtained at, 727, 728 Kidd's gas producer, 259 Kiln, continuous, Guthrie's, 631-635 for charcoal, closed and heated externally, lOI wich air-holes in walls, loi with grate-bars, 100 for drying fuel, 693, 694 for fire-bricks, gas-fired, 627 for porcelain and pottery, 625 for red bricks, Hoffmann's, 629, 630 for stoneware, 626 proposed by Be la Chabeaussiere, loi Kilns, charcoal burning in, 100-105 distribution of heat in, Guthrie's diagram, 633, 634 expenditure of fuel in, 635 for limestone, 634, 636 for malt, 621-623 for peat charcoal, 115, 116 *" Kind^ of gas furuaces, 665, 666 of regenerators, 668 of wood, differences between, 3 Kl<3nne*s system of heating gas retorts, 615. 616 Koettig, analyses of coal by, 763 Kraus' (M.) statement of heat distribution in Siemens' furnace, 670 Kreischer and Winkler's experiments with safety lamps, 71 Krigar's cupola, 646 Krigar's (Henry) cupola, 647 Kubnert, analyses of coal by, 747 La Cava, analyses of coal by, 764 Lancashire aud Cheshire coal^ tested in marine boiler at Keyham, 727 boilers gas fired, S56-564 Lancashire coals, analyses of, 55 economic values of, 700 Langlois and Frankland's analyses of water-gas, 285 Latent heat of gasification of carbon, 356-358 Laws of heat production important in applying fuel, I Lea (M. C), analyses of coal by, 757, 758 Lead and silver ore furnaces, 662-664 Lead ore reducing hearth, 637 Leblanc's (Felix) analyses of Siemens' producer gas, 282 Le Chatelier, analyses by, 747 Length of boiler tube to permit gas to burn in it. 577 Lents's apparatus for liquid fuel, 305, 306 Leplay, analyseij of coal by, 746 Liegel's plan of heating gas retorts, 612, 614 Light, quality of sunlight refltcted from flames, 371 (foot-note) Lignite, Austrian, analyses of, 767 charcoal, 118, 119 compressed into blocks, value of, 28 from Saxony, analyses of, 767 German, analyses of, 768 or brown coal, varieties of, 24 use of, in blast furnaces, 28 in iron manufacture. 27 in steel making, 28 on railways, 28 Lignites, geological features of the, 40 of France, analyses of, 768 Limestone kilns, 634-636 Liquid fuel, calorific value of, 328 330 INDEX. 793 Liquid fuel, chief sources of supply, 299, 300 DeviUe's beat value of oils, 297 extent of oil productiou in Kussia, 298, 299 methods of using, 300-316 Archer's, 302 ArtemefE's, 307 Aydon's, 303-305 Eames's, 302 Foote's, 301 Karapetoff's, 309 Lents's, 305, 306 Nobel's, 308 Riley's, 315 Selwyn'a, 320 Thwaite's, 317 Urquhart'a, 312. 313 WittenstrOiu's, 313-316 Paul's (Dr.) inv&itigation of effective heat, 296, 297 production of oil in America, 293 Kankine's examination of theoretical effi- ciency of, 294, 295 results obtained with, 316-327 section on, 293-330 Litharg^e test, comparative value of, 715 Liveiug'a fire-damp indicator, 74 Llangeunech coal, properties of, 497 Locomotive boiler, 507 Locomotives, etTects and proportions of blast pipes in, 511 examination of waste gases from, 510 Loss of heat by heating waste gases, 386, 387 in reversing regenerators, 669, 670 in use of solid fuel, 374 in warming air of dwellings, 377, 378 of power by use of chimney draught, 386 of water by compressing peat, 14 of weight in wood by immersioa in water, 8 Losses of heat in trials, 721 Lowe and Strong's gas producers, 259-262 Lowering of boiling point of water by \ ..:;uum, 590 Liihrich's coal-washing plant at Bochum, 132- 136 Luminosity of flames, 370-373 Lundin's gas producer, 254 M MacDougall's mechanical stoker, 532, 533 Machines for washing coal, 125-140 Mackworth's coal-washing mactiine, 130 Mactear's revolving furnace, 653 Main's gas cooking stove, 426 Mallard and Le Chatelier's experiments on tem- peratures of ignition, 75 Mallard's ob«ervaiions on the rate of flame pro- pagation, 369 Malt kiln, Bavarian, 623 fired by gas, 621, 622 kilns for drying, 621-623 Manchester Pantechnicon, heating of, 447, 448 Royal Exchange, heating of, 445, 446 Manufactures dependent on heat, i Marcher, analyses ox coal by, 747 Marchiennes, analysis of gas from, 249 Marcus Bull's determinations of specific gi-avity of woods, 7 experiments on relation of weight and mass of wood, 8 Marine boilers, 508, 509 Marreco and Morison's experiments with coal- dust, -^7, 79 Marsaut'n coal-washing machine, 'j'jj Marsant's diagi'am of coal washing process, 774 Marsh gas, heating power of, 356 Martin's furnace doors, 522 Massicks and Crooke's hot-blast stove, 468-470 Mass of wood in relation to its weight, 8 Materials for the construction of stuves, 403, 404 Mather (W. W".), analyses of coal by, 755 Maui'ice's fire-damp Indicator, 73 Maw's (W. H.) remarks on combustion under pressure, 388, 389 Maximum state of dryness of woods, when attained, 4 Mayer's results from charring undried lignite, 119 Mazas Prison, heating arrangements of, 487-490 Mechanical draught, 383 stokers, 515-535' Aula's, 533, 534 Bodmer's screw grate, 516-519 Deacon's, 524 Dillwyn Smith's, 523 Frisbie's, 527-529 Haworth & Horsfall's. 531 Henderson's, 525, 526 history of development, 523 Holroyd Smith's, 530 Juckes', 523 McDougall's, 532, 533 Payen'Sj 515, 316 Player's, 534 Prideaux's tire doorei, 521 Proctor's, 533 Townsend's travelling grate, 520 Vicars', 523 Vicars' (T. & T.), S3I) 532 Wilson and Smith's, 523 Megass used a-* fuel, 330, 331 Meiler, formation of, 90,91 foundations, Brnne's modified construction of, 99 horizontal, 91 interior of, during charring, according to Ebelmen, 97 or mound method of making charcoal, 90 process modified at Hiflau and other places, 98,99 stationary, 99 vertical, 92 with complete covering, 93 Melting points of various substances, 120, 121, 341 Melting, rate of, in Riley's gas cupolas, 678 Mercury, distillation of, from sulphide, 607 Metallurgical furnaces, 651-692 Metal stoves for solid fuel, 409, 411 Method of estimating calorific value proposed by Cornut, 709 by Rowan, 709 of evaporation in triple eflgt apparatus, 590-592 of working blast furnaces, 639, 640 Coffey's Biill, 605, 606 Hoffmann's kilu, 630, 631 Methods of collecting waste gases from blast furnaces, 227-232 of determining the physical character of coke, 149- 152 of estimating calorific value, defects of, 707 708 ' of heat conservation in furnaces, 660 of heating apartments and dwellings, 389 of mixing gas and air for combustion, 551, 552 of recovering ammonia and tar from furnace gases, 232 794 INDEX. Methods of using liquid "fuel, 300-316 Meyer's experiments on iguition of fire-damp by sparks, 60, 61 Meyer's (E. von) results of examinations of gases occluded in coal, 83-85 Meyer's (F.) experiments on yield from meilers, 105 Meynier's coal-washing machine, 127, 128 Microscopical character of coal, 37 of peat, 36 examiuation of fuels, 35-39 Middlesex County Lunatic Asylum, heating of, 483 Midlaaids and N. Wales, analyses of bituminous coals of, 739, 740 Miller's (John, & Co.) copper still and worm, 596, 597 Minary's apparatus for boiler firing by gas, 542 examination of principles of forced draught, 3B5. 386 gas producers, 256-258 Mineralogical characiers of coal, 30 Minimum of hygrometric water in wood, when attained, 4 Minor fuels, 330 Modifications in construction of furnaces, 681 of Siemens' furnaces, 680-683 Moisture, effect of, in fuel, 694, 695 Monceau, analysis of gas from, ;25o Moore's (Dr. G. E.), analyses of Strong's water- gas, 285 Morin's (General) proportions of heating surface of stoves, 405 Moulded peat from Griesheim, weights of, 18 vegetable charcoal, 112-115 Mounds, charcoal, sizes of, 92 process of burning charcoal in, 93, 94 Mounds and heaps, general remarks on, 96-100 Movement of gases in chimneys, 379, 380 Mulder, resins discovered in peat by, 13 Mulder's statement about soda-lime for absorb- ing waste gases, 719 Mulder and Begnault, analyses of peat by, 19 Mulhouse, Industrial Society of, comparative trials of boilers, 721, 722 Kestner's results published by, 720 results of Industrial Society of, examined, 717 Muller and Eichelbrenner's plan of beating gas retorts, 611, 612 Miiller and Fichet's gas producer, 271, 272 Multiple effect evaporation, 590-595 Murrie's pyrometer, 347 Mushet (D.), analyses of coal by, 733-747 statement about hot blast by, 450 N Napier's stove, 411 Natural gas, analyses of, 290 area of productive territory in America, 287- 289 as fuel, 286-293 average pressure of, 288-290 depth of bores, 288, 289 development of its use, 28/ heat value of, 290-292 period during which it has been used, 286, 287 used for firing boilers, 575 Natural process of formation of peat or turf, 11 sources of fire-damp, 59 Nature of ash of cannel coals and shales com- pared, 48 Nature of coke, 143 compared with charcoal and anthracite, 145, 146 of flame, 365 Nau's experiments on water absorbed by char- coal, 108 Neilson's invention of hot blast for iron-making, 452 Nendvitch, analyses by, 762 Newcastle and Welsh coals, evaporativeTesults from, 728 Newcastle coals, analyses of, 53-56 economic values of, 699 Newcastle-on-Tyne Infirmary, heating arrange- ments of, 490, 491 New South Wales, analyses of coals of, 761 New Zealand coals, analyses of, 760, 761 Nitrogen in anthracite, 57 in brown coal, 26 in coal, 52 distribution of, accoiding to W. Foster, 248 in peat, by Kane & Sullivan, 20 Nobel's apparatus for liquid fuel, 308 o Observations on ash in peat from many countries of Europe, 14, 15 Occurrence of carbonite, 119 of fire-damp, 62-68 Oil, blast furnace, from Coatbridge, analysis of, 318 composition of American and Bussian, com- pared, 299 production of, in America, 293 in Kudsia, 298, 299 Oil-gas, calorific value of, 329, 330 Oils, heat value of, 297 Older peat, general description of, 12 Olefiant gas, heating power of, 356 Olmsted, analyses of coal by, 758 Open fire-places, 389-396' pans, evaporation in, 583-587 steam evaporators heated by pipes, 588 Ore hearth for reducing lead ore, 637 Origin of cannel coal vegetable remains, sup- posed marine, 49 Otto's coke ovens, 188-192 Outbursts or discharges of fire-damp, 63-68 Oven for baking bread, 624 Ovens, coking in, 162-192 Owen, analyses of coal by, 760 0:sygen consumed by coals as a test of their value, 711-713 Paillette, analyses of coal by, 747 Pan, vacuum, 589 Pans, evaporating, heated by waste heat, 586 open, for evaporation, 583-587 Parts of trees called "wood," tor fuel, 2 Patent fuel, Wylam's, Warlich's, Be88cmer's,&c., 208-226 Paul's (Dr. B. H.) investigation of effective heat of liquid fuel, 296, 297 Payen's fuel distiibutor or mechanical stoker, S15. 516 Peat, analyses of ash of, 15 analyses of, by Kaue and Sullivan, 20 by Eegnault and Mulder, 19 by Ronalds, 20 INDEX. 795 Feat, antiseptic qualities of, ii area of, in Britain and Ireland, 12 ash of, 14 composition of, 16, 766 Kane and SulUvans table of compo- sition of 27 specimens, 16 calorific powei' of, 21 charcoal, 115 ash of, 116 heating power of, 116 kilns, 115 relative value for heating, 361 Vig-noles' process for, 117 chemical composition of ash of, from Ire- land, 16 classification of, into recent and older peat, 12 compressed, Stones' process, 116 compression of, introduced for improving- quality, 14 density of, 18 depth of, in Holland and Ireland, 12 description and locality of Kane and Sulli- van's specimens, 17 dLffierence in composition from wood, ig distillation of, 203-208 by steam, Vignoles' plan, 609 distribution of, in countries of the world, 12 drying, Green's method, 118 drying and charring, Kogers' system, 117, 118 elementary composition of, by Kegnault and Mulder, 19 estimates of percentage of ash in, 14, 15 evaporative value of, 21 fatty substance in, called bog-butter, 11 Hanoverian, evaporative value of, 361 weights of, by Karmartsch, 18 heating effect of, 20 humic acid in, observed by Sprengel, 13 in the Grand Duchy of Hesse, 12 (loot-uote) loss of water by compretsing, 14 marsh of Montoire in France, 12 methods of cutting and preparing, iu Ger- many, Ireland, and Holland, 13 miscroccopical character of, 36 moulded from Griesheim, weights of, 18 nitrogen in, by Kane & Sullivan, 20 observations by Karsten, Bonalds, Kane and Sullivan, and Bainbridge, 14 ■older, described, 12 or turf, natural process of formation, 11 plants entering into composition of, 11 process of Williams at Cappoge, deecribi d, 14 producer gas from, 279-281 recent, described, 12 recent and older, comparative weight of a cubic foot, 12 relaiive value for heating, 361 resins in, observed by Mulder, 13 Kussian, analyses of, by VoskreHBensky,2o section on, 11-21 South American, composition of, 12 southern limits of, 12 specific gravity and density of, by Sir II. Kane, II by Sir R. Kane and Dr. Sullivan, 19 value of, dependent on dryness and density. 13 vegetable and animal remains preserved in, II water in, 14 weight of ash in a cubic foot found by Kar- marsch, 19 P^clet's comparison of the conductivities of iron and clay, 405 (foot-note) examination uf exit gases, 434 experiments on forced combustion, 384, 385 investigations of emission of heat by dif- ferent substances, 405 observations on vitiation of air, 493 Penny (Dr.), analyses of coal by, 741, 742 Percentages of ammonia, charcoal, tar, water, &c., from peat distillation, 206-208 of charcoal obtained from various lignites, 119 of water expelled by heat from air-dried wood, 5 in fresh cut woods, 3 Percy, analyses of coal by, 755-759 remarks on disposable hydrogen in coals, 123 on proximate constitution of coal, 709 Percy and Frankland on flame Inminosity, 371 Pdriss^'s (Sylvain) analyses of Ponsard producer gas, 281 Perkins' hot water system, 486, 487 Permeability of iron w hen hot to carbonic oxide, 404 Pernolet's coke ovens for recovery of bye-pro- ducts, 180-182 Philippart's account of processes for desulphuri- zation, 123 experiments on desulphurization, 123 Phillips' (J. A.) analyses of ash of coals, 52 Phillips' producer gas, analyses of, 283 Physical and chemical laws of heat production, important, i characters of coke, methods of determining, 149-152 properties of American cokes, by Fulton, 199 Pieler lamp, 72 Pierce's (Dr. H. M., of Elk Rapids) experimtnts on charcoal burning, 106 Piston or jigging machines for coal washing, 125 Pistorius's improvements on DOrn's still, 597 Pitch, distillation of, 618, 619 Plans of gas-firing applied to steam boilers, 539- 582 Plants from which peat is formed, 11 of the coal measures, 22 Player's anthracite feeder, 534 Playfair (Dr. Lyonl and Sir H. de la Beclie's reports, 702 Plus-pressure furnace, 655 Ponsard producer gus, analyses of, 281 Ponsard's furnace, 687, 688 superheated gazogene, 688 Porcelain kiln, 625 Porosity and specific gravity of coke, 145-160 Pottery-muffle, gas-fired, 628 Powdered fuel, furnaces for, 664 value of, 364, 365 Practical effect of fuel, 692-732 value of coals, tests of, 711 Preparation of cbarbon roux, methods of, iii of coke, general remarks on, 144, 145 of moulded charcoal, 112-114 Pressure, influence of, on luminosity of flames, 372 Pressures of escaping fire-damp, 68 Prevention of smoke, 373 Price's hot-water stove, 485, 486 retoit furnace, 685 Prideaux's automatic tire doors. 521 Princep's pyrometer, 339 796 INDEX. Frinciples, general, of distillatiou, 595 , of charcoal burning, 96, 97 of coal-washing process, 772 of combustion under pressure, 388, 389 of Coquillon'8 and Maurice's fire-damp indi- cator, 73 of forced draught, Miaary's examination of, 385, 386 of hot blast, 470-478 Process of burning charcoal in mounds, 93, 94 of burning in heaps or piles, 95 Processes for making artificial or patent fuel, 208-226 Proctor's mechanical stoker, 533 Producers, g^as, 250-275 Production, annual, and distribution of coal, 45 Products obtained from peat distillation, 206, 207, 208 of destructive distillation of coal, 120, I2i Progressive change in composition from woody fibre to anthracite, 58, 59 Propagation of fiame, 368-370 Properties of wood charcoal, 107, 108 Property of coking in various coals, 122 Proportions of Bunsen mixers, 433 Prussia, investigations on fire-damp and coal- dust, 71-82 Prussian Commissionj investigations on coal-dust, 80-82 Puddling by gas, Howson's, 674-676 Puddling furnaces, fuel consumption in, 657, 658 heat producrlon and utilization iu, 659, 660 Pyrometer, Amagat, 343 Berthelot, 346 Boulier Brothers, 343 Bystrom, 344 Carnelley and Burton, 341, 342 Daniell, 340 Deville and Troost, 340 Ducomet, 341 Frew, 347 Gauutlett, 342 Kahl, 347 Murrie, 347 Priucep, 339 Aegnault, 340 Saintignoo, 343 Schaffer and Budenberg, 347 Siemens, 343, 344 Trampler, 342 Wedgwood, 339 Weinbold, 344-346 Wilson (J.), 347 Pyrometers, 339-347 for hot blast, 347 Pyrometrical heating effect of carbonic oxide, 359 of coal, 354 of coke, 354 of furnace gases, 354 of lignite, 353, 354 of peat, 353 of peat charcoal, 354 of producer gasts, 354 of wood, 353 of wood charcoal, 354 heating effects according to Bunsen, 359 heating power of fuel, calculation for, 347- 352 R Kadcliffe's furnane, 689, 690 KaUiatiou, heating by, Mr. ff. Siemens' theory, 681-684 Hadiation, heat lost by, discovered by Don- kin's test, 721 JlaiIwa>B, use of lignite on, 28 Hankiue and Macadam, report on dust explosion at Glasgow, 77 liaukliie's examination of theoretical efficiency of liquid fuel, 294, 295 formulae for chimney draught, 382 Rapidity of ignition favoured by hydrogen, 2 Rate of heat transmission in boilers, 502 of ignition and inflammation of gaseous mixtures, 369, 370 of melting in Riley's gas cupolas, 678 Kates of combustion in various boilers, 504 Kecent peat, general description, 12 Kecovery of bye-products in coking, early attempts, 178-180 Red charcoal, 110-112 ush in, III average composition of, 112 water in, iii yield of, III Recce's process for distillation of peat, 203-208 Reflection and polarization of light from flame surfaces, 371 (toot-note) Regenerators, 668-670 continuous, of fire-brick, 668 of meta), 668 efficiency of, 669 for boiler firing by gas, 692 kinds of, in use, 668 reversing, loss of heat in, 669, 670 of firebrick, 668 surface of, required, 669 Siemens' reversing, 668 Regnault, analyses by, 743-746 Regnault's analyses of coal to determine propor- tion of hydrogen, 122 calorimeter, 334 observations on the relation of carbon in coal to coke, 142 pyrometer, 340 Regnault and Mulder, analyses of peat by, 19 Reinsch's analyses of ash of brown coal, 25, 26 Relation between composition and value of coals, 706 between hardness of wood and specific gravity, 5 of carbon in coal to coal produced, 141-143 of hydrogen to oxygen in various caking coals, 122 of surface to temperatures in boiler firing. 537 Relative densities of some gases and vapours, 372 heating value of substances compared with carbon, 334 value as fuel dependent on proportions of elements, 2 value of fuel, 332 Ren^ Duvoir's stoves, 440, 441 Renwick, analyses of coal by, j<^ Requirements of perfect combustion, 373 Resins in peat, 13 Results obtained with liquid fuel, 316-327 of American trials of coats, 712 of charring by methods of Karsten, Stolze, and Winkler, 89 of Darby's trials of gas firing for boilei-". 556-561 of experiments on the value of flues, 506 of gas firing (Fichet's) applied to f-team boilers, S46-550 of working Uadchfle's furnace, 690 I with Beaufuuie's system, 541 INDEX. 797 Results with Boutifeny's boiler, 583 with Cornish boilers gasi fired, 365, 566 with gas-fired boilers ac Gliifguw, 580-381 with Haupt's system, 534-556 with Lancashire boilers gas fired, 556-564 with Welsh and Scotch steam coals, 704 Retorts, Halliday's close, for sawdust, tan, &c., 6o3 Reverberatory ftirnace, 652 Reversing regenerators, 668 Richardson, analyses by, 733, 765, 766 Uicliardsjn'a furnace for silver residuum?, 651, 65"2 ore-hearth for lead ore, 637 Richter, analyses of coal by, 748 Riley's apparatus for liquid fuel, 315 Riley's (James) gas cupola furnaces, (yj"]^ 678 Rillieux system of evaporation, 590 Rittinger's (P. von) investigation of velocity of fall in water, 772, 773 " Spitzkosten," 776 Rivot, analyses of coal by, 765 Roberts- Austen's (W. C.) report on exit gases, 433 Robin, analyses of coal by, 742 Rogers, analyses by, 752-759 Rogers's system of drying and charring peat, 117, X18 Ronald's analyses of ash of coals, 52 of ash of peat, 15 of Irish peat, 20 observations on water in peat, 14 Roscher's results with air-dried lignite, 119 Rossi, analyses of coal by, 764 Rowan's (D., & Sou) gas-fired boilers, 575-582 Rowan (F. J.), method of estimating calorific value proposed by, 709 Rowan's (F. J.) gas producer, 2 Rowan's (Thomas) method of preventing spon- taneous ignition of coal, 83 process for desulpburization, 124 Royal Agricultural Society's trials of boilers, 729 Royal Commission on Accidents in Mines, ex- periments on gases, 70 report on coal-dust, 78-80 Royal Commissioners' experiments with safety lamps, 70 Rumford's experiments on specific gravity of wood, 6 open fire-place, 390 results from heating air-dried woods, 5 from heating wood, 89 on heating power of diflerent woods, 333 Russia, analyses of fuel from, 769 development of oU production in, 298, 299 Russian and American natural oils compared, 299 Russian peat, analyses of, by Voskressensky, 20 trials of Saghalien coal, 716 s Safety lamp indications of proportions of fire- damp, 70, 71, 72 Safety lamps, experiments with, 69-72 Saghalien coal, Russian trials 01,716 St. Bede chemical furnace, 656, 657 St. Gobain analysis of Siemens' producer gas, 280 St. Rollox, boiler at, arranged for smoke preven- tion, 514 Saintignon's pyrometer, 343 Salt-cake furnace, Jones and "Walsh's, 653, 634 old-fashioned hand, 654 worked by gras, 653, 654 Sap of diflerent kiudsof wood, contains diflferent substances, 3 of wood, constituents of, 3 Sardinia, analysis of coal from, 764 Saussure, analyses of coal by, 759 Saussufe's, De, determinations of gases ab- sorbed by charcoal, 108 Sauvages, analyses by, 745, 769 Sawdust, retorts for distilling, 60S Saxony, analyses of coal from, '-63 SchafFer and Budenberg's pyrometer, 347 Schafhautl, analyses by, 738, 742 ' analyses of gases from Ysialyfera by, 237 Scheerer and Langberg's analyses of gases Jiom Barum, 234 Seheeter's experiments on desulphurization by steam, 123 view of proportion of charcoal consumed in charcoal-burning, 98 Schellhammer's (H.) investi&ration of influence of pressure on blast, 477, 478 Scheui'er-Kestner's examination of waste gases, 434 experiments, 717-721 Schilling and Bunte's plan of heating gas retorts, 613-610 SchSdler and Petersen's analyses of dried woods^ 10 Schonheyder's gas stove, 422, 423 Schrotter, analyses by, 767 Schiibler's analyses of ash of peat, 15 Schiibler and Neufler's estimates of amount of water in wood felled in January and in April, 3 Schwackliofer's calorimeter, 335 Schwartz charcoal kilns, 103 Scotch and other coals, economic value of, 701 and Welsh steam coals compared, 703 blast fumades, 638 coals, analyses of, 53, 56 Scotland, analyses of bituminous coals of, 733, 740-742 Selwyn's apparatus for liquid fuel, 320 Senez, analyses of coal by, 746 Sentis, analyses of coal by, 747 Seraing, Ebelmen's analyses of gases from, 236 Shales compared with coking coal, 34 composition of, compared with TorbanehiU coal, 34 Sheppard's coal-washing machine, 135, 137, 138 Siemens' breeze oven, 176, 177 circiUar produci-r, 270 coke gas fire, 399 furnaces, modifications in the construction of, 680-683 gas furnace, the, 679, 681 gas producer, 254 modified furnaces, 682 plan as modified at Glasgow g^works, 617 producer gas, an lyses of, 280-283 pyrometer, 343, 344, regenerative system applied to gas retorts, 610, 611 reversing regenerators, 668, 669 loss of heat in, 669 size and surface of, 669 Siemens' (F.) theory of heating by radiation, 681-684 Silesia and Westphalia, analyses of coal from, 765 Silesian coke oven, 164 open kiln for coking small coal, 165 798 INDEX. Silliman, analyses of coal by, 755 Silver residuums, furnace lor treating, 651, 652 Simon-Carved' coke ovens, 186-188 Size of blast furnace iufluences working, 641, 642 Sizes and construction of charcoal beaps, 94, 95 Slow method of charring compared with rapid, 88, 89 Sluices for coal- washing, 126, 127 Smith's (A.& W., & Co.) triple-effSt apparatus, S9I Smith-Casson's furnace, 685 Smoke, formation of, shown by Berthelot, 718 shown by Deville, 718 prevention of, 373, 511 Howard & Co.'s plan, 513 Wait's plan, 513 Wye Williams' furnace for, 512 Snelus' calculation of furnace efficiency, 669, 6;o Soda-lime as an absorbent for gases from com- bustion, 719 Solids and gases in blast fUmace, relations between, 475 Soret's experiments on the reflection of light from flames, 371 (foot-note) Sources of heat, knowledge of, important, i of supply of oil for fuel, 299, 300 South American peat, composition of, 12 Specific gravities of gases composing fire-damp, 69 Specific gravity and density of peat, 18, 19 of brown coal, 27 of charcoal, 109 of coal, 50, 51 of different kinds of wood, table of, 6 of wood, its relation to hardness, 5 modes of ascertaining, 6 Specific heat, mean, of wrought iron, 345, 346 Spent tan used as fuel, 330 Spitzk'asten, Bittinger's, 776 Splint or hard coal, general account of, 46 Spontaneous ignition of charcoal dust, no of coal, 83 Spoor's stove, 407 Spcengel, humic acid-observed in peat by, 13 Square coke ovens formerly used, 163 Staffordshire blast fuma.-es, 638 State of division of fuel, effect of, 364, 365 Stationary meilers, 99 Stead's analyses of 'Wilson's producer gas, 282, 283 Steam blast for producing chimney draught, 383 coal, important features of, 710 lieated, used in making charbon roux, in heaters, 485 jacket evaporators, heating effect of surface of, 587 pipe coil, heating effect of surface of, 588 superheated, used by Vignoles for distill- ing peat, 609 used for drying wood, 5 used for making peat charcoal, 117 used for producing wood charcoal, 105 Steel making, use of lignite in, 28 melting furnaces of M. Sudr^, 660, 661 Stein's remarks on the ultimate composition of caking coals, 123 Sterry Hunt's method of determining porosity, 151 Stevenson's plan of healing gas retorts, 617 Stewart's rapid cupola, 644 Still, Coffey's, 600-606 Derosne's, 598, 599 Dorn's, 597, 598 Still, old pot, used for whisky, 596, 597 simplest form of, 596 Stokers, mechanical, 515-535 Staking, hand and machine compared, 534 Stolze's amounts of tar from different woods, 102 method of charring wood compared with others, 89 Stones* patent process for compressed peat, 116 Stoneware kiln, 626 Storer and Lewis's estimates of occluded gas in coke, 143 Stoves, 403-432 Adams' gas, 417, 418 gas cooking, 429, 430 American, 407, 408 Amott's, 406 Bissett's hot-air, 450 Bond's (Dr.) gas, 420, 421 circular, for hot blast, 460, 461 Constantino's, 444-448 Continental brick, 410 Cowper's regenerative hot-blast, 463-466 Dnnnachie's brick, 412, 413 early forms of hot-blast, 453-455 fire-brick, 410 Fletcher's gas, 418, 419 gas cooking, 427, 428 gas, 413-432 gas, comparative efficiency of, 423-425 gas cooking, 426-432 efficiency of, 431, 432 heating surface of, 404, 405 hot-air, 437-450 hot-blast, 450-478 Main's gas cooking, 426 Massicks and Crooke's hot blast, 468-470 materials for the construction of, 403, 404 metal, for solid fuel, 409-411 Napier's, 411 oval forms for hot blast, 462 Een^ DuToir's, 440, 441 Schonheyder's gas, 422, 423 Spoor'8, 407 Talabot's, 442 Whitwell's hot blast, 466-468 Wright's gas, 420 gas cooking, 426-429 Strata of different coal-fields, 42, 43 Stratification of coal, different irom that of wood, 40 evidence of fossil tree stems, 40 Straw used as fuel, 330, 331 Sudr^'s reverberatory furnaces, 661 Sulphur in cannel and other coal, 49 in coal, 52, 124 Superheated gazogene, gain of heat by, 688 Supply of liquid fbel, sources of, 299, 300 Supposed marine origin of cannel coal vegetable remains, 49 Surface evaporation of weak liquors, 586 evaporator with straight steam pipes, 589 Surfaces, efi'ects of, on flame, 682-'684 Sutherland's gas blowpipe furnaces, 674 gas producers, 268-270 Sweden, Schwartz and other charcoal kilns em- ployed there, 103, 104 yield of charcoal from meilers, 105 Swedish gas furnaces, early, using blowpipe, 670- 674 Swindell's furnace, 685 Sylvester's open fire-places, 391-394 INDEX. 799 T Table of absolute heating effects of carbonic oxide, mai'dh gas, aiid oleliant gas, 356 of ages of wood at perfect grov^th and when fit for charring, 90 of amount of a^h iu charcoal, 109 in varieties of brown coal, 25 of analyses and calorific power of various coals, 708 and specific gravity of anthracites, 57 of ash of American anthracites, 58 of brown coal, 26, 27 of coals used in American trials, 713, 714 of cokes, 143 of fire-damp, 61, 69 of gas (Thomas's) yielded by coal at 100" C., 86 of gases from coke ovens, 201 of Irish peat by Kane and Sullivan, 20 of natural gas, 290 of oil gas, 329 of peat by Kegnault and Mulder, 19 of Russian peat by Voskressensky and Irish by Konalds, 20 of Scotch and Welsh steam coals, 703 of Siemens' producer gas, 291 of specimens of patent fuel, 212 of the ash of varieties of coal, 32 of various cokes by Sir Lowthian Bell, 193 of various coals and observed calorific power, 720 of waste gases in Bramwell's trials, 731 of analysis of expenditure of fuel in kilns, of fire-damp, 69 of waste gases from Selwyn's boiler, 320 of annual distribution of British coal from I'echar, 45 of ash in 100 parts of wood, by Berthier and Karsten, 9 in different woods by Chevandier, per- centage of, 9 in peat, percentage of, 14, 15 of average composition of coals from differ- ent localities, 56 composition of foreign coals, 56 results of tests of gas-burners, 414, 415 time in which wood is fit for felling, 5 of Berthelot's corrections of Bunsen's re- sults, 368 of boiling point of water at diflEerent pres- sures, 590 of Bunsen's results on ignition of gases, 397 of calorific power and specific beat of five varieties of pure carbon, 707 of carbon percentag-e compared with evapo- ration, 716 of character and efficiency of American coals, 696, 697 of charcoal yielded by various woods, 105 from lignites, percentages ol, 119 of coal raised in Britain, total quantities of, 1840-1885, 45 of coke and bye-products obtained with Jameson ovens, 185 and fixed carbon in Continental coals by Karsten, 141, 142 percentage compared with evaporation, 715 I Table of coniparative experiments on evaporative effect ol coal, wood, and peat by W. Anderson, results of, 21 results of hand and mechanical stoking, 534 results with hand and gas firing pt Brieg, 556 results with Siemens and Fonsard fur- naces, 689 of comparison of foreign coke with cliar^ coal, 197 of Russian and American oils, 299 of composition of gases occluded iu coal, 84. 8s of shales, 34 of Denny's tests of efficiency of heating apparatus, 423 of destructive distillation of coal, products of, 121 of distribution of heat in furnaces, 662 of heat in Siemens' furnace, 670 of elementary composition of bituminous coal and anthracite, 53 of evaporative perfonnance of American coals, 727 of Newcastle and Welsh coals, 728 of evaporative results with Lancashire and Cheshire coals, 727 with land boilers using Hindley Yard coal, 724, 725 of evaporative tests of Scotch and Welsh coals, 704 of explosive proportions of air and fire- damp, 71 of general properties of moulded lignite, 28 of heat and volume of blast equivalent to carbon, 477 distribution in Fonsard's system of fur- naces, 688 value of specimens of oil gas, 330 of heating effects of combustibles (from Sheerer), 353, 354 power of coal and coke in blast furnace, 239 suri'ace and cost of various hot-blast stoves, 471 values of different fuels (I. to VIII.), 360-363 of hydrogen and oxygen in caking and other coals, relations of, 122 of hygrometric moisture in resinous and non -resinous woods, 4 of limiting velocities of particles of differ- ent sizes in coal washing, 775 of litharge test for heat efiSciency as com- pared with evaporation, 715 of mean composition of average samples of Derbyshire coals, 55 of average samples of Lancashire coals, 55 of average samples of Newcastle coals^ 54j55 of average samples of Scotch and other coals, 56 of average samples of Welsh coals, 53, 54 of mean specific heat of wrought iron, 345, 346 of melting-points, 341 of observations on temperatures of flame, 366 of oil production in America, statistics of, 293 of percentage of charcoal from quick aud slow charring, 89 of coal soluble in naphtha, 31 of water in different kinds of wood, 3 8oo INDEX. Tdble of physical properties of Americiiu cokes by J. Fulton, 199 of properties of Llangennech cojil, 497 of proportions of Bunseu mixers, 433 of land boilers, 504 of pyrometrical heating effects given by Bunsen, 359 powers (calculated), 351 of relative coal area, production and value in 1845, 45 densities of gases and vapours, 372 heating surface and fuel consumption in locomotive boilers, 726 magnitude and coal area of different countries, 44 of results from Radcliffe's furnace, 690 of Agricultural Society's tests of boilers, 729 of American trials of coals, 712 of chemical tests of gases from stoves, 435-438 of expeiiments with coke exposed to carbonic acid, 196 of experiments with coke exposed to high temperature, 195 ; of gas-firing boilers at Cherbourg, 541 j of gas-firing Lancashire boilers, 564 1 of hand firing verstia gas firing, 565, 566 ; of Hessian experiments on boilers, 506 ! of Mulhouse Society's tests of boilers, > 722 of the distillation of various coals, 35 of tests of Bray's burner, 416 with cold and hot blast (1829-33), 45^ with liquid fuel (Selwyn's plan), 320 with liquid fuels (Thvtaite's plan), 318, 319 of specific gravities of varieties of coal, 31 of specific gravity, analyses and method of manufacture of American coke, j6o and ash of American anthracites, 51 of, and ash in, various coals, 50 of charcoal, 109 of ioreign woods by Marcus Bull, 7 of wood by Hartig, Wernek, Winkler, and Mushenbroek, 6 of woods by Karmarsch, 7 of summary of heating efiiects, 355 of tost of gas-heating stoves, Glasgow Exhibition, 1880, 424, 425 of tests of gas-cooking stoves, 431 by D. K. Clark (1882-83), 432 of values of co-efiicient in of radiation from pipes, 482 of velocity of fall of difi'erent minerals in water, 773 of water expelled from various- woods at different temperatures, 5 of weight of wood in given space by Marcus Bull, 8 of wood ashes, composition of certain, by BOttiiiger, 9 of Wright's experiments on velocity of ignition, 370 showing nature of the ash of cannel coal and shales, 48 Tables of analyses of American coal and coke, 153-159 of ash of brown coal, 25, 26 of ash of coals, 52 of ash of peat, 15, 16 of British cannel coals, 47, 48 of coals, lignites, turf, wood, coal ashes, peat ashes, coke, shale from various countries In the world, 733-769 Tables of analyses of producer gases, 278-28^ of woods, 10 of analysis of splint coal and gaftus from blast furnace using it, 240, 241 of blast furnace gases, composition of, 233- 237, 248-250 of charcoal produce estimated by volume, 106, 107 of coal-dust explosions, results of, 80-82 of coke and charcoal in COg, air, and hydro- gen, results of heating, 198 of evaporative values of wood and other combustibles, 333. 334 of M. Fichet's results of gas firing applied to boilers, 547-550 of fractionation of tars from coke ovens and blast fhrnaces, 202, 203 of heat value of natural gas, calculation of, 291 of oilti, 295-297 of porosity aud specific gravity of coke, Dewey's results of examination of, 153-159 of products obtained by the distillation of peat, 206-208 of results of Admiralty investigation of eco- nomic value of different 00813,698-701 of Darby's trials of gas firing, 558-561 of use of liquid fuel on Grazi and Tsaritsin Railway, 321-326 of water and gases absorbed by charcoal, 108 of weight of furnace gases and heat evolved aud appropriated in blast furnace, 242, 243 showing progressive change in composition from woody fibres to anthracite, 58,59 Talabot's hot-air stove, 442 Tan, spent, used as fuel, 330 Tar and ammonia recovery in coking, 178-192 amounts of, from different woods, 102 from coke ovens and blast furnaces, 202, 203 recovery of, from charring wood, loi. 102 Taylor (R. C ), analyses of coal by, 733-^59 Technical applications of coal, 34 Temperature, elevated, or power derived from it, required in all manufacturing, che- mical, and metallurgical processes, i in boiler firing and relation to surface. 537 necessary for ignition of fire-damp, 61 observed in Otto's coke ovens, 192 of coking affects produce, 140 of flame, 366-368 range of, available in triple-eifSt apparatus, 590 Temperatures ascertained by Princep, 339 of combustion observed in steam-boiler work, 496-501 obtained by Bunsen, 359 of ignition of gaseous mixture!*, 75 Tervet's gas producer, 273 Tessie du Motay's gas producer, 265 Tests of efficiency of gas cooking siuves, 431, 432 of gas burners, 414, 415 Theory of coal formation, 22 of heat, 331 Thermal value of liquid fuel, 328-330 of natural gas, 290-292 of oil-gas, 329, 330 of oils, 297, 318 of producer gas, 283 of water-gas, 285 Thomas aud Laurent, use of steam in making charcoal, in Thomas's (J. W.) experiments on coal, 86 INDEX. 8oi Thompson's calorimeter, 334, 335 Thomson, analysis of coal • y, 733, 741 Thomson's suggestion for mechanical heating, 494 Thurston's investigation of performance of spent tan, 330 Thwaite's apparatus for liquid fuel, 317 gas producer, 273-275 Tidy's (C. Meymott) statement of nitrogen in coal, 52 Time required for charcDjl lu n ig iu heaps, 95 for charcoal burning m mounds, 94 to attain maximum dryness in various viroods, 4 Townsend's travelling; grate, 520 Trampler's pyrometer, 342 Transfer of heat through boiler-plates, 501 Transmission of heat, laws of, 495 rate of, in boilers, 502 Trees, parts of, called " wood " as fuel, 2 Triple-eflet apparatus, 590, 591 Troilius's (Magnus) analyses of producer gases, 283 Troost, analyses by, 752 Turf from France, analyses of, 769 from Germany, analyses of, 768, 769 Turkey, analyses of coals iVom, 765 Turkish bath at Arlino^ton Baths, Glasgow, hot air for, 449 at Llandudno Hydropathic, hot air for, 449 at Victoria Baths, Glasgow, hot air for, 450 Turkish baths, stoyes for, 449,450 Tuscany, analysis of coal from, 764 Tyndall and Firankland's observations on flames, 372 IT Ultimate composition of caking coals, 123 Under-grate blowers for producing draught, 384 Uninflammable dust, expl<^ions with, 79 Ure, analyses of coal by, 733-741 Urquhart's apparatus for liquid fuel, 312, 313 Vacuum pan, 589 range of, in the Hillieux system, 590 Valon's plan for heating gas retorts, 614 Value and composition of coals, relation be- tween, 706 Value, comparative, of litharge test, 715 Value of coals measured by carbon contained, 711-716 by hydrogen contained, 711-713 by oxyg-en consumed, 711-713 of fuel diminished by incombustible ash, 2 of peat dependent on dryness and density, 13 relative, of substances as fuel dependent on proportions of elements, 2 Vanuxem (L.), analysed of coal by, 758, 759 Vaporization, 503 application of fuel to, 494 how it takes place in the Yaryan apparatus, 592 Variation between experhnent and calculation of caloriflc value, 708 of temperature in multiple effect evapora- tion, 590, 591 Varieties of coal, general account of, 45, 46 Varin, analyses of coal by, 742-746 Varrentrapp's analysis of ash of brown coal, 26 Vaux, analyses of ash of coals by, 52 of coal by, 766 Veckerhagen, Bunsen's analyses of gas from;233 Vegetable origin of coal, 22 remains in coal, 38, 39 Velocity of flame propagation, 369, 370 of gases iu. chimneys, 378, 379 of hot gases from toilers, 503 Verity's gas fire, 402 Verpilleux and Vital, experiments on coa'-dust by, 76, 77 Vertical meiler, 92 Vicars' mechanical stokers, 523 Vicars' (T. & T.) mechanical ^toke^, ^$1, 532 Vienne and Pont I'Ev^ue, Ebelmen's analyses of gases from, 235 Vignoles' apparatus ior distilling peat by steam, 609 process for making peat charcoal, 117 Violette's experiments in drying wood by steam, 5 process for preparing charbon roux, iii Vital, experiments on coal-dust by, 76, yy Vitiation of air by respiration, &c., 493 Vitriol, evaporation of, in open pans, 584 Voisin's cupola, 648, 649 Volatile to non-volatile matter, relation of, in coals, 34 Voskressensky, analyses by, 747, 769 analysis of Russian peat by, 20 w Wagon-shaped boiler setting, 515 Wales, North, analyses of coals of, 739, 740 South, analyses of coals of, 734-738 Wallace's (W.) examination of Longrigg coal, 703 Walz, analyses by, 768 Warlich's patent fuel, 213, 214 Warming, relative values of diflTerent fuels for,695 Wartha's (V.) experiments on flames, 373 Washing coal, general principles of, 771 machines for coal, 125-140 Washington Navy Yard, evaporative results ob- tained at, 727 Waste gases, soda lime best absorbent of, 719 used in calculating volume of air used, 718, 719 Water absorbed by wood charcoal, 108 amount of, expelled by heat from air-dried wood, 5 amount of, in different woods at difEerent times, 3 and gases absorbed by coke, 143 and steam, heating by, 478-503 boiling-point altered by diminution of pres- sure,. 590 in brown coal, 24 in charbon roux, 11 1 in peat, 14 in wood, influence of, 3 Water-gas, analyses of, 285 producers, 262 Watson Smith's examination of tar from coke ovens, &c., 202, 203 Watt's plan for smoke prevention, 513 Wealth of Britain derived from fuel, i Weathering of coal, 83 Wedding's (H.) fbrnace at Berlin, 673 Wedgwood's pyrometer, 339 Weight, comparative, of a ajhic foot of recent and old peat, 12 3 F 802 INDEX. Weight of ash in a cubic foot of peat, by Kar- marsch, 19 of brown coal in a cubic foot, 27 of charcoal increased by arrcBtlng charring process, no of coal in relation to its bulk, 696-705, of wood in relation to its mass, 8 Weinhold's pyrometer, 344-346 Welsh and Newcastle coalv, evaporative results from, 728 and Scutch steam coals compared, 703 coals, analyses of, 53, 54, 56 economic values of, 698 furnace plan of collecting gaBcs, 229 Welter's law, supported by Bethke and Ltirmann, 356-358 theory as to heating effect, 335, 336 Werlisch 011 absorption of water by charcoal, 108 Wernek's estimate of loss by immerfiion of wood in water, 8 Weschnaekoff's carboleine as fuel, 365 West Cumberland blast furnace, 640 Whitw ell's hot-blast stove, 466-468 Williams' process for peat at Cappoge described, 14 Wilson and Smith's mechanical stoker, 523 Wilson's gan cupola design, 677 gas producers, 2^3-265 plan ot heating gas retorts, 61B, 6T9 producer gas, analyses of, 282, 283 Wilson's (E, B.) furnaces, 685 Wilson's (J.) pyromet^ir, 347 Winkler, observations by, on moisture in wood, 5 Winkler's estimates of ash in cliarcoal, 109 method of charring wood compared with others, 88, 89 Without flame, varieties of fuel which bum, 2 Wittenstrbm's apparatus for liquid fuel, 313- 315 Wood, air-dried, how prepared, 4 amount of ash in, 8 analy: es of different kinds, by Schodler and Petersen, and Chevandier, 10 ash in, determinations by Berthler, Karsten, Chevandier, and Bottinger, 9 ash of, analyses of composition of, 9 general character, 8 amount of water in, at different periods, 3 importance of, 3 chambers for drying, 620, 621 charcoal, properties of, 107, 108 section on, 88-115 constituents of sap of, 3 distillation of, for vinegar, apparatus lor, 607, 608 dried, different kinds contain same Cle- men' s, 3 drvjng of, observations by Af Uhr. 94 effects of different temperatures on, 5 elementary composition of, 10 for fuel, age when fit for felling, 5 Wood, freph cut, percentage of water in, 3 general classification of, into hard and soft, 5 composition of, 3 result of analyses of air- and kiln-dried kinds, II heating effect of, 692, 693 hygroscopic state of, 4 imperfectly charred, qualities of, no, in kinds of, differences between, 3 loss in bulk during charring, 96 loss of weight by immersion in water, 8 mass of, in relation to its vt eight, 8 maximum etate of dryness, when attained, 4 parts of trees thus classed for fuel, 2 pioper a^e for charring, 90 relation between specific gravity and hard- ness, 5 relative value for heating, 360 section on, 2-1 1 specific gravity of, Karmarsch's detirniiu