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MINE GASES AND EXPLOSIONS

TEXT-BOOK FOR SCHOOLS AND COLLEGES

AND FOR

GENERAL REFERENCE

J. T. BEARD, C.E., E.M.

Principal School of Mines (Coal-Mining Division), International Correspondence

Schools: Professor of Chemistry and Mining, School of the Lackawanna —

College Department : Associate Editor Mines and Minerals : Member

North of England Institute of Mining and Mechanical Engineers ;

American Institute Mining Engineers : The National C*#-

graphic Society: Scranton Engineers Club.

FIRST EDITION ^/

FIRST THOUSAND

^ / \ ^

y/A

NEW YORK

JOHN WILEY &

SONS

London: CHAPMAN & HALL, Limited

1908.

Try

J. T. BEARD

WiXtbttt Snimmanib anli CHomttang

To HiB Friend

Mt. games agt^octf), M.IB.

This Book is Dedicated

With Many Pleasant Recollections,

By The Author

PREFACE

Since the publication of the author's first book on the
Ventilation of Mines in 1894, he has written numerous
short articles, which have appeared from time to time,
bearing on the general subject of Ventilation, including,
besides the treatment of the theory and practice of all
classes of ventilating machinery and appliances, a detailed
study of mine gases, their occurrence, properties, and
detection, together with the allied subjects of mine explo-
sions, safety lamps, illuminating oils, etc.

Several of these articles were published in pamphlet
form and distributed. The increasing demand for more
copies of these little pamphlets and numerous requests
that the subject matter they contained be printed in book
form has suggested the expediency of revising the former
book, the first edition being now exhausted. In doing this
it became apparent that the general subject should be
divided and treated under two heads, so as to form two
separate books, one entitled Mine Gases and Explosions
and the other Ventilation of Mines.

The aim in each of these books is to present a practical
subject in a practical way, so that the text will breathe
forth the very atmosphere of the mine. The elements of
physics and chemistry are explained, so far as they relate

iii

IV PREFACE

to the subject of air and gases, in such a manner as to
make clear the behavior of the latter in the mine. Suffi-
cient of the history of the subject is given to show the
thread of the development in all points of interest, but
history is not given for the sake of history alone.

One of the chief aims has been to establish and use
throughout the entire text, and in compiling the tables, a
set of constants and values that are reliable and used by
the best authorities, and that at the same time correspond.
The author hopes that this feature of these books, com-
bined with their practical setting, will commend them to
technical students desirous of obtaining a working knowl-
edge of the subject of Ventilation.

The author acknowledges with much pleasure and with
deep gratitude the valuable assistance given him by Mr.
James Ashworth, Old Colwyn, England, who generously
contributed a number of photographs of safety lamps,
together with much valuable information on this and
other portions of the subject; also the assistance of Mr. J.
J. Clark, Dean of Faculty, International. Correspondence
Schools, Scranton, Pa., and Dr. S. W. Stratton, Director
of the Bureau of Standards, Washington, D. C, together
with a large number of mine inspectors, superintendents,
foremen, and fire bosses, who have at all times lent their
aid and afforded the author opportunities for investigations
that he could not otherwise have made. To all of these
he extends heartfelt thanks.

J. T. Beard.

Scranton, Pa., May 1, 1907.

CONTENTS

N.B. — ^The numbers in the text refer to the articles where they are to be found.

PAGE

Preface -------_------__ iH

INTRODUCTION -.----- 1

Natural Conditions, 1. Natural Laws, 2. Occurrence
of Mine Gases, 3. Important Mine Gases, 4.

CHAPTER I

The Chemistry and Physics of Gases 4

Chemistry, 5; Physics, 6.
Matter - - 4

Matter; Mass, Density, 7. State of Matter; Solid, Liquid,
Gaseous (Fluids), 8. Divisions of Matter; Atoms, Mole-
cules, Ions, Cations, Anion, 9. The Elements ; Elementary
Matter, Compound, Mechanical Mixture, Chemical Com-
pound, 10. Forces Inherent in Matter; Affinity, Attraction,
11. Gravitation, 12. Cohesion, Adhesion, 13. Mag-
netism, 14.

Properties of Matter --'------_-_-_ lo

Constitution of Matter; Atomic Theory, 15. Volume,
16. Mass, 17. Density, 18. Compressibility, 19. Elastic-
ity, 20. Viscosity, 21. Porosity, 22. Capillary Attrac-
tion. 23. Transpiration, Diffusion, Effusion, 24. Con-
ductivity, 25. Inertia, 26. Heat, 27. Weight, 28. Atomic
Weight, 29. Molecular Weight, 30. Atomic Volume,
Molecular Volume, Specific Volume ; Avogadro's Law, 31.

Specific Gravity - --- ___16

Specific Gravity, 32. Methods of Determining the
Specific Gravity of Solids, Liquids, and Gases, 33. Method
by a Balance, 34. Method by the Hydrometer; The
Nicholson or Fahrenheit Hydrometer ; The Baume Hydro-

vi CONTENTS

PAGE

meter, 35. Specific Gravities of Various Substances, 36.
Difference between Atomic Weight and Specific Gravity,
37. The Use of Specific Gravity; Rule; For Solids or
Liquids; For Gases, 38.
Chemical Reactions and Effects ----------25

Chemical Reaction, 39. S5mibols, 40. Chemical For-
mulas, 41. A Chemical Equation, 42. The Use of Chemical
Formulas and Equations, 43. Percentage Composition by
Weight, 44. Percentage Composition by Volume, 45.
Change of Volume Due to Chemical Reaction, 46. Calcula-
tion of Change of Volume, 47. Effect of Change of Volume,
48.

Examination Questions

Specific Gravity --------- 40

Chemistry 41

CHAPTER II
Heat and its Effects -- 42

Heat, 49. Temperature; Fahrenheit, Centigrade,
Reaumur Scales, 50. Sources of Heat, 51. Heat in
Matter, Change of State, 52. Transmission of Heat;
Radiation, Conduction, Convection, 53. Measurement of
Heat, Heat Units; British Thermal Unit, French Unit,
Calorie, Pound-calorie, 54. Mechanical Equivalent of
Heat, 55. Heat Capacity, Specific Heat, Constant Pres-
sure, Constant Volume, 56. Sensible Heat, Latent Heat, 57.
Evaporation, Boiling, 58. Expansions, 59. Absolute Zero,
Absolute Temperature, 60. Relation of the Absolute Tem-
perature and Volume of Air and Gases; Gay Lussac's or
Charles' Law, 61. Relation of the Absolute Temperature
and Pressure of Air and Gases, 62. Relation of the
Volume and Pressure of Air and Gases; Boyle's or
Mariotte's law, 63. Adiabatic Expansion and Compres-
sion of Air and Gases, 64.

Combustion --- ____-- 62

Supporter of Combustion, Spontaneous Combustion, 65.
Oxidation, Rusting, 66. Products of Combustion; Gaseous
Products, Residue of Ash, 67. Heat of Combustion, 68.
Temperature of Combustion ; Theoretical Flame Tempera-

CONTENTS vii

PAGE

ture, Flame Volume, 69. Calorific Power or Heating Value,
70. Comparison of Fuels; Dulong's Formula, 71.

Examination Questions
Heat 72

CHAPTER IH

The Atmosppere 74

The Atmosphere, 72. Composition of the Atmosphere ;
By Volume, By Weight, 73. Weight of Air, 74. Formulas ■
for Weight of Air, 75. Atmospheric Pressure, 76. The
Mercurial Barometer; Standard Readings, 77. The
Aneroid Barometer; The Altitude Scale, Mining Aneroid,
78. Use of the Barometer, 79. Atmospheric Pressure and
Barometric Readings at Different Elevations, 80. Effect
of Gravity on Barometric Pressure, 81. Measurement
of Pressures in Atmospheres, 82. Moisture in the Air;
Hygrometric Condition, Laws, Pressure (Tension) of Aque-
ous Vapor, 83. Weight of Moist Air, 84. Measurement of
the Moisture in the Air; Leslie's or Mason's Hygrometer,
The Hygrodeik, 85.

CHAPTER IV
The Common Mine Gases 99

Damps ; Chokedamp or Blackdamp, Whitedamp, Stink-
damp, Firedamp, Afterdamp, 86. Methane, Light Car-
bureted Hydrogen, Marsh Gas, 87. Firedamp, 88. Feeder
Gas, 89. Inflammable and Explosive Range of Methane,
90. Effect of Other Gases on Firedamp; defiant Gas,
Carbon Monoxide, Carbon Dioxide, Nitrogen, Coaldust, 91.
Carbon Monoxide, Carbonic Oxide; Blood Test, 92.
Poisonous Action and Effect of Carbon Monoxide, 93.
Carbon Dioxide, Carbonic Acid Gas, 94. Hydrogen Sul-
phide, Sulphureted Hydrogen, 95. Olefiant Gas, Ethyl-
ene, Ethene; Ethane, 96. Nitrous Oxide, 97. Nitrogen,
98. Oxygen, 99. Hydrogen, 100.
The Behavior of Mine Gases - --- 114

Laws that Govern the Motions of Gases, 101. Gravity
of Gases; Effect of Temperature, Accumulation of Gas,

viii CONTENTS

PAGE

Stratification of Gas, Removal of Gas, 'l02. Occlusion of
Gases; Singing of the Coal, Poundings, Knockings, Bumps,

103. Transpiration or Emission of Mine Gases; Effusion,

104. Rate of Transpiration; Laws, 105. Gas Pockets,
Feeders, Blowers, 106. Outbursts of Gas, 107. Diffusion
of Gases, 108. Rate of Diffusion ; Law, 109.

Mixtures of Gases and Air ------ 126

The Nature of Gases to Mix, Firedamp, 110. Flash-
damp; Calculations Pertaining to Flashdamp, Heavy
Flashdamp, Light Flashdamp, 111. Afterdamp, 112.

Mine Air 132

General Character of Mine Air, Percentage of Oxygen in
,Mine Air, 113. Gaseous Condition of Mine Air; A Non-
Gaseous Mine, A Gassy or Gaseous Mine, A Fiery Mine,
114. An Explosive Atmosphere, 115. An Extinctive
Atmosphere, 116. A Dangerous Atmosphere, 117. A
Fatal Atmosphere, 118.

CHAPTER V
Mine Explosions 146

Character of a Mine Explosion, 119. Inflammable Mine
Gases and Material, 120. Ignition of Gases; Pressure
Assists Ignition, 121. Temperature and Volume of Flame,
122. Heat Energy of Combustibles, 123. Spontaneous
Combustion, 124. Gob Fires, 125. Treatment of Gob
Fires, 126. Causes of the Ignition of Mine Gases, 127.
The Initiation of a Mine Explosion, 128. A Gas Explo-
sion, 129. A Dust Explosion, 130. History of Coal Dust
as a Theory, 131. The Coal Dust Theory, 132. The Per-
cussive Theory, 133. Character and Influence of Dust,
134. Phenomena of Mine Explosions, 135. Entering a
Mine After an Explosion, Rescue Work; Breathing Ap-
paratus, 136. Mine Hospitals, Refuge Stations, 137.
Record of Recent Disastrous Mine Explosions, 138,
Prevention of Mine Explosions, 139. Relation of Blasting
to Mine Explosions; Blown-out Shot, Windy Shot, Explo-
sives used , Flameless Powders, Water Cartridge, Detonat-
ing Explosives, Blasting in Gas, Electric Firing, Use of
Fuse, Squibs, Touch-paper, Heated Wire, Order of Firing,
Slowing the Fan, 140. Relation of Atmospheric Condi-

CONTENTS ix

PAGE

tions to Mine Explosions; Barometric Pressure, Tempera-
ture and Hygrometric Condition of the Mine Air, 141.
Earth Breathings; Periods of Danger, Periods of Fre-
quency of Mine Explosions, 142. Calculation of Initial
Pressure of a Gas Explosion, 143.

CHAPTER VI
Safety Lamps ----- 215

Early Practices, 144. The Steel Mill, 145. The First
Mine Safety Lamp, 146. What Constitutes a Safety
Lamp, 147. The Principle of the Safety Lamp, 148.
Safety Lamp Construction, 149. Conditions in the Lamp ;
Free Circulation of Air, Flaming, Explosions within the
Lamp, 150. Influence of Wire Gauze; Failure of the Lamp,
151. Testing Safety Lamps, 152.
Classification of Safety Lamps 227

Classification, 153. Lamps for Testing for Gas; Re-
quirements, Eloin Principle, 154. Lamps for General
Use, 155.
Types of Safety Lamps - - 233

Forecast, 156. The Davy Lamp; Fireboss Davy, Pocket
Davy, Davy-in-case — Tin-can Davy, Davy with Glass
Shield, Davy-jack, Jack Davy, Fire Tryer's — Gas Finder's
— Fireman's Davy, Scotch Davy, 157. The Stephenson or
"Geordie" Lamp, 158. The Clanny Lamp, 159. The
Evan Thomas No. 7; Cambrian Lamp, 160. The Bull's
Eye (Mauchline) Lamp,' 161. The Marsaut Lamp, 162.
The Gray Lamp; Gray Inlet Tubes, 163. The Ashworth
Lamp, 164. The Ashworth-Hepplewhite-Gray Lamp, 165.
The Beard Deputy Lamp; Sight Indication, 166. The
Mueseler Lamp; English Mueseler, Belgian Mueseler, 167.
Special Safety Lamps 262

Lamps Burning Special Oils, 168. The Pieler Lamp, 169.
The Chesneau Lamp, 170. The Stokes Alcohol Lamp,
171. The Ashworth Tester, 172. The Clowes Hydrogen
Lamp, 173. The Beard-Mackie Lamps, 174. The Wolf
Lamp, 175.
Locks for Safety Lamps 280

Design or Purpose of a Lock on a Safety Lamp, 176.
Requirements of Locks for Safety Lamps, 177. Kinds

X CONTENTS

PAGB

of Locks; Lead-Plug Lock, Protector Lock, Magnet Lock,
Air Lock, 178.
Photometry of Safety Lamps 287

Forecast, 179. Classification of Illuminating Flames;
Candle Flames, Oil-fed Flames, Gas-fed Flames, 180.
Nature and Persistence of Flames, 181. Causes Producing
Extinction of Flames, 182. Standard Flame or Light Unit,
183. The Photometer; Bunsen's Photometer, 184. Illum-
inants for Safety Lamps; Solid Paraffin, Acetylene Gas.
Vegetable Oils; Rape, Colza — "Winter Rape, Summer
Rape. Animal Oils; Lard Oil, Fish Oils — Sperm Oil,
Whale Oil, Seal Oil. Mineral Oils; Petroleum or Rock
Oil — Light or Highly Volatile Oils, Kerosene or Coal Oil,
Gasoline (Colzalene), Naphtha or Benzoline, Benzine,
Refined Petroleum, 185. Flashing Point of Oils, 186.
Comparison of Oils and Candles, 187. The Smoke Test,
188. Wicks and Wick Tubes for Safety Lamps; Wicks,
Pricker, 189. Illuminating Power of Different Safety
Lamps, 190.

CHAPTER VII
Testing for Gas -- 308

Gas Indicators 308

Forecast, 191. Monnier, Coquillion, Maurice, 192.
Aitken, 193. Ansell, Libin, 194. Aitken, Smith, 195.
The Liveing Indicator, 196. The Forbes Indicator, 197.
The Garforth Appliance, 198. Other Devices, 199. Signal
Apparatus, 200. Shaw's Signaling System, 201. The
Shaw Gas Machine, 202. Use of the Shaw Gas Machine,
203. The Beard-Mackie Sight Indicator, 204. Principle
of the Sight Indicator, 205. Experiments Previous to
Calibration; Beard's Test Chamber, Galloway's Law
Confirmed, 206. Calibration of the Sight Indicator, 207.
Advantages of the Sight Indicator, 208.

The Flame Test - - - 331

Early Practice, 209. The Visible Effect of Gas on
Flames, 210. Relation of Height of Flame Cap to Per-
centage of Gas; Galloway's Law, 211. Flame Caps of
Different Illuminants in Different Lamps, 212. Measure-
ment of Flame Caps in Testing Lamps; Clowes Scale

CONTENTS xi

PAGE

(Hydrogen Flame), Pieler and Chesneau Scales (Alcohol
Flame) , Platinum-Wire Scale of the Beard-Mackie Lamps
(Sperm-Oil Flame), 213. Care of Lamp, 214. Examin-
ing a Mine for Gas, 215. Making a Test for Gas with a
Davy Lamp ; Cap Test by Reduced Flame, Normal Flame,
216. Comparative Merits of the Flame Test and the Sight
Indicator, 217. Measurement of Gas in Mines, 218.

Care of Miners' Safety Lamps 348

Ownership and Control of Lamps, 219. Requirements,
220. The Lamp House, 221.

ADDENDA

Standards of Weight and Measure --------- 353

Importance of Uniformity of Standards. Fruitless
Efforts to Establish Natural Standards. The English
Standard (Imperial) Yard. --_---____ 353

The Seconds Pendulum, London. British House of
Parliament Burned and Standard Lost — New Standard
made without Reference to Natural Standard. Volume
and Weight of Distilled Water at Maximum Density (4'^C.)
Weighed in a Vacuum, is the Adopted Base of Comparison
and Reference. Difference in Legal Standards of Great
Britain and France. The English Standard Gallon. - - 354

Standard in Common Use in the United States Derived
from English Standards. The English Value for the
Meter. ----------' 355

Units of Length, Weight, and Volume; In England,
France, and the United States. Difference Between the
Values of the Meter in Great Britain and the United
States. _-.____. 356

Formula Expressing the Relative Density of Distilled
Water, at any Temperature.
The Metric System

Early History of the Metric System. When Legalized
in the United States. ----- 357

The Unit of Length (Meter) the Base of the System.
The Unit of Weight (Kilogram) is the Mass of One Cubic
Decimeter of Distilled Water (4^ C.)- The Unit of Capac-
ity (Liter) is the Volume of One Kilogram of Distilled
Water (4° C.) . Establishment of the International Bureau
of Weights and Measures, by an Agreement Signed by
Seventeen Countries. -- .-_.. 353

xii CONTENTS

PAG8

New Standards Made by International Committee and
Copies Sent to the Several Governments.
Fundamental Equivalents

Values of the Standard Units of Length, Weight, and
Capacity in General Use. The Avoirdupois, Troy and
Apothecaries Grains are of Equal Value. ------ 359

Conversion Tables

United States to Metric and Metric to United States

Values. 360-1

Constants and Units of Reference

Need of Uniformity in Constants and Units of
Reference Used. The Constants and Units of Reference
Used in this Treatise have been carefully selected, as
being those most generally accepted and correspondent to
each other or derivable alike from each other. - - - - 362

Weight of Unit Volumes of the Common Standards —
Water, Air, Hydrogen, and Mercury. ------- 363

INDEX TO TABLES

TABLE PAGB

1. Important Mine Gases 3

2. Atomic Weight? of the Elements 8

3. Specific Gravities and Weights of Substances 22

4. Specific Heats of Air, Mine Gases, and Vapors, 49

5. Heat of Combustion of Substances Burning in Oxygen. ... 65

6. Values of Gravity at Different Latitudes (Sea Level) 76

7. Effect of Elevation on Pressure and Density of Air 88

8. Average Temperatures of Air Columns 89

9. Pressure (Tension) of Aqueous Vapor 95

10. Amount and Composition of Gas Evolved from Different

Coals, at 212° F 102

11. Composition of Gases taken from Mine Blowers and Bore

Holes 103

12. Inflammable and Explosive Limits and Maximum Ex-

plosive Point of Methane (Marsh Gas), showing Per-
centage of Gas in Mixture 103

13. Rates of Transpiration of Mine Gases 119

14. Rates of Diffusion of Mine Gases 124

15. Explosive Range of Mine Gases 137

16. Residual and Artificial Atmospheres Extinctive of Candle,

Oil-fed, and Gas-fed Flames — Clowes 140

17. Composition of Firedamp Mixtures Rendered Non -explosive

or Extinctive of their own Flame, or Incombustible

by the Addition of Certain Gases 140

18. Composition of Fatal Atmospheres, showing Least Per-

centages of the Principal Mine Gases Producing Fatal

Results in Otherwise Good Air 144

19. Temperatures of Ignition of the Inflammable Mine Gases. 149

20. Absorptive Power of Mine Gases , 150

21. Heat Energy of Different Combustibles 152

xiii

xiv INDEX TO TABLES

TABLE PAOB

22. List of Mine Explosions Officially Reported in the United

States and Canada, Numbering five or more Fatalities,
Since January, 1896 189

23. Computed and Estimated Temperatures of Explosion of

Various Explosives 200

24. Average Illuminating Power of Different Safety Lamps. . . 306

25. Heights of Flame Caps for Different Illuminants and

Lamps — Reduced Flame 335

Addenda

Fundamental Equivalents (U. S. Legal Standards) 359

Conversion Tables — United States and Metric Weights and

Measures 360-1

Weights of Unit Volumes of the Common Standards — Water,

Air, Hydrogen, and Mercury 363

INDEX TO ILLUSTRATIONS

FIGURE PAGB

1. The Hydrostatic Balance 17

2. Determining Specific Gravity by a Balance 18

3. Specific Gravity Bottle 20

4. The Nicholson or Fahrenheit Hydrometer 20

5. The Baume Hydrometer 21

6. Comparison of Thermometer Scales 43

7. Expansion of Air and Gases 56

8. Showing Upward Pressure of the Air 7^ 1

9. Showing Column of Mercury Balanced by the Pressure

of the Atmosphere 81

10. The Mercurial Barometer 82

11. The Aneroid Barometer 84

12. Leslie's or Mason's Hygrometer 97

13. The Blood Test for Carbon Monoxide 107

14. Showing Face of Chamber, and Gas Working in Coal 120

15. Breathing Apparatus — Rescue Work 184

(a) Vajen-Baden Helmet

{b) Shamrock (Meyer) Apparatus

16. An Underground Hospital 187

17. The Speddmg Steel Mill 216

18. The First Safety Lamp— Dr. Clanny 217

19. Showing Attachment of Gauze to Lamp and General

Arrangement of Parts 22 1

20. Showing Principle of Eloin Safety Lamp, Admitting Air

below the Flame 231

21. Unbonneted Davy Lamp 234

22. Fire-boss Davy Lamp 235

xvi INDEX TO ILLUSTRATIONS

FIGURE PAGE

23. Hughes, Evan Thomas Lamp 237

24. The Scotch Davy Lamp 238

25. Improved Unbonneted Clanny Lamp 242

26. Evan Thomas No. 7 Lamp 243

27. Mauchline, Bull's Eye, Clanny Lamp 246

28. Bonneted Marsaut Lamp — Three Gauzes 247

29. Gray No. 2 Lamp 249

30. The Ashworth Testing Lamp 251

31. Vessels of the Ashworth No. 4 Lamp 252

(Paraffin, Alcohol, Oil)

32. Ashworth-Hepplewhite-Gray Lamp, Short Pattern 253

33. Showing Manner of Testing for Gas with the A-H-G. Lamp 254

34. Standard A-H-G Lamp 255

35. Improved A-H-G Lamps 257

36. Beard Deputy Lamp 258

37. English Mueseler Lamp 259

38. Belgian Mueseler Lamp 261

39. The Pieler (Alcohol) Testing Lamp 263

40. The Chesneau (Alcohol) Testing Lamp. 265

41. The Stokes Testing Lamp 268

42. The Ashworth Tester, Oil-Alcohol 269

43. The Clowes Hydrogen Lamp 270

44. Section of Clowes Hydrogen Lamp ; 271

45. Beard-Mackie Lamp (English Model) 273

46. Igniter (Wolf) Detached from Lamp. . .• 274

47. The Wolf (Naphtha-Benzine) Lamp 275

48. Detail Section of Oil Vessel of Wolf Lamp 276

49. Tank for Filling Wolf Lamps with Naphtha 279

50. Oil Vessel Fitted with Lead-Plug Lock 282

51. Improved Rivet Mold 282

52. Sectional View of Protector Lock 283

53. Showing the Operation of the Wolf Magnetic Lock 285

54. American Safety Lamp Company's Magnet Lock 285

55. Showing Operation of the Air Lock 286

56. Bunsen's Photometer 291

57. A Practical Smoke Test for Illuminating Oils 302

58. Section of the Liveing Gas Indicator 311

59. The Shaw Gas Machine. 318

60. The Beard-Mackie Sight Indicator Detached from Lamp.. 324

61. The Beard-Mackie Sight Indicator in Davy Lamp 326

62. Test Chamber Used in Calibrating the Beard-Mackie Sight

Indicator 327

INDEX TO ILLUSTRATIONS XVll

FIGURE P OE

63. Section of Oil "^'essel of Clowes Hydrogen Lamp, Showing

attached Scale for Measurement of Flame Caps 337

64. Lamp Brushes, Gauzes, and Glass 339

65. Making a Test for Gas 342

66. Showing Condition with Respect to Gas at Face of a

Chamber 346

67. Showing Arrangement of Lamp House 350

68. Receiving Lamps at the Lamp House 35 L

MINE GASES AND EXPLOSIONS

MINE GASES
INTRODUCTION

1. Natural Conditions. — The subject of Mine Gases is
preliminary to that of Mine Ventilation; the latter is not
complete without the former. The efficient ventilation of
a mine requires the removal of the gases that are generated
in the mine and those that flow from the strata; the re-
moval of these gases is effected through the agency of a
current of air circulated through the mine and known as
the air-current or ventilating current. There always exist
in mines important natural conditions relating not only to
the strata but to the atmosphere and the gases themselves,
which affect the efficient ventilation of the mine. Such
conditions arise from the existence of gas in the strata en-
folding the coal or in the seam itself, the nature of the gases
thus confined, and the changes of atmospheric pressure,
which affect their outflow from the strata into the mine air.

2. Natural Laws. — There are besides numerous natural
laws, both chemical and physical, that play an important
part in determining the condition of the atmosphere of a
mine and thus form a vital part of the subject of Ventila-
tion. Such are the laws of chemical affinity, the constitu'

2 MINE GASES AND EXPLOSIONS

tion of matter, chemical reactions, the laws of heat and its
relation to temperature, atmospheric pressure, the rela-
tion of the volume and density of air and gases to their
temperature and pressure, and the laws relating to the
emission and diffusion of gases.

The generation of gases in the mine, their behavior and
properties, and the means used to detect their presence and
avoid the dangers they present, form likewise a preliminary
study to the Ventilation of Mines.

3. Occurrence of Mine Gases. — The gases met with in
mines and which contaminate the mine air are either
formed in the mine by the slow combustion of fine coal or
other carbonaceous matter in the waste, or are produced
by mine fires, the explosion of powder, burning of lamps,
decay of timber, breathing of men and animals, etc.; or
they exude as natural gas from the strata. The various
forms of combustion (oxidation) that are continually going
on in the mine consume the oxygen of the mine air, and
the remaining large quantities of nitrogen form no small
proportion of the mine gases that must be removed by the
means of ventilation.

4. Important Mine Gases. — Following are the most im-
portant of the mine gases, given in the order of their
importance with respect to health and safety in the mine,
together with the chemical symbol of each gas, its specific
gravity referred to air, the density referred to hydrogen,
and the molecular weight of the gas. It will be observed
that the molecular weight of hydrogen being 2, the density
of each gas referred to hydrogen is one-half its molecular
weight. These gases are fully described in Chapter IV.

To understand thoroughly the behavior of mine gases it
is necessary to study carefully the physical laws affecting
them.

INTRODUCTION.

Table 1
important mine gases

Gas

Methane

Light carbureted hydrogen

Marsh gas

Carbon monoxide \

Carbonic oxide ]

Carbon dioxide \

Carbonic acid /

Hydrogen sulphide
Sulphureted hydrogen
defiant gas '
Ethylene
Ethene

Ethane

Nitrous oxide (laughing-gas)

Oxygen

Nitrogen

Hydrogen

Symbol

Specific
Gravity
Air = l

Density
H = l

Molecular
Weight

CH,

CO2
H2S

C2H4

C,H,
N2O

.559

.967
1.529
1.1912

.978

1.0366
1.525
1 . 1056
.9713
.06926

14
22

15
22
16
14
1

28
44
34

30
44
32
28
2

CHAPTER I
THE CHEMISTRY AND PHYSICS OF GASES

5. Chemistry is that branch of science that treats of
the composition of substances and the alterations they
undergo by a change in the kind, number, and relative
position of their atoms. Chemistry considers the force
(a-ffinity) that binds atoms together to form molecules,
the union and dissociation of atoms, their interchange or
rearrangement to form new molecules; and studies the
properties of the different substances thus formed.

The study of chemistry as outlined in the following pages
has a most important bearing on the subject of Mine Gases
and Explosions, and is necessary to a thorough and intelli-
gent understanding of the principles and practice of the
ventilation of mines.

6. Physics is that branch of science that treats of the
relation of force to matter; the physical constitution of
matter; and studies the nature and effects of the forces
acting on matter and the changes they produce.

The relation of chemistry to physics is thus seen to be
very close; each year the study of physical chemistry is
becoming of greater interest, as furnishing facts of vast
importance to practical operations and industries. Present
knowledge of these subjects is very incomplete, and it is
often difficult to discriminate between theories that are
still regarded as problematical and those that have been so

MATTER 5

far authenticated as to have been generally accepted. The
atomic theory of Dalton ranks to-day in the latter class,
while the later theory of electrical dissociation or ionization
has not as yet reached that stage of development that its
nature and Hmits are clearly defined. It has, however,
long since earned its right to consideration and is steadily
gaining favor. So much cannot be said of certain theories
of so-called corpuscles, assumed to be the ultimate particle,
in the hope of explaining the differences in elementary atoms.

MATTER

7, Matter is substance, aggregation of elemental atoms
the existence of which is perceived by sense, or may be
demonstrated by deduction; in other words, matter is
what composes the universe. Mass is amount of matter;
the mass of a body is the amount or quantity of matter it
contains. Density is degree of concentration of matter;
hence the quantity of matter in a given volume of a body
determines its density.

8. State of Matter. — There are two general conditions of
matter, which are described as solid and fluid, and the
latter is again subdivided into the liquid and gaseous.
Matter, therefore, exists in three states or conditions — the
solid, liquid, and gaseous. Matter in the solid state is
characterized by the comparative rigidity or fixedness of
its molecules, which move among themselves with diflfi-
culty. The fluid state of matter (liquids and gases) is
characterized by the ease with which the molecules of the
matter move among themselves.

The same matter may exist in any or all of these forms,
accompanied with a change in density. The two agencies
that are effective in producing a change in form from one

6 MINE GASES AND EXPLOSIONS

state to another are heat and "pressure; these act in oppo-
site ways and produce opposite effects. An increase of
heat in a substance acts to drive the molecules farther
apart and increases their rapidity of motion, causing expan-
sion and decreasing the density of the substance. On the
other hand, an increase of pressure drives the molecules
nearer together and increases the density of the substance.
Cold, or the absence of heat, united with pressure consti-
tutes the most powerful means of increasing the density of
matter. For example, water exists as ice at temperatures
below 32° F., and as steam at temperatures above 212° F.,
at sea-level. Air, hydrogen, or other like substances that
exist as gases at ordinary temperatures and pressures may
be changed to a liquid or even a solid by a decrease of
temperature combined with an increase of pressure. By
the same agency, also, the temperature at which a given
soUd is converted into a liquid (melting-point), or the tem-
perature at which a given liquid is changed into a gas or
vapor (boiling-point) is lowered by a decrease of pressure
and raised by an increase of pressure.

9. Divisions of Matter. — The smallest conceivable divi-
sion of matter is called an at(ym, and two or more atoms
chemically combined form a molecule. Recently science
has demonstrated the fact that matter is capable of still
other divisions than the atom and molecule, and these
resulting particles are called ions.

The ion is the result of an electrical division of matter.
It is an electrically charged particle, and may bear a
charge of positive electricity, when it is called a cation;
or of negative electricity, when it is called an anion. Ions
may be elemental in character like atoms, or complex like
radicals. When deprived of their electrical charge they
Again assume molecular condition.

MATTER 7

The atom is the smallest particle that is assumed to
take part in a chemical reaction, by which is understood an
interchange of the atoms forming molecules of unlike sub-
stances. An atom, it is assumed, cannot exist in a free or
uncombined state, except as an ion when electrically charged.

The molecule is the smallest particle that is assumed to
exist in a free or uncombined state, except when such
particles are electrically charged as ions. Like atoms
unite to form simple molecules; unlike atoms form com-
pound molecules.

10. The Elements. — At present there are 78 kinds of
matter known to the chemist; these are called elements.
Elementary matter is that composed of simple molecules
only, or molecules whose atoms all consist of the same
kind of matter. When the atoms forming the mole-
cules of a substance are of two or more kinds of matter,
the substance is a compound.

A compound substance may be either a mechanical
mixture or a chemical compound. Where the molecules of
two or more unlike substances or kinds of matter are simply
mixed, and exist side by side, and do not act on each other
chemically, but each retains its original identity, and may
be separated by suitable means without in any way under-
going change, the compound is a mechanical mixture. It
differs from a chemical compound in that the different
kinds of matter forming it are mixed in any proportion,
and the properties of the mixture vary with the amounts
of the several ingredients.

A chemical compound always possesses the same proper-
ties, because the components are always combined in fixed
proportions.

Table 2 on the following page gives the names of all the
elements known at the pnisent time, together with their

8 MINE GASES AND EXPLOSIONS

symbols and atomic weights referred both to hydrogen and
to oxygen as units.

Table 2
atomic weight of the elements

Element

Aluminum, .
Antimony. .

Argon

Arsenic ....
Barium. . . .
Bismuth. . . .

Boron

Bromine. . . .
Cadmium. . .
CsBsium. . . .
Calcium. . . .

Carbon

Cerium

Chlorine . . .
Chromium. .

Cobalt

Columbium .

goPPe^

Erbmm. . . .

Fluorine. ...

Gadolinium.

GaUium

Germanium.

Glucinum. . .

Gold

Helium

Hydrogen .

Indium

Iodine

Iridium

Iron

Krypton . . .

Lanthanum.

Lead

Lithium. ...

Magnesium. .

Manganese. .

Mercury. ...

Molybdenum

Atomic Weight

H = l 0 = 16

119

136

206

111

131

139

164

18,

154,

72.

195,

114,

126

191.

137

205

198

27,

120,
39
75

137

208
11
79

112

132
40
13

140
35
52
59
94
63

166
19

156,

70,

72,

197.
4.
1.

115.

126.

193,
55,
81.

138.
35206.

200

1
2

008

Element

Neodymium .

Neon

Nickel

Nitrogen . . .

Osmium ....
Oxygen

Palladium. . .
Phosphorus .
Platinum . . .
Potassium . .
Praseodymium
Radium. . . .
Rhodium. . .
Rubidium . .
Ruthenium.
Samarium. .
Scandium. .
Selenium. . .

Silicon

Silver

Sodium ....
Strontium. .
Sulphur. . .
Tantalum . .
Tellurium . .
Terbium. . . .
Thallium. . .
Thorium . . .
Thulium. . . .

Tin

Titanium. . .
Tungsten . .
Uranium. . .
Vanadium. .

Xenon

Ytterbium. .
Yttrium. . . .

Zinc

Zirconium. .

Atomic Weight

H = l 0 = 16

142.

19.

58.

13.
189.

15.
105.

30.
193.

38.
139.
223.
102.

84.
100.
149.

43.

78.

28.
107.

22.

86.

31.
181.
126.
158.
202.
230.
169.
118.

47.
182.
236.

50.
127.
171.

88.

64.

89.

143.6
20.
58.7
14.04

191.
16.

106.5
31.

194.8
39.15

140.5

225.

103.
85.5

101.7

150.3
44.1
79.2
28.4

107.93
23.05
87.6
33.06

183.

127.6

160.

204.1

232.5

171.

119.
48.1

184.

238.5
51.2

128.

173.
89.
65.4
90.6

MATTER 9

For the sake of easy reference the elements used in this
book and which are of the most importance to the student
of ventilation are set in heavy-faced type, together with
their symbols; the atomic weights of these elements
commonly used are likewise set in heavy-faced type.

11. Forces Inherent in Matter. — Affinity is a chemical
force acting to bind atoms together to form molecules.
The atoms of the several elements have a greater or less
affinity for each other, causing them to form compounds
more or less stable, accordirg to the strength of the affinity
of the combining atoms. Water is one of the most stable
compounds, because of the great affinity of the hydrogen
and oxygen atoms forming the molecule of water. The
separation of the atoms forming a molecule is called dis-
sociation, which is the reverse of what takes place when
the atoms combine.

The various forms of attraction are known as gravitation,
cohesion, adhesion, and magnetism; these forces are exerted
between molecules or masses of matter.

12. Gravitation is the attraction that exists between the
earth and all bodies on and around it. The attraction is
mutual, and since the mass of the earth is constant the
attractive force is directly proportional to the mass of the
body. Where the latter is free to move, it falls in a straight
line which, if continued, would pass through the center of
the earth's mass.

13. Cohesion and Adhesion are the forces that bind
molecules together, giving to matter its form and continu-
ity. Cohesion, however, binds together the molecules of
like matter, while adhesion joins the surfaces of like or
unlike matter. Thus, cohesion holds together the mole-
cules of glue, while adhesion causes the glue to adhere to
other substances, such as wood or other like material.

10 Mine gases ANb explosions

14. > Magnetism is the term employed to denote the
cause, as well as the resulting phenomena, of the attraction
and repulsion some substances have for other substances.
This attraction was first observed in magnetic iron oxide.

PROPERTIES OF MATTER

15. Constitution of Matter. — The theory most widely
accepted in modern times as best explaining all the various
phenomena of matter is that known as the atomic theory
proposed by Dalton in 1808, and which conceives of all
matter as made up of parts or atoms capable of motion
among themselves, and possessing a greater or less degree
of attraction for each other. This condition or state con-
siders what may be called the chemical division of matter,
and is, we may assume, sufficient for the full explanation
of the various chemical changes that take place in matter,
and the physical effects of heat, causing expansion or con-
traction, and tension or pressure, in a body. It will be
assumed, also, that the consideration of this condition of
matter is sufficient for the purposes of this volume, although
it has been suggested by an eminent authority (Ashworth)
that it is possible a closer study of the electrical division
of matter may furnish a more adequate and satisfactory
explanation of some of the phenomena attending large mine
explosions. This does not seem improbable since, as far
as investigation has gone, the forces concerned in the elec-
trical division of matter appear more powerful by far
than any of the physical or chemical forces known to us.
However, this condition of matter has not as yet been suf-
ficiently analyzed to form a part of a concrete science.

16. Volume. — The volume of a body is the space it
occupies. The volume of a body of regular shape may be

PROPERTIES OF MATTER U

calculated by finding the product of its several dimensions
in accordance with the rules of mensuration. When a
body is of irregular shape, its volume is determined prac-
tically by measuring the quantity of liquid it displaces
when immersed in a Hquid in which it is insoluble. The
volume of any body is always equal to its displacement
when immersed.

17. Mass. — Mass is amount of matter; the mass of a
body is the amount of matter forming the body.

18. Density. — In a general sense density is compactness
of mass, or mass per unit of volume. In a more specific
sense density is the relative degree of compactness of
matter, and has reference to the amount of matter in a
given volume of a body as compared with the amount of
matter in a like volume of another body taken as a
standard or unit. The densities of the several mine gases
referred to hydrogen as unity are given in Table 1; from
this table it is observed that methane is 8 times, oxygen
16 times, and carbon monoxide, olefiant gas, and nitrogen
each 14 times as dense as hydrogen gas. In other words,
these gases contain severally 8, 16, and 14 times as much
matter as hydrogen, volume for volume.

19. Compressibility. — The effect of pressure on matter
is to press its molecules nearer together and thus reduce its
volume. All forms of matter are not alike compressible,
gases being most and liquids least compressible. The
compressibility of a body is evidence of its porosity, or
of the space between its molecules, and reveals the pos-
sibility of these molecules moving freely among them-
selves, which molecular motion is independent of any
motion of the body itself. The compression of most gases
beyond a certain limit changes the gas to a liquid. A re-
duction of temperature always greatly assists these changes,

12 MINE GASES AND EXPLOSIONS

owing to the abstraction of heat from the matter com-
pressed.

20. Elasticity.— The elastic force of a body is the force
with which its molecules resist compression. The elastic
force of a gas is called the pressure or tension of the gas;
heat increases the tension of all gases, which thus require
a greater force to compress them as the temperature is
increased. As before (Art. 19), gases are the most elastic
and liquids the least so of all the forms of matter.

21. Viscosity.— The particles of all fluids always adhere
slightly to each other and when put in motion attempt
to drag adjacent particles along, or, conversely, hold them
back from being drawn away. This property is called vis-
cosity, and when highly marked, a liquid is said to be
^Wiscous," sticky or adhesive. Gases, also, possess more
or less viscosity. The viscosity of air greatly increases the
frictional resistance of airways through which the current
passes.

22. Porosity. — This term relates to the pores of a solid
body, or the spaces that exist naturally between the mole-
cules of such a body. All solids are more or less porous.
The porosity of a body determines the ease with which air,
water, or other fluids will pass through it or be absorbed
by the solid.

23. Capillary Action. — This term describes the attrac-
tion that takes place between a liquid and a solid when
the two are brought in contact with each other. It is
owing to the force of capillary attraction that liquids are
absorbed in the pores of a solid and drawn upward, the
capillary force overcoming the force of gravity. The action
is strongest in fine capillary tubes, from which cause its
name is derived. Capillary attraction varies inversely as
the diameter of the pores, and is also different for different

PROPERTIES OF MATTER 13

liquids and solids. In some cases, instead of attraction,
repulsion takes place bet^ween the liquid and the solid; for
example, attraction results between glass and water after
the glass has been wet, but repulsion between glass and
mercury. The attraction or repulsion will depend on
whether or not the liquid wets the solid.

24. Transpiration, Diflfusi on. —Transpiration, otherwise
called effusion, relates to the passage or flow of a fluid
through the pores of a solid, as the outflow of gas from an
exposed face of coal. Diffusion relates to the intermixing
of the molecules of fluids in contact with each other, as
the diffusion of the mine gases into the air and into each
other in the mine. These important properties of gases
will be studied in detail later.

25. Conductivity. — Conductivity is the power of matter
to convey or transmit any molecular sensation or condition
from one molecule to another. It varies greatly in differ-
ent kinds of matter, and indicates in a general way the
resistance such matter offers to transmission.

26. Inertia. — Inertia is that property of matter by virtue
of which a body remains in a state of rest or motion till
acted on by a force. Matter at rest will remain at rest till
some force acts on it and imparts to it motion; matter in
motion will continue to move till some resisting force
brings it to rest. Inertia is therefore of two kinds, inertia
of rest and inertia of motion.

27. Heat is a condition of matter caused by an exceed-
ingly rapid oscillatory or vibratory motion of its molecules,
and manifesting itself as a particular sensation, which the
human senses discern as temperature. The intensity of
the heat is directly proportional to the velocity and ampli-
tude of the vibrations. A hotter body in contact with a
colder one imparts to the latter more molecular motion

14 MINE GASES AND EXPLOSIONS

than it receives, and the loss of the hotter body in energy
is the exact equivalent gained by. the colder body. In a
generic sense the term describes a condition or state of
matter that is capable of being measured as energy is
measured; and so we determine the quantity of heat in a
body as we would measure the amount of energy. It is
in this sense that the term is used in science. (See
Chapter II.)

28. Weight. — Weight or gravity are terms used to de-
scribe the effect produced or the property conferred on
matter by virtue of the attraction of the earth. Hence
weight is a property that all matter possesses by virtue of
the attraction of the earth. The weight of a body is the
static measure of the force of gravitation exerted on that
body; and since this force is exerted alike on each unit of
mass, the weight of a body is always proportional to its
mass, at the same place. It is evident that if all matter
were of equal density the weights of equal volumes of ah
matter would be equal; but as this is not the case, the
relative weights of equal volumes of matter express the
relative densities of such matter. The English unit of
weight is the pound, but owing to the variation of the
force of gravity this is not an absolute unit.

29. Atomic Weight. — Dalton's atomic theory ascribes
weight to every atom, but the size of an atom being
inappreciable its weight cannot be expressed in units
of any denoixdnation; so that the actual weight of an
atom of any kind of matter is at present mere speculation.
By means of many careful gravimetric and volumetric
determinations, however, the relative weights of different
kinds of matter have been accurately ascertained. Hydro-
gen has been found to be the lightest form of matter known,
and the hydrogen atom has therefore been chosen as the

PROPERTIES OF MATTER 15

unit of atomic weight; the weights of the other atoms are
expressed in terms of this unit. Hence atomic weight is
only relative weight, expressed in terms of the weight of
an atom of hydrogen. Thus the atomic weight of hydro-
gen being 1, that of nitrogen is 14, oxygen 16, etc. It
will be seen presently that the atomic weights of the
simple mine gases are the same as their densities.

30. Molecular Weight. — Molecular weight is the sum
of the atomic weights of the atoms forming a molecule.
The molecular weights of the common mine gases given
in Table 1 will be seen later to be equal in each case to
the sum of the atomic weights of the combining atoms,
and in the case of the simple mine gases, hydrogen, nitro-
r;on, and oxygen, the molecular weight in each case will be
found to be twice the atomic weight of the gas.

31. Atomic and Molecular Volumes, Specific Volume. —
The same careful gravimetric and volumetric determinations
of matter previously referred to in relation to atomic weight
have established the law of volume that has since come to
be known as Avogadro's law: Equal volumes of gases at
the same temperature and pressure contain the same number
of molecules. This is equivalent to stating that all gaseous
molecules at the same temperature and pressure are of the
same size. This law applies without exception to all the
mine gases, and is of importance in determining the relative
volumes of air and gases consumed and of gases produced
in any chemical reaction. Chemical hypothesis assumes
that all simple gaseous molecules contain two atoms each,
and while a compound molecule may contain any number
of atoms it is still of the same size as the simple molecule,
or twice the size of the hydrogen atom. Hence calling the
volume of the hydrogen atom 1, the volume of any gaseous
molecule is 2, whatever the number of atoms it may

16 MINE GASES AND EXPLOSIONS

contain. Atomic and molecular volumes, sometimes
called specific volumes, are simply relative volumes, as
atomic and molecular weights are relative weights.

Since the atomic weight of hydrogen is 1, its molecular
weight is 2 ; and since all gaseous molecules under like con-
ditions are of equal size, the molecular weight of any gas
may be compared with the molecular weight of hydrogen
to ascertain the density of such gas, which density will
therefore be one-half the molecular weight of the gas, the
density of hydrogen being unity.

SPECIFIC GRAVITY

32. The term specific gravity means the ratio of the
weight of any given volume of a substance to the weight of
an equal volume of another substance taken as a standard.
This term has practically the same meaning as density,
but compares the weights of equal volumes, while density
relates directly to the masses of equal volumes of different
solids, Hquids, or gases. Density is, therefore, relative
mass, while specific gravity is relative weight. Each of
these terms has its own particular significance, which
should determine its use; the terms should not be used
interchangeably, as they are by some writers. In a general
sense, however, the density of a body is made known by
ascertaining experimentally its specific gravity. While
density depends upon a purely assumed basis, specific
gravity has a gravimetric value that is tangible. Calling
the density of hydrogen 1, that of nitrogen is 14, which
means that nitrogen contains fourteen times as much
matter, volume for volume, as hydrogen, on the assumed
chemical hypothesis. Again, the specific gravity of nitrogen
referred to air as unity is .9713, which means that any

SPECIFIC GRAVITY

given volume of nitrogen weighs but .9713 of the weight
of an equal volume of air, under the same conditions of
temperature and pressure. It is evident from the fore-
going that the density of air referred to hydrogen as unity
is 14^ .9713 = 14.4, as shown in another way later (Art. 43).
33. Methods of Determining the Specific Gravity of
Solids, Liquids, and Gases. — These may be divided into
three classes, according to the kind of apparatus used;

Fig, 1. — The Hydrostatic Balance.

namely: 1. Method by balances. 2. Method by specific-
gravity bottle. 3. Method by hydrometer. All of these
methods depend on the principle of Archimedes. When
a body is submerged in water the volume of water displaced
is always equal to the volume of the body itself, and
Archimedes discovered that the buoyant or upward pres-
sure exerted on the submerged body — its loss in weight — is
equal to the weight of the water displaced. This principle
is clearly demonstrated by what is known as the hydro-
static balance, shown in Fig. 1. A solid cylinder a is

MINE GASES AND EXPLOSIONS

suspended from the bottom of an empty cup t, which
hangs beneath one of the scale-pans of a balance. The
volume of the cylinder is exactly equal to the capacity of
the cup, and their weight is balanced by the weights in
the opposite scale-pan. Water is now poured into the
jar until the solid cylinder is completely submerged,
which causes the scale-pan on that side of the balance to
rise, but by now fiUing the empty cup t with w^ater the
balance is again restored, showing that the upward pres-
sure on the submerged cyUnder is equal to the weight of
the water displaced.

34. Method by a Balance. — This method is shown in
Fig. 2, and is practically what has just been explained.

The substance whose specific
gravity is to be determined
is suspended beneath one
scale-pan and its exact
weight (W) found by weights
placed in the opposite pan.
Water is then poured into
the glass and the weight
(w) of the submerged
body found. The difference
(W — w) of these weights is
the weight of the displaced water, whose volume is equal
to the volume of the substance. The specific gravity
is then the ratio of the weight of the substance in air to
its weight in water; or

Sp-gr- = :z^T:.- ...... (1)

Determining Specific Gravity by a
Balance

To determine the specific gravity of a liquid by a balance
the weight of a coin or other substance is found first in

SPECIFIC GRAVITY 19

air {W), then in water {w\), and afterwards in the Hquid
{W2) whose specific gravity is to be determined. Then,
since W —W2 equals the weight of a certain volume of the
liquid, and W — Wi equals the weight of an equal volume
of water, the specific gravity of the liquid is the ratio of
the former to the latter; or

^ W — W2 /0\

^P-S'^-W^, (2)

To determine the specific gravity of a gas by a balance,
a glass globe of any given capacity is used, being provided
with a stop-cock in the neck, by means of which it may
be closed after the air has been exhausted with an air-
pump. The weight of the globe is found first empty (w),
then filled with air (TFi), and finally filled with the gas
(W2) whose specific gravity is to be determined. Then,
since W2—W is the weight of a certain volume of the gas,
and Wi—w is the weight of an equal volume of air, the
specific gravity of the gas is the ratio of the former to
the latter; or

o W2 — W .^.

SP-g'--=F731i, (3)

To determine the specific gravity of a liquid, or of any
solid in fine grains or powder, a glass bottle is used (Fig. 3)
provided with a ground glass stopper perforated with a
fine capillary bore for the escape of any excess of liquid.

To determine the specific gravity of a liquid the weight
of the bottle is found first empty (w), then filled with
water (Tf 0, and finally filled with the liquid (TF2). The
specific gravity of the liquid is then given by formula 3,
above.

To determine the specific gravity of a solid in grains

MINE GASES AND EXPLOSIONS

or powder its exact weight (W) is first found, then the
weight (wi) of the bottle filled with water, and finally
the weight {W2) of the bottle filled with
water and containing also the substance.
Then the specific gravity of the substance
is the ratio of the weight (W) of the sub-
stance to the weight {W +W1—W2) of the
water displaced from the bottle when the
substance was introduced; or

Sp. gr. =

Fig. 3

Specific-gravity

W+W1—W2'

(4)

Bottle

If a substance is soluble in water its
specific gravity may be determined by
using, instead of water, another liquid in which it is in-
soluble and afterwards finding the specific gravity of such
liquid. The product of these two specific gravities will
be the specific gravity of the substance referred to water,
35. Method by the Hydrometer. — There are two types
of the hydrometer used. The Nicholson or Fahrenheit
hydrometer (Fig. 4) has a constant immer-
sion or displacement but a variable weight,
small weights being added to the scale-pan
a at the top of the stem c, to sink the hy-
drometer to the standard mark upon the
stem. This hydrometer is provided with a
lower scale-pan d and can be used to de-
termine the specific gravity of a solid
insoluble in and heavier than water. The
solid whose specific gravity is to be deter-
mined is first placed in the upper scale-pan
and a sufficient number of weights added
to sink the hydrometer to the mark. This weight subtracted

Fig. 4
The Nicholson
or Fahrenheit
Hydrometer

SPECIFIC GRAVITY

from the weight required to sink the hydrometer alone to
the mark will give the weight of the substance in the pan.
The substance is now removed to the lower pan, where it
will be immersed in the water and thus add to the dis-
placement. It will now require a less weight to sink the
hydrometer to the mark, and the difference is the weight
of the water displaced. The weight of the substance
divided by the weight of the displaced water will give
■ the specific gravity of the substance.

To determine the specific gravity of a liquid by this
hydrometer, the sum of the weight of the hydrometer iW)
and the additional weights {W2) required to sink the hy-
drometer in the liquid is divided by the sum of the weight
of the hydrometer and the weights required to sink the
same in water (TF+t^i); thus,

Sp. gr.

W-\-W2

(5)

The Baume hydrometer (Fig. 5), unlike the Nicholson,
has a constant weight but a variable im-
mersion, the stem being graduated to read
the strength of the Uquid to a scale called
the Baume scale. Both of these hydrom-
eters are weighted to maintain them in a
vertical position in the liquid.

36. Specific Gravities of Various Substances.
— The following table gives the specific
gravities and the weights per cubic foot of
many common solid and liquid substances.
The weights per cubic foot of most of the
substances in this table are calculated from ^^^'- ^

, . 1 -. ^ • c , f • The Baum6

the weight of one cubic toot 01 water at its Hydrometer
maximum density (39.2° F.), namely, 62.425 pounds.

MINE GASES AND EXPLOSIONS

Table 3
specific gravities and weights of substances

Substance

Average
Specific
Gravity,
Water = 1

Average

Weight, Lbs.

per Cu. Ft.

Alcohol, pure

Aluminum

Asphalt, 1 to 1 .8

Brass, cast, 7.8 to 8.4

" rolled

Coal, anthracite, 1.3 to 1.7 (solid)

" bituminous, 1.2 to 1.5 (solid)

Copper, cast, 8.6 to 8.8

rolled, 8.8 to 9

Gold, cast

Ice

Iron, cast, 6.9 to 7.4, usually assumed . . .

" wrought, 7.6 to 7.9, usually assumed

" rolled, usually assumed

Lead, 11.3 to 11.47

Limestone

Lime, quick

Mercury, 32° F

62° F

Petroleum

Powder, black (blasting)

Platinum, 21 to 22

Sandstone, dry, 2.1 to 2.7

Shale, 2.4 to 2.8

Slate, 2.7 to 2.9

Silver

Steel, 7.7 to 7.9, assumed

Tar

Trap-rock

Tin, cast, 7.2 to 7.5 ...

Water, pure rain or distilled

sea, 1.026 to 1.03

.793

2.66

1.4

8.1

8.4

1.5

1.35

8.7

8.9
19.258
.92

7.21

7.77

7.69
11.38

2.7

1.5
13.594
13.555

8.878
.923
21.5

2.4

2.6

2.8
10.5

7.85

7.35

1.028

49.5
166.

87.4
505.64
524.37

93.64

84.27
543.
555.58
1202.28

57.44
450.
485.
480.
710.4
168 . 55

93.64
848.61
846 . 17

55.42

57 . 62
1342 . 14
150.
162.3
175.
655 . 55
490.

62 . 425
187.27
458 . 82

62.425

64 . 17

37. Difference between Atomic Weight and Specific
Gravity. — The question is often asked, Why is platinum,
whose atomic weight is 194.8, so much heavier than lead,
whose atomic weight is 206.9, platinum weighing 1,342
pounds per cubic foot, while lead weighs but 710 pounds?
The reason is, that like volumes of either solids or liquids
do not of necessity contain the same number of molecules.

SPECIFIC GRAVITY 23

Avogadro's law (Art. 31) is true only of gases; the specific
gravities of gases are, with one or two unimportant excep-
tions, proportional to their molecular weights, or in the
case of simple gases, the specific gravity of the gas is pro-
portional to its atomic weight. But the molecules of
solids are massed together so that the specific gravity of
the solid bears no relation to its atomic weight.

38. The Use of Specific Gravity. — The specific gravity
of a body, solid, liquid, or gas, is the ratio of its weight to
the weight of an equal volume of another body taken as
a standard. Water is usually assumed as the standard for
solids and liquids, and its weight is commonly taken as
62.5 pounds per cubic foot; but when extreme accuracy is
desired the exact weight of water at its maximum density
(39.2° F.) is taken, which is 62.425 pounds. The stand-
ard for gases is air, at the same temperature and pressure.
Knowing the weights of these standards the weight of a
given volume of any solid, liquid, or gas is found by multi-
plying the weight of a cubic foot or the unit weight of the
standard by the specific gravity of the soHd, liquid, or
gas, and that product by the given volume according to
the following :

Rule. — (a) For Solids or' Liquids. — Multiply the unit
weight of water {62.5 lb.) hy the specific gravity of the solid
or liquid, and that product hy its volume; the last product
will he the weight of the given volume of the solid or liquid.

(h) For Gases. — Multiply the unit weight of air, at 33° F.,
har. 29.92 inches {.080728 lb.), hy the specific gravity of the
gas and that product hy its volume; the last product will be the
weight of the given volume of the gas at the same tempera-
ture and pressure.
Or expressed as a formula this rule is

W = {wXG)V (6)

24 MINE GASES AND EXPLOSIONS

TF = required weight of substance (lb.);
w=umt weight of standard (lb. per cu. ft.);
F= volume of substance (cu. ft.);
(j = specific gravity of substance.

Example 1. — Find the weight of 10 cubic feet of bituminous coal
having a specific gravity of 1.27.

Solution. — Substituting the given values in formula 6 the required
weight is

Tr=(62.5X 1.27)10 = 793.75 lb. Ans.

Example 2. — A piece of anthracite coal weighing 15 pounds is found
by trial to displace when immersed an amount of water weighing
exactly 10 pounds; what is the specific gravity of the coal?
-^ Solution. — Since the coal when immersed displaces its own volume
of water, and the specific gravity of the coal is the ratio of its own
weight to the weight of an equal volume of water,

(?=~ = 1.5. Ans.

Example 3. — A piece of limerock weighs 16 pounds in air and but
9.6 pounds when immersed in water; what is its specific gravity?

Solution. — Substituting the given values in formula 1, the specific
gravity of the limerock is

^=Tra=gl = 2.5. Ans.

Example 4. — A certain silver coin weighing 38 grains in the air,
weighed 34.5 grains in water and 35.2 grains in alcohol; calculate the
specific gravity of the alcohol.

Solution. — Substituting the given values in formula 2, the required
specific gravity of the alcohol is

„ 38-35.2 2.8 „ ,
^ = 38^:34:5^3-5 = -^- ^^^-

Example 5. — A glass globe from which the air was first exhausted
weighed empty 1,250 grains; when filled with air at a given temperature
and pressure the weight was 1,268.2 grains; when filled with carbon
dioxide gas, at the same temperature and pressure, the weight of the

CHEMICAL REACTIONS AND EFFECTS 25

globe and gas was 1,277.83 grains; calculate the specific gravity of the
gas.

Solution. — Substituting the given values in formula 3, the required
specific gravity of the gas is .

^ 1,277.83-1,250 27.83 , ^^n . a
^- 1,268.2-1,250 --18T=-^-^^^+' ^^"

Example 6. — Calculate the weight of 100 cubic feet of carbon
dioxide gas at 32° F. and a barometric pressure of 29.92 inches of mer-
cury, calling the unit weight ot air under these conditions ,08073 pound.

Solution. — The weight of 1 cubic foot of air at this temperature
and pressure is .08073 pound, and the specific gravity of carbon dioxide
gas (Table 1) is 1.529, substituting these values in formula 6,

TF = 100 (.08073 XI. 529) = 12.34 + lb. Ans.

Example 7. — Calculate the weight of 1 cubic yard of solid sand-
stone having a specific gravity (Table 3) of 2.4.

Solution. — Taking the weight of a cubic foot of water as 62.5 pounds
and substituting values in formula 6, the weight of 1 cubic yard (27
cu. ft.) of sandstone is

IF = 27 (62. 5X2.4) =4.050 lb. Ans.

CHEMICAL REACTIONS AND EFFECTS

39. If the affinity of the atoms of the different elements
were all equal, there would be no tendency of the atoms
of different substances to change places, and as a result
there would be no such thing as chemical reaction. There
is, however, a great difference in the affinity of certain
atoms for certain other atoms, and this difference of
affinity gives rise to chemical change. The interchange
that thus takes place between the atoms of different sub-
stances is called chemical reaction. Chemical reactions
may be expressed in the form of an equation.

40. Symbols. — To properly express these equations, a
symbol is employed to designate each of the elements
entering into the reaction. Every element is thus ex-
pressed by a symbol. This symbol is usually the first

26 MINE GASES AND EXPLOSIONS

letter of the name of the element, as Hydrogen, H; Oxy-
gen, 0; Carbon, C; or the first letter of the Latin name, as
Potassium {Kalium), K; but where two or more elements
begin with the same letter a second letter is added, as
Calcium, Ca; Copper (Cuprum), Cu; Iron {Ferrum), Fe, etc.
(Table 2.) A symbol standing alone is taken to represent
a single atom of the element; two, three, or more atoms
are indicated by writing small subscript figures, 2, 3, etc.,
after the symbol; thus H, H2, H3 represent respectively
one, two, and three atoms of hydrogen.

41. Chemical Formulas. — A chemical formula is an
expression intended to show the chemical composition of
a molecule of a given substance. It is always expressed
by the symbols of the various elements entering into the
composition of the molecule. The number of atoms of
each particular element present is indicated by a small
subscript figure written after the symbol of such element.
The molecules of most elements in the gaseous form are
assumed to contain two atoms each, and are so represented
in writing the formulas Tor such molecules; thus, H2, O2, N2
represent respectively a single molecule of hydrogen,
oxygen, and nitrogen. Two, three, or more molecules are
indicated by WTiting large figures, 2, 3, etc., before the
symbol representing the molecule; thus, 2H2, 5O2, 6N2
represent respectively two, five, and six molecules of
hydrogen, oxygen, and nitrogen. A compound molecule
may contain any number of atoms greater than one. The
following may be mentioned as examples of molecules
containing different numbers of atoms:

Carbon monoxide (CO), 1 atom carbon, 1 atom oxygen 2 atoms

Carbon dioxide (CO2), 1 atom carbon, 2 atoms oxygen 3 "

Ammonia (NH3), 1 atom nitrogen, 3 atoms hydrogen 4 *'

Methane (CH^), 1 atom carbon, 4 atoms hydrogen 5 "

defiant gas (C2H^), 2 atoms carbon, 4 atoms hydrogen 6 "

CHEMICAL REACTIONS AND EFFECTS 27

The molecules of other substances, particularly organic
bodies, may contain a very large number, sometimes
upwards of 100 atoms. The chemical formula repre-
senting any molecule expresses its composition as deter-
mined by chemical analysis. For example, analysis has
shown that water is composed of 1 part by weight of
hydrogen to 8 parts by weight of oxygen. Since the
atomic weight of oxygen has been determined as 16 and
that of hydrogen 1, the fornmla representing a molecule
of water must contain two atoms of hydrogen and one
atom of oxygen and is therefore H2O. In like manner
the formula for ammonia has been determined as NH3;
sulphuric acid, H2SO4; calcium sulphate, CaS04; olefiant
gas, C2H4, etc. The fornmla representing any substance
is likewise always determined by analysis, and must be
memorized by the student.

42. A Chemical Equation. — Since a chemical reaction is
simply an interchange of the atoms forming the mole-
cules of substances, and results in no loss of matter but
the formation of new compounds, such a reaction may be
expressed by an equation the first member of which
contains the formulas of the substances as they were
before the reaction took place, and the second member
the formulas of the compounds formed by the reaction,
or, as we say, the products of the reaction. It is important
to observe that, since no matter is lost, the total number
of atoms is the same before and after the reaction, and
both members of the equation therefore contain an
equal number of atoms. As previously explained, the
cause of chemical reaction is the greater or less affinity
of different atoms for each other; the reaction is usually
assisted by heat and in most cases by the presence of
moisture. The ease with which chemical reaction takes

28 MINE GASES AND EXPLOSIONS

place varies with different substances. Compounds that
resist chemical reaction to a marked degree are called
stable compounds; others quite susceptible to chemical
change are termed unstable compounds.

The chemical equation expressing any reaction can
only be written when the products of the reaction are
known; hence it is often difficult or perhaps quite impos-
sible to express with exactness some reactions since the
resulting products vary in kind with the conditions under
which the reaction takes place. For example, when
methane (CH4), often called marsh gas, is completely
burned in air the oxygen of the air unites with the car-
bon of the gas to form a new gas, carbon dioxide (CO2),
and with the hydrogen of the gas to form water vapor
(H2O), while the nitrogen of the air remains unchanged.
When, however, there is a limited supply of air present
some carbon dioxide gas will be formed and (Art. 112)
varying amounts of carbon monoxide (CO) and generally
some unburned methane will remain mixed with the nitro-
gen of the air. The relative amounts of these several
products will depend wholly on the conditions attending
the combustion, and it is therefore not possible to rep-
resent this combustion with any degree of exactness.

To write the chemical equation expressing the complete
combustion of methane in air, we first write as below the
formulas for this gas and for air, for the first member of
the equation, and then the formulas for the several
products that we know will be formed by the reaction,
not attempting to express the amount of each; thus,

Methane ^^' Carbon „, ^ -^.

(marsh ga^) Oxygen Nto^ dio^^e Water N.trcgen

CH4 + O2 + N2 == CO2 + H2O + N2

CHEMICAL REACTIONS AND EFFECTS 29

It will be observed that the above equation is not complete,
since both members do not contain the same number of
atoms, there being 9 atoms in the first and but 8 atoms
in the second member. To remedy this trouble we
observe the supply of oxygen must be sufficient to satisfy
both the carbon and the hydrogen of the methane or
marsh gas. Each molecule of this gas contains 1 atom
of carbon and 4 atoms of hydrogen. The 1 atom of
carbon will take 2 atoms of oxygen to form 1 molecule of
carbon dioxide gas; and the 4 atoms of hydrogen will
require 2 more atoms of oxygen to form 2 molecules of
water, consuming in all 4 atoms or 2 molecules of oxygen.
Since, as will be learned later, air contains 4 volumes of
nitrogen to 1 volume of oxygen, there will be 8 molecules
of nitrogen represented in this reaction. The complete
equation will therefore contain 1 molecule of methane,
2 of oxygen, and 8 of nitrogen in the first member; and
1 molecule of carbon dioxide, 2 of water, and 8 of nitro-
gen in the second member, as follows:

CH4 + 202 + 8N2=C02+2H20 + 8N2. ... (7)

Each member of this equation contains the same number
of atoms; it is therefore the complete equation express-
ing this reaction. The nitrogen has played no part in
the reaction further than the dilution of the other gases.

43. The Use of Chemical Formulas and Equations. A
chemical formula shows at once the composition of a sub-
stance. Since the formula represents a molecule whose
molecular weight (Art. 30) is the sum of the atomic
weights of the atoms forming the molecule, and whose
molecular volume (Art. 31), in the case of all the mine
gases and air, is 2, it is possible from the formula to cal-

30 MINE GASES AND EXPLOSIONS

culate the density of any of these gases or of air. To do
this, first find the molecular weight of the gas as follows:

Molecular weight CO, 12 + 16 =28
Molecular weight CO2, 12 +2(16) =44
Molecular weight NH3, 14 + 3(1) =17
Molecular weight CH4, 12 + 4(1) =16
Molecular weight C2H4, 2(12) + 4(1) =28

But the density of a gas is always equal to its molecular
weight divided by its molecular volume, which gives for
the density of each of these gases as follows :

Density CO,

Density CO2,

Density NH3,

Density CH4,

Density C2H4, 2/ = 14.

To calculate the specific gravity of a gas referred to air,
it is first necessary to calculate the weight of a volume
of air corresponding to a molecule of gas. To do this, we
must remember that air is a mechanical mixture and not
a chemical compound; the nitrogen and oxygen gases
that chiefly form the atmosphere are mixed together in
the proportion, by volume, of 4: 1. In other words, every
5 cubic feet of air consists of 4 cubic feet of nitrogen mixed
with 1 cubic foot of oxygen, and it follows directly from
Avogadro's law (Art. 31) that for every 4 molecules of
nitrogen there is 1 molecule of oxygen. Therefore, to
compare equal volumes of gas and air, we must consider
at least 5 molecules of the gas, and find the ratio that
the weight of these 5 molecules of gas bears to the sum
of the weights of the 4 molecules of nitrogen and 1 mole-

-¥

= 14.

= 22.

-V-

= 8.5

= 8.

CHEMICAL REACTIONS AND EFFECTS

cule of oxygen (air). This ratio is the specific gravity
of the gas referred to air at the same temperature and
pressure; thus,

Calculated Specific Gravity

Actual Specific Gravity

5X28 _

.967

4(2X14)+ (2X16) •

5X44 _

1.529

4(2X14)+ (2X16) "" "^

5X17 _

.589

4(2X14)+ (2X16) -^^

^^^^ - 556

.559

4(2X14)+ (2X16) ■

5X28 _

.978

4(2X14)+ (2X16)

CO,

C02,
NH3,

C2H4

The difference between the calculated and the actual
specific gravities of these gases is due to two causes:
(1) Air always contains small quantities of carbon dioxide
gas, ammonia gas, and moisture. (2) The exact propor-
tion, by volume, of the nitrogen and oxygen gases forming
air is (Art. 73) expressed by the ratio 79.1:20.9 instead
of 4 : 1 as stated approximately above.

To calculate the density of air referred to hydrogen as a
standard, we have

4(2X14)+ (2X16)
5(2X1)

14.4.

That is to say, any given volume of air is 14.4 times heavier
than the same volume of hydrogen gas at the same tem-
perature and pressure. Dividing the density of any gas
referred to hydrogen by 14.4 will give the specific gi-avity
of the gas referred to air. For example, the density of
carbon dioxide referred to hydrogen is 22 (Table 1) and

32 MINE GASES AND EXPLOSIONS

:rj-r==1.527S, which is the calculated specific gravity of

carbon dioxide referred to air.

44. Percentage Composition by Weight. — ^The cheraical
formula of any substance— solid, liquid, or gas — expressing
as it does the composition of the substance, makes it pos-
sible to calculate therefrom its percentage composition,
either by weight or by volume. To do this, first find the
molecular weight of the substance, which is the sum of
the atomic weights of its constituents. Then the ratio of
the atomic weights of any of the constituent atoms to
the molecular weight of the substance, multiplied by 100
will give the percentage by weight of that constituent.
For example, a molecule of water (H2O) contains 2 atoms
of hydrogen and 1 atom of oxygen, and its molecular
weight is found thus.

Hydrogen, 2 atoms, atomic weight, 2x1= 2
Oxygen, 1 atom, <^ " 16

Water, molecular weight, 18

Hydrogen, percentage by weight, y2_. X 100 = 1 1 . 1 + %
Oxygen, '' '' " if X 100 -="88.9-%

In like manner, the percentage composition, by weight,
of carbon dioxide (CO2), a molecule of which contains 1
atom of carbon and 2 atoms of oxygen, is as follows :

Carbon, 1 atom, atomic weight, 12

Oxygen, 2 atoms " " 2x16=32

Carbon dioxide, molecular weight, 44

Carbon, percentage by weight, ^J X 100 =27.3 - %
Oxygen, '' " '' iixl00 = 72.7+%

In a similar manner, whenever the chemical equation
expressing a reaction is known, it is possible to calculate

CHEMICAL REACTIONS AND EFFECTS 33

the relative weights of the substances concerned in the
reaction. For example, from equation 7, expressing the
reaction that takes place in the complete combustion
of methane (marsh gas) in air, it is possible to calculate
the weight of air required to completely burn a given
weight of this gas; also, the weights of carbon dioxide and
water formed as a result of the combustion. To do this,
we write again the equation, and underneath this the
relative weight of each constituent; thus,

CH4+2O2+8N2 =C02 + 2H20 + 8N2
Relative weight 16 64 224 44 36 224

The above relative weights are calculated by taking the
sum of the atomic weights of the constituent atoms in
each case, as just explained. The weights thus found
represent the total relative weights of the several constitu-
ents concerned in this reaction. Since the oxygen and
nitrogen in this equation together constitute the air, the
relative weight of the air consumed is 64 + 224=288.
Hence 288 pounds of air are required to completely burn 16
pounds of methane, or the ratio is 18 pounds of air to 1
pound of gas. In like manner it is observed that the com-
plete combustion of 16 pounds of methane produces 44
pounds of carbon dioxide gas and 36 pounds of water in
the form of vapor ; there remains also as a product of this
combustion 224 pounds of nitrogen.

The ratio between the relative weights of any two con-
stituents in this equation is always equal to the ratio
of the actual weights of such constituents. For example,
let it be required to find the weight of carbon dioxide
gas produced by the complete combustion of, say, 100
pounds of methane. The ratio of the relative weights
of these gases in this equation is 44:16, which may be

34 MINE GASES AND EXPLOSIONS

written as a fraction, thus ff ; then, calhng the required
weight of carbon dioxide x, the ratio of the actual weights

of these gases is x : 100, or -^, and

X 44

100 ~ 16'

44
X =7^X100 =275 lb.
lb

In like manner the relative weights of any of the other
constituents may be found from the ratio of their relative
weights in the equation.

Example. — ^What weight of air will be consumed in the complete
combustion of 150 pounds of methane or marsh gas?

Solution. — First write the chemical equation expressing the reaction
that takes place when methane is completely burned in air, and
underneath each constituent write its relative weight, as previously-
explained. Then, calling x the required weight of air, make the
ratio of the actual weights equal to the ratio of the relative weights of
these constituents; thus

and

45. Percentage Composition by Volume. — It has been

explained (Art. 31), as a deduction from Avogadro's law,
that, with few exceptions, all gaseous molecules at the
same temperature and pressure have the same volume.
If we are careful then to write every chemical equation
so as to express each constituent in molecules, the number
of molecules of each constituent will represent its relative
volume. For example, in equation 7, it is observed that

:5o

?88
16'

= fxiao=

= 2,700 lb.

Ans,

CHEMICAL REACTIONS AND EFFECTS 35

1 molecule of methane when completely burned in
air yields 1 molecule of carbon dioxide gas and 2
molecules of water vapor, and 8 molecules of nitrogen,
also, remain from the air; and this combustion required in
all, approximately, 2 + 8=10 molecules of air. Hence
the complete combustion of this gas in air requires prac-
tically 10 volumes of air and produces 1 volume carbon
dioxide gas, 2 volumes water vapor, and 8 volumes of
nitrogen, making 11 volumes in all. There were before
the combustion took place 1 volume of gas and 10 volumes
of air; hence, in this case the reaction itself produced no
change in volume, which is not true of every reaction.

The percentage by volume of any constituent of the
products of a reaction is calculated from the ratio its
molecular volume bears to the sum of the molecular
volumes of all the constituents, in the same manner
as described with reference to percentage by weight, Art.
44. For example, the complete combustion of methane
or marsh gas in air, as expressed by equation 7, yields
1 molecule carbon dioxide, 2 molecules water vapor, and
8 molecules nitrogen, making 11 molecules in all. The
percentage by volume of each of these several constituents
is therefore as follows :

Carbon dioxide, percentage by volume, j^yX100= 9.09+%
Water vapor, " " " y2^Xl00= 18.18+%

Nitrogen, " *' '' xtX 100= 72.73-%

Total, 100.00%

As with respect to the relative weights, so likewise the
relative volumes of any of the constituents may be found
from the ratio of their molecular volumes, in the chemical
equation expressing the reaction that takes place, remem-
bering that the ratio of the molecular volumes of any

36 MINE GASES AND EXPLOSIONS

two constituents is always equal to the ratio of their
actual volumes. For example, let it be required to find
the volume x, of nitrogen, remaining after the complete
combustion of, say 100 cubic feet of methane or marsh
gas. The ratio of the molecular volumes of these gases,
in equation 7, is 8:1, or f, and the ratio of their actual

volumes is a;: 100, or jTr^; and since these ratios are
always equal, we have

_x_ _8

100 " 1'

and

8
X ^ jX 100 ==800 cu. ft., approximately.

In like manner it may be found that the same volume of
methane completely burned in air produces 100 cubic feet
carbon dioxide, 200 cubic feet water vapor, and requires
1,000 cubic feet of air for the combustion.

46. Change of Volume Due to Chemical Reaction.
Chemical reaction is sometimes accompanied by a change
in the volume of the gases, the volume of the gases pro-
duced being greater or less than the volume of the gases
entering the reaction, measured at the same temperature
and pressure. This change of volume, therefore, is not
due to the expansion or contraction of the gases owing to
any change in their temperature (Art. 61) or pressure
(Art. 63), which will be explained later. The change
in volume due to chemical reaction has not thus far been
explained by science; its effect will be better understood,
however, if it is remembered that, in accordance with
Avogadro's law (Art. 31), the volume of gaseous molecules,
at the same temperature and pressure, is the same regard-
less of the number of atoms forming the molecule.

CHEMICAL REACTIONS AND EFFECTS 37

The equations expressing one or two simple reactions
will make this clear. For example, 2 molecules of hydro-
gen and 1 molecule of oxygen in combination form but 2
molecules of water, according to the equation

2H2 + 02=-2H20

It is observed from this equation that 3 molecules of
hydrogen and oxygen gases, representing 3 volumes,
yield in combination but 2 molecules or volumes. This
equation, like all other equations, is founded on experiment,
which has shown that when 2 volumes of hydrogen and
1 volume of oxygen combine they form but 2 volumes of
w^ater vapor. This means that if 2 cubic feet of hydrogen
are mixed with 1 cubic foot of oxygen, making 3 cubic
feet of the mixed gases, and these gases are caused to
unite, there will result from the reaction but 2 cubic feet
of water vapor at the same temperature and pressure.

Or, again, if 2 cubic feet of ammonia gas be confined in
a closed vessel and electric sparks are passed through the
gas for some time, dissociation will take place, and there will
be found in the tube 1 cubic foot of nitrogen mixed with
3 cubic feet of hydrogen, making 4 cubic feet of the mixed
gases in place of the original 2 cubic feet of ammonia gas.
This reaction is expressed by the following equation :

2NH3=N2+3H2

It will be observed that in the complete combustion of
methane in air, as expressed by equation 7, there is no
change of volume due to the reaction, there being 11
volumes of gas and air before and 11 volumes of gas and
vapor after the reaction.

38 MINE GASES AND EXPLOSIONS

47. Calculation of Change of Volume. — If the chemical
equation expressing any reaction be so written that each
substance is expressed as one or more molecules, the num-
ber of molecules of each gas or vapor will indicate its
relative volume. These relative volumes may be written
underneath each substance if desired. Thus the chem-
ical equation expressing the reaction that takes place when
carbon monoxide burns in air may be written as follows:

2CO + 02+4N2=2C02+4N2. . . (8)
Relative volumes, 2 14 2 4

It is observed here that the 7 volumes before the reaction
have been reduced to but 6 volumes after the reaction has
taken place. The reduction of volume in this case is in
the ratio of 7 : 6. If there had been 700 cubic feet of the
mixed gas and air before explosion, there would be but
600 cubic feet of gases remaining after the explosion
measured at the same temperature and pressure.

In a chemical equation the ratio of the relative volumes
of any two gases is always equal to the ratio of their actual
volumes. Thus in the above equation the relative volume
ratio of air to carbon monoxide is 5:2. Suppose it is de-
sired to know the volume x, of air, required to burn 150
cubic feet of this gas. The actual volume ratio is then
x:150; and these two ratios being always equal may be
written

TTK^'o', or o: =150X2 =375 cu. ft.

Example. — How many cubic feet of gaseous products will result
from the explosion of 350 cubic feet of carbon monoxide in air, measured
at the same temperature and pressure?

Solution. — In this case, referring to the above equation, it is seen

CHEMICAL REACTIONS AND EFFECTS 39

that the relative volume ratio of gases produced to those producing
the reaction is 6:7; and, calling the required quantity of gaseous
products X, the actual volume ratio is a;: 350. Hence,

^fr ==r; or, a:=350Xpr = 300cu. ft. Ans.
ooU 7 7

48. Effect of Change of Volume. — The contraction of the
volume that occurs in some chemical combinations of gases
involves necessarily the simultaneous transformation of
some of the latent heat (kinetic energy) of the gases into
sensible heat (Art. 57), being similar in this respect to the
effect produced when the gas is compressed by an external
force. Heat is evolved, but not, however, as the result of
an increase of pressure, the latter remaining constant. The
development of heat accompanies a change of volume in
either case, but when the change of volume is due to a
chemical change the heat comes from internal sources, and
when the change of volume is due to an external force the
heat is due to the transformation of that force.

If the gases are confined, or if the initial pressure at the
moment of the change is considered, there results a change
of pressure owing to the expansion of the gas to fill the
original space occupied. The reduction of pressure in
this case is nearly in the ratio of the contraction of volume.
In other words, the pressure ratio is nearly equal to the
relative - volume ratio. The initial pressure due to the
explosion of carbon monoxide is reduced from this cause
in about the ratio of 6 : 7.

Owing to the heat evolved by the chemical change being
absorbed by the gases the contraction of volume is adia-
batic (Art. 64); the subsequent expansion is also adia-
batic. Hence, calling the original volume of the gases vi
and the contracted volume as shown by the chemical equa-

40 MINE GASES AND EXPLOSIONS

tion expressing the reaction V2, and the original and final
absolute pressures pi and p2 respectively, the exact rela-
tion of these volumes and pressures is expressed by the
formula

.83

(9)

P2^/V2\-

Pi \vi/

Formula 9 will be further explained and its application
shown by example (Art. 64), after a study of heat in
Chapter II.

EXAMINATION QUESTIONS
Specific Gravity

1. Calculate the weight of a block of coal measuring

3 ft. 4 in. long, 2 ft. 3 in. wide, and 16 inches thick, when
the specific gravity of the coal is 1.4. Ans. 875 lb.

2. A piece of alloy is found to weigh exactly 5 pounds
in the air, and when submerged in water its weight is but

4 lb. 6 oz., what is its specific gravity? Ans. 8.

3. To determine the specific gravity of a certain oil, a
flask was first filled with pure water and its weight full of
water was found to be 800 grains; the same flask was then
filled with the oil and its weight when full of oil was 752
grains; what is the specific gravity of the oil? Ans. .94.

4. Find the weight of 250 cubic feet of carbon dioxide
gas, whose specific gravity is 1.529 (Table 1), at a tempera-
ture of 32° F. and a barometric pressure of 30 inches.

Ans. 30.858+ lb.

5. A glass stopper weighs in the air 620 grains, in water
570 grains, and in a certain liquid only 530 grains; what
is the specific gravity of the liquid? Ans. 1.8.

EXAMlNAflON QUESTIONS 41

6. (a) Calculate the specific gravity of sulphureted
hydrogen gas (H2S). {h) What is its actual specific gravity
as determined by experiment? Arts, (a) 1.1805;

(6) 1.1912.
Chemistry

7. Calculate the percentage composition, by weight, of
methane or marsh gas (CH4). Ans. C, 75 per cent.

H, 25 per cent.

8. What weight of oxygen gas will be required to com-
pletely burn 10 cubic feet of carbon monoxide gas, meas-
ured at a temperature of 32° F. and a barometric pressure
of 30 inches? Ans. .446+ lb.

9. (a) Find the weight of 1 cubic foot of oxygen at 32° F.
and 30 inches barometer, (h) What is the volume of the
oxygen gas in the last example, at this temperature and
pressure? Ans. (a) .0892+ lb.

(b) 5cu.ft.

10. (a) Write the chemical formula expressing the re-
action that takes place when carbon monoxide gas burns
in oxygen, (h) What volume of oxygen gas will be re-
quired to consume 10 cubic feet of carbon monoxide gas?

Ans. (a) 2CO + 02=2C02
(6) 5cu. ft.

11. What volume of air will be consumed and what
volumes of carbon dioxide and nitrogen produced in the
complete combustion of 100 cubic feet of methane?

Ans. Air, 1,000 cu. ft.
CO2, 100 '' ''
N2, 800 " ''

12. What is the percentage composition by volume of
the gaseous products resulting from the combustion of
carbon monoxide in air? Ans. CO2, 33 J per cent.

N2, 66f per cent.

CHAPTER II
HEAT AND ITS EFFECTS

49. As previously explained (Art. 27), the term heat
describes a condition or state of matter that can be meas-
ured as energy is measured. It is assumed that this con-
dition or state of matter is one of motion, and that the
sensation imparted by heat is due to the rapid vibration
of the molecules of the heated matter. This hypothesis
is supported by the fact that heat may be converted into
motion and motion into heat, and this exchange is always
effected in a constant ratio by an exact numerical law
that has been fully demonstrated by the careful and elab-
orate experiments of Joule and others.

50. Temperature. — A popular fallacy that is far from
the scientific fact is to regard the temperature of a body
as a measure of the heat it contains. Temperature de-
pends both on the quantity of heat in the body and the
capacity of that body for heat; it is thus a relative term
and not an absolute unit of measure. Temperature is
measured in degrees, which form the units of a thermometer
scale. There are three common thermometer scales known
as the Fahrenheit, Centigrade, and Reaumur scales. For
the sake of comparison, the three scales are shown in Fig. 6,
side by side. Each of these scales is graduated with
reference to two fixed points, which present an invariable
temperature and are readily obtainable. These are the

HEAT AND ITS EFFECTS

temperature of melting ice and that of boiling water (sea level) .
The former or lower reference point registers on the three
scales respectively 32° F., 0° C, and 0° R. ; the latter or higher
reference point registers likewise 212° F., 100° C, and

Fig. 6. — Comparison of Thermometer Scales

80° R. It will be observed that from this arbitrary
marking of the scales 180 degrees of the Fahrenheit
scale correspond to 100 degrees and 80 degrees respectively
of the Centigrade and the Reaumur scales. The ther-

44 MINE GASES AND EXPLOSIONS

mometer in common use consists of a fine capillary glass
tube with a small bulb blown on the lower end. Mer-
cury is introduced into this tube; and after boiling the
mercury to expel all air from the mercury and tube, the
upper end of the tube is sealed. Any change in tempera-
ture is indicated by the expansion or contraction of the
mercury causing the column to rise or fall in the tube.

The following formulas will furnish a ready means of
converting the readings of one scale into the correspond-
ing readings of another scale, and will be understood with-
out further explanation than to say the letters F, C, and
R indicate the respective scale to which the reading is
referred :

F = |C+32; (10)

F ==|i^+32; (11)

C=UF-S2); (12)

R^UF-32); (13)

C=iR; (14)

R=iC (15)

In using the above formulas it is important to notice that
32 is added and subtracted algebraically; that is to say,
when the signs are like the quantities are added together,
their sum taking the same sign; but when the signs are
unlike the lesser quantity is subtracted from the greater,
the difference taking the sign of the greater. Readings
below zero have a minus ( — ) sign, and readings above
zero a plus (+) sign, A few examples will show the use
of the formulas.

Example 1. — Find the Centigrade reading corresponding to 50° F.
Solution. — Substituting the given Fahrenheit reading for F, in
formula 12,

C = |(50-32) = 10°C. Ans.

HEAT AND ITS EFFECTS 45

Example 2. — Find the Reaumur reading corresponding to 23° F.
Solution. — Substituting the given Fahrenheit reading for F, in
formula 13,

i2 = |(23-32)=-4°R. Am

Example 3. — Find the Fahrenheit reading corresponding to 12° C.
Solution. — Substituting the given Centigrade reading for C, in
formula 10,

F = |124-32 = 53.6°F. .4ns.

51. Sources of Heat. — The great natural sources of heat
are the sun, the interior of the earth, and the bodies of men
and animals. The heat from all of these sources, however,
is produced originally by the same causes that generate
artificial heat. ' As a general proposition, the origin of all
heat is energy in one form or another; the energy may be
that due to chemical action or it may be mechanically
developed, but both alike may be converted into heat.
Whenever energy is absorbed or consumed without the
production of mechanical work, heat is the result. A
soft piece of iron may be made red hot by hammering;
two pieces of smooth pine wood may be inflamed by rub-
bing them together; heated journals and cutting-tools
for iron and stone furnish numerous other examples of the
conversion of energy into heat.

52. Heat in Matter, Change of State. — It is now quite
generally assumed that the particles of all matter are in a
state of constant motion, and that this motion imparts
the sensation described as heat and constitutes that con-
dition of matter by virtue of which the quantity of heat
contained may be measured. Bodies are described as being
cold or hot, but these terms are only relative, depending
on the heat capacity of the body, while the quantity
of heat the body contains in any case is an exact amount
that can be measured. It is assumed that no body or

46 MINE GASES AND EXPLOSIONS

substance is wholly devoid of heat, but that all matter
contains a certain amount, however small.

As will' be explained shortly, different kinds of matter
have different capacities for heat, and therefore require dif-
ferent amounts of heat to produce similar changes within
themselves. Different substances pass from a solid to a
liquid state, or from a liquid to a gaseous state, at different
temperatures, though the pressure may remain the same.
Heat and pressure are the principal agents producing such
changes in the form of matter. The melting of ice at
32° F. and the vaporization of water at 212° F., or the
melting of different metals and the vaporizing of differ-
ent substances at numerous temperatures, illustrate the
changes of form produced by heat.

53. Transmission of Heat. — Heat is transmitted from one
body to another or passes from one body into another in
any one of three different ways, by radiation, by conduc-
tion, or by convection. Heat is radiated from a body or
source as light is radiated from a candle, in more or less
straight lines and in every direction; radiant heat, like
light, passes through a vacuum. All bodies thus radiate
heat, but there is a loss of heat resulting in a fall in the
temperature of the body when more heat is radiated than
is received.

Conduction takes place when heat travels from one por-
tion of a solid body to another, or from one body to an-
other with which it is in contact. The rapidity of con-
duction depends on the kind of matter of which the body
is formed, and the quantity of heat transferred depends
further on the time.

Convection takes place only in fluids and is the carrying
of heat from one part to another by the circulation of the
fluid. Thus, the circulation of the water in a steam-

HEAT AXD ITS EFFECTS 47

boiler or that of the heated air in a room distributes the
heat throughout the boiler or the room, as the case may be.

54. Measurement of Heat, Heat units. — The measure-
ment of heat, like the weighing of an atom or estimating
the volume of an atom or molecule, is and can be only
relative to some adopted unit. There are three thermal
or heat units in common use all of which are referred to
water at its maximum density (4° C. =39.2°F.); they are
as follows*:

The British thermal unit (B.T.U.) is a quantity of heat
that will raise the temperature of 1 pound of water 1° F.
at its point of maximum density.

The French unit or calorie is a quantity of heat that will
raise the temperature of 1 kilogram of water 1° C. at its
point of maximum density.

The pound-calorie is a quantity of heat that will raise
the temperature of 1 pound of water 1° C. at its point of
maximum density.

1 r> V I. +u 1 •+ [ '^^^ calorie, or
1 British thermal unit = i ^ ,^ i ^ .

[ 5/9 pound-calorie.

_ I 3.9683 B.T.U., or

[ 2.2046 pound-calories.

, , . ' J 9/5 B.T.U., or

1 pound-calorie =| ^^^^^^^^^-^^

The amount of heat given out from a body is expressed
in terms of one of the above units. This is determined
practically by ascertaining, by careful experiment with
properly constructed apparatus, the exact rise in tempera-
ture of a given weight of water at or near the temperature
of its maximum density. The number of degrees (Fahr.)
rise in temperature of the water multiplied by its weight
(lb.) will be the number of B.T.U. given out by the

48 MINE GASES AND EXPLOSIONS

body. The same quantity of heat will be required to
again raise the body to its original temperature.

55. Mechanical Equivalent of Heat. — The conversion of
heat into energy and energy into heat, which always occurs
in an exact numerical ratio (Art. 49) has led to the expres-
sion mechanical equivalent of heat, by which is meant the
amount of work (foot-pounds) that is equivalent to a single
heat unit (B.T.U.). Experiment has established this value
as

1 B.T.U. = 778 foot-pounds;
or 1 foot-pound = .001285 B.T.U. ;

1 horsepower = 2,545 B.T.U. per hour, nearly.

The mechanical equivalent of heat makes it possible to
determine the amount of heat that will be absorbed in
the performance of any given work.

56. Heat Capacity, Specific Heat. — Different kinds of
matter have different capacities for heat. This is shown
by the fact that when the same quantity of heat is im-
parted to equal weights of different substances, a different
rise in temperature is produced in each substance; and,
again, the same fall in the temperature of different sub-
stances causes them to give out different quantities of heat.
Thus a substance will heat quicker and its temperature
rise higher for the same quantity of heat imparted to it,
as its heat capacity is smaller; and vice versa it will heat
slower and experience a less rise of temperature for the
same quantity of heat imparted, as its heat capacity is
larger.

The heat capacity of a body or substance is measured by
the number of heat units required to raise the temperature
of a unit weight of the substance one degree. If the heat
is estimated in B.T.U. the unit weight is 1 pound and the

HEAT AND ITS EFFECTS

rise in temperature is 1° F.; or, if pound-calorie is used,
the unit weight is still 1 pound, but the rise in tempera-
ture is 1° C. When the heat is estimated in calories the
unit weight is 1 kilogram, and the rise in temperature
1° C. This quantity of heat is called the specific heat of
the substance.

The specific heat of a substance may be defined as the
ratio of the quantity of heat required to raise the tempera-
ture of a given weight of that substance one degree, to the
quantity of heat required to produce the same rise in tem-
perature in an equal weight of water at its maximum
density. It is important to notice that the specific heat of
any substance — solid, liquid, or gas — is the number of
thermal units required to raise the temperature of a unit
weight of that substance one degree.

The specific heats and specific gravities of the more
common mine gases, aqueous vapor, and air are given in
the following table :

Table 4

specific heats of air, mine gases, and vapors
(water =1)

Gas or Vapor

Air

Oxygen

Nitrogen

Hydrogen

Methane

Carbon monoxide. .
Carbon dioxide. . . .
Hydrogen sulphide

Olefiant gas

Aqueous vapor. . . .
Nitrous oxide

Symbol

CH,

CO2

IhS

C,H,

H,0

Equal Weights

Constant

.2374
.2175
.2438
3.4090
.5929
.2450
.2163
.2432
.4040
.4805
.2262

Constant
Volume

.1689
.1548
.1735
2.4260
.4219
.1743
.1539
.1731
.2875
.3419
.1610

Equal
Volumes

Constant
Pressure

.2374
.2405
.2368
.2361
.3314
.2369
.3307
.2897
.3951
.2996
.3450

Specific

Gravity,

Air = l

1 . 1056
.9713
.06926
.559
.967

1.529

1.1912
.978
.6235

1.525

50 MINE GASES AND EXPLOSIONS

The specific heats given in Table 4 are all referred to
water as unity. The specific heat of a gas varies according
as the gas is allowed to expand (constant pressure) or is
confined in a given space (constant volume). When the
gas is allowed to expand, its specific heat is always higher
than when it is confined, owing to the absorption of heat
when the gas expands. These two conditions are referred
to as specific heat under constant pressure, and specific heat
under constant volume. Taking the quantity of heat neces-
sary to raise the temperature of one pound of water at its
maximum density one degree Fahrenheit as unity, the first
two columns of the table show the quantity of heat (B.T.U.)
that will produce the same rise of temperature in an equal
weight of each of the several mine gases for ordinary tem-
peratures. The third column shows likewise the quantity
of heat (B.T.U.) necessary to produce the same rise of tem-
perature in a volume of each gas, equal to the volume of a
pound of air.

The specific heat of gases is not always constant, but
varies with the temperature of the gas, increasing slowly
as the temperature rises. It is stated by some reliable
authorities that the specific heat of carbon dioxide gas at
a temperature of 1,200° F. is practically double that given
in the table. This gas is probably more sensitive in this
respect than any of the other gases. The specific heat of
steam or aqueous vapor increases very rapidly above
212° F. The specific heats of the simple gases and of air
do not increase as rapidly at the higher temperatures. The
specific heats given in the first column of the table for
equal weights and constant pressure are those determined
by actual experiment and given by the most reliable
authorities; they are mostly based on the experiments of
Regnauit. The specific heats given in the second column

HEAT AND ITS EFFECTS 51

of the table for equal weights and constant volume have
been derived by calculation from the specific heats in the
first column for constant pressure by dividing the latter
by 1.405, which is the most generally accepted ratio for
the specific heat of a gas at constant pressure to the specific
heat at constant volume. The figures given in the third
column of the table express the heat capacities of equal
volumes of gas and air at constant pressure instead of
equal weights. These are not, therefore, strictly speaking,
specific heats, although generally so called. The values in
this colunm have been derived by calculation by multi-
plying the specific heats in the first column by the specific
gravity of the gas.

57. Sensible Heat; Latent Heat. — All heat imparted to
bodies does not necessarily produce a rise in the tempera-
ture of the body. Heat imparted to a body causes a
rise in its temperature till a point is reached at which any
further addition of heat is absorbed in producing a molecu-
lar change that results in altering the form of the body,
as explained (Art. 52). Heat that produces a rise in tem-
perature is called sensible heat, while that absorbed in pro-
ducing a change in the body is called latent heat. Latent
heat is again given out and becomes sensible when the body
passes back to its original form or state. The melting of
ice or the vaporization of water is accompanied by an
absorption of the sensible heat of the surrounding air,
whereby the air is cooled. On the other hand, the
condensation of steam or the freezing of water is accom-
panied by a giving out of the latent heat of the steam
and the water that becomes at once sensible in the sur-
rounding air, which is heated thereby. It is this transfer
of heat from water to air and from air to water that
causes the temperature of the atmosphere in the Spring

52 MINE GASES AND EXPLOSIONS

and Fall to apparently become stationary so often at the
point of freezing (32'' F.).

For the present purpose it is sufficient to consider the
quantity of heat (B.T.U.) absorbed or rendered latent by
the melting of one pound of ice at 32° F. to water at 32° F.
and the evaporation of a pound of water at 212° F. to steam
at 212° F.; or, in other words, the latent heat of fusion,
from and at 32° F., and the latent heat of vaporization,
from and at 212° F., the former being 144 B.T.U. and the
latter 966 B.T.U. The total heat absorbed, therefore,
when a pound of ice at 32° F. is converted into steam at
212° F. is, approximately, as follows:

Latent heat of fusion of ice, from and at 32° F. 144 B.T.U.
Sensible heat to raise temperature of 1 lb. of

water from 32° F. to 212° F 180 ''

Latent heat of vaporization of steam, from

and at 212° F 966 "

Total heat per lb., from ice at 32° F. to

steam at 212° F 1,290 B.T.U.

It may be necessary in some instances, in connection
with the conditions incident to mine explosions, to calcu-
late the heat of formation of steam (water vapor) at tem-
peratures higher than 212° F., in which case the formula
of Regnault may be used. This formula gives the number
of B.T.U. necessary to convert one pound of water at
32° F into steam at any temperature t; thus

J5.7^.t/. =1,081.4 +.305^ (16)

Example. — Calculate the total quantity of heat absorbed in convert-
ing 10 pounds of water, at a temperature of 50° F., into steam at
400° F.

HEAT AND ITS EFFECTS 53

Solution. — First find the total heat required to convert 1 pound
water at 32° F. into steam at 400° F., by substituting the given
value for t in formula 16; thus

B.T.C7. = 1,081.4+. 305X400 = 1,203 + B.T.U.
The required heat for 10 pounds of water at 50° F. is thei
10(1,203+ 32-50) = ll,850 B.T.U. Ans.

58. Evaporation, Boiling. — The term ''evaporation"
expresses what takes place at the free surface of a liquid
when it vaporizes or passes from the liquid to the gaseous
state; the boiling or ebuHition of a liquid describes the
formation of vapor rapidly throughout the mass of the
liquid. Evaporation takes place from water, and even
from ice and snow, at all temperatures, but the boiling-
point of pure water for the same atmospheric pressure is
a fixed point (212° F; pressure, 14.7 lb. per sq. in.). Wet
boards steaming in the air, or wet clothes drying in the
wind, are examples of evaporation taking place at all tem-
peratures.

Evaporation at any temperature is always accompanied
by an absorption of heat, which cools the air where the
evaporation is taking place. In a mine the air-current
is thus cooled by the evaporation and warmed by the
condensation of the moisture, which occurs at certain
points in the airway. These phenomena produce im-
portant effects in equalizing the temperature of the air
throughout the mine. The same action going on in a
wet furnace shaft transfers the heat from the bottom to
the upper portion of the shaft, and tends to equalize the
temperature throughout the shaft by the evaporation of
the water in the lower and hotter portion and its con-
densation again in the upjx'r and cooler portion.

54 MINE GASES AND EXPLOSIONS

59. Expansion. — An important effect of heat upon bodies
is the expansion that it causes in the volume of the body.
There is a considerable variation in the amount of expan-
sion of different solids and liquids, but all gases and air
expand and contract according to the same law. The law
of the expansion of gases was first investigated by Gay-
Lussac and Charles, and is known as Gay-Lussac's or
Charles' law. This law established the fact that all gases
and air have the same coefficient of expansion, or, in other
words, expand alike for the same change in temperature,
and this was found to be true for all pressures. The
amount of this expansion was determined with accuracy
later by Regnault, and found to be 1/273 of the volume of
the gas at 0° C. for each degree rise in temperature, of
the Centigrade scale. This is taken to correspond to 1/460
of the volume of the gas at 0°F. for each degree rise in
temperature, of the Fahrenheit scale.

60. Absolute Zero, Absolute Temperature. — It was the
investigation of the law of the expansion of air and gases
by heat, that gave rise to the determination of what is now
known as the absolute zero of the thermometer scale.
This is about 273.3 degrees below zero on the Centigrade
scale ( - 273.3° C), or 460 degrees below zero on the Fahren-
heit scale (— 460°F.). This point of the thermometric
scale is merely a convenient zero point of a scale whose
degrees of temperature will then be always proportional
to the corresponding volumes of air or gas. In other
words, from this point as zero the volume of gas or air
increases in proportion to the temperature. Temperature
reckoned from this point as zero has been called absolute
temperature.

The absolute temperature corresponding to any tempera-
ture of the common scales is found by adding algebraically

HEAT AND ITS EFFECTS 56

273 to any common temperature of the Centigrade scale,
or 460 to any conmion temperature of the Fahrenheit
scale, always regarding temperatures below zero as minus,
and those above zero as plus; thus:

25° C. common temp, is 273 +25 =298° C. absolute temp.
-10° C. '' " "273-10=263°C.

60° F. '' " ^M60+60=520°F. " "

-40° F. " " "460-40=420°F. " "

6i. Relation of the Absolute Temperature and Volume
of Air and Gases. — Considering a given weight of air or gas
at a constant pressure the volume is always proportional
to the absolute temperature of the air or gas. Fig. 7
will assist to make more clear the relation that exists
between the absolute temperature and the volume of
gases. On the left of the figure is a vertical scale of tem-
peratures, expressed both as common and absolute tem-
peratures. From this vertical line is laid off by ordinates
the corresponding volumes of air or gas, for any constant
pressure. For the sake of convenience only, a volume of
460 cubic feet of gas at 0° F. is assumed, and its expanded
or compressed volume is shown at different points of the
scale. It will be observed that the volume of this body
of gas always corresponds to its absolute temperature.
Since the gas expands and contracts, according to Gay-
Lussac's or Charles* law — 1/460 of its volume at 0° F.
for each degree rise or fall in temperature of the Fahren-
heit scale — it would evidently contract to nothing at the
absolute zero, if the gas maintained the same rate of con-
traction at these lower temperatures. It may be assumed,
however, that while Gay-Lussac's law expresses with suffi-
cient accuracy for all practical purposes the rate of expan-
sion and contraction of gases due to their temperature

MINE GASES AND EXPLOSIONS

for all ordinary temperatures, yet there has been observed
at low temperatures sufficient variation from this law to
warrant the belief that the curve of volumes becomes

2 -

672°

560^

360=

160^

-300'

-460

Fig. 7. — Expansion of Air and Gases

asymptote to the vertical at a lower temperature than it
is possible to reach, where further contraction ceases.

The law of the expansion and contraction of air and*
gases, due to a change in temperature, like many other

HEAT AND ITS EFFECTS 57

laws in ventilation, is expressed more concisely and
clearly by ratios; thus:

Rule, — For a constant pressure the volume ratio of any
air or gas is always equal to the absolute-temperature ratio.

Calling any two volumes of the same weight of air or
gas, under a constant pressure, Vi and V2, and their corre-
sponding absolute temperatures, Ti and T2, this rule is
expressed by the formula

?4^ (17)

Vi 1 1

Example. — A volume of 10,000 cubic feet of air per minute is

passing into a mine at a temperature of 10° F.; calculate the expanded

volume of this air-current when it has reached the return airway

where the temperature is 70° F.

Solution. — Calling the required volume x and writing the volume

ratio equal to the absolute-temperature ratio, as expressed by

formula 17,

X 460-1-70 ^ 530.

10,000 "460-1-10 ~470'

53
and a; = 10,000X7= = 11,276-hcu. ft. per min. Ans.

The above relation of temperature and volume con-
siders the air or gas as free to expand under the influence
of the heat absorbed, the pressure remaining constant, if
the air or gas is confined, however, any change in temper-
ature is accompanied with a corresponding change in
pressure.

62. Relation of the Absolute Temperature and Pressure of
Air and Gases. — Considering a given weight of air or gas
having a constant volume, the pressure or tension is
always proportional to the absolute temperature, giving
the following:

Rule. — For a constant volume the pressure ratio of any
air or gas is always equal to the absolute-temperature ratio.

58 MINE GASES AND EXPLOSIONS

Calling any two pressures of the same weight of air or
gas having a constant volume, pi and p2 respective^, and
their corresponding absolute temperatures, Ti and 7^2,
this rule' is expressed by the formula

^=f (18)

The pressure referred to in this rule is the pressure above
a vacuum, or the absolute or total pressure supported by
the gas and which is always equal to the tension of the gas.

Example. — Assuming an original atmospheric pressure (sea level)
of 14.7 pounds per square inch, supported by a body of firedamp
(marsh gas and air) and an original temperature of 60° F., find the
initial pressure, or the pressure at the moment of explosion, when the
temperature has increased to 5,840° F. (Art. 69), there being no
change of volume due to the chemical reaction in this case (Art. 46).

Solution. — Calling the required pressure x and writing the pressure
ratio equal to the absolute-temperature ratio, as expressed by
formula 18,

X ^460 + 5,840^6,300.
14.7 460+60 520 '

315
and X = M.YX-ijTT = 178+ lb. per sq. in. Ans.

63. Relation of the Volume and Pressure of Air and
Gases. — Considering a given weight of air or gas, any
change in the volume is accompanied either with a change
in the pressure or tension of the gas, or a change in
the temperature (Art. 61), or a change both in the pres-
sure and temperature. To determine these changes it is
necessary to consider what caused the change of volume.
Heat imparted to a free body of air or gas causes it to ex-
pand, or if heat be abstracted contraction takes place.
Again, removing the pressure supported by a body of air
or gas causes it to expand, or if the pressure be increased

HEAT AND ITS EFFECTS 59

(compression) contraction takes place. But the expan-
sion of air or gases increases their heat capacity, while
compression decreases the same, as is evident by com-
paring the specific heats of equal weights of air and gases
for constant pressure and volume in Table 4. This change
of heat capacity causes the latent heat to be given out as
sensible heat and the temperature to rise when air or gas
is compressed; but when expansion occurs sensible heat
is absorbed, becomes latent, and the temperature falls.
Thus compression heats while expansion cools a body
of air or gas, and this change of temperature complicates
the relation between the volume and pressure of air and
gases.

Assuming, however, that sufficient heat is added arti-
ficially during the expansion and abstracted during the
compression of the air or gas to maintain the temperature
constant, the pressure or tension will then vary, accord-
ing to Boyle's or Mariotte's law, inversely as the volume,
giving the following :

Rule. — For a constant temperature, the volume ratio of
any air or gas is always equal to the inverse pressure ratio.

Calling any two volumes of the same weight of air or
gas, at a constant temperature, vi and V2, and their corre-
sponding absolute pressures, pi and p2, this rule is expressed
by the formula

^^=^ (19)

Vi P2

This formula may be applied in practically every case in
mine ventilation where a change in volume occurs owing
to a change in pressure, because the change of pressure is
gradual and so sHght that the consequent heating or cool-
ing of the air may be ignored without appreciable error.

MINE GASES AND EXPLOSIONS

Example. — Assuming that an air-space of, say 100,000 cubic feet,
in the abandoned workings of a mine, is filled with a dangerous
mixture of air and gas when the barometric pressure is 30 inches of
mercury; what volume of this gas-laden air will be thrown out upon
the airways by a rapid fall of the barometer to 29.2 inches?

Solution. — In this case, calling the expanded volume of gas and air
X. and writing the volume ratio equal to the inverse pressure ratio, as
expressed by formula 19,

X 30

100,000 29.2'

and

X = 100,000 X 29^ = 102,740 +cu. ft.

The quantity of air and gas thrown off on the airway will therefore
be 102,740-100,000 = 2,740 cu. ft. Ans.

64. Adiabatic Expansion and Compression of Air and
Gases. — When air or gas expands or is compressed without
the addition or loss of heat, the following formulas express
the relations that obtain severally between the volume,
pressure, and temperature. These formulas are useful in
numerous instances, but require the use of logarithms.

Volume and
Temperature

Temperature and
Pressure

Volume and Pressure

V2 (TA 2.469

T, (pA .288

rr \pJ

P2 [TA 3.469
Vi \Tj

^^ /p\.7117

P2_ (vA 1-405 .
Pi U/

An interesting case of adiabatic expansion occurs as
the result of the reduction of volume due to chemical change
explained in article 46. To ascertain whether a reduction
of volume takes place in any given case it is necessary to
write the chemical equation expressing the reaction, and
the relative volumes of the several gases or vapors, as

HEAT AND ITS EFFECTS 61

explained in article 47. Such a contraction of volume
is accompanied with an evolution of heat (Art. 48), the
same as though the air had been compressed. The heat
thus evolved causes a slight expansion, or rather reduces
the amount of contraction that would otherwise occur in
the volume of the gaseous products of the reaction, making

the volume ratio — , in this case { — I , and the final
v{ \Vi/

pressure ratio is then as given by equation (9) (Art. 48):

J) /i,„\ -59X1.405 /i,„\-83

/^Y^^xi-^os^/^x.

Example. — Assuming an original atmospheric pressure of 14.7
pounds per square inch (sea level) and a temperature of 60° F. in the
mine, find the initial pressure due to the explosion of a body of carbon
monoxide and air, at its most explosive point, or when the mixture
consists of 2 volumes of the gas to 5 volumes of air, as shown by
formula (8) (Art. 47), the temperature at the moment of explosion
being 7,405° F. (Art. 69).

Solution. — The first step is to find the increase of pressure due to
the increase of the temperature from 60° to 7,405° F., by substituting
the given values in formula (18); thus, calling the resulting pressure »,

X 460+ 7,405 7,865 ^121,
14.7 ~ 460+ 6a ~ 520 "" 8 '
and

a;= 14.7X^1^ = 222+ lb. per sq. in.

The second step is to fmd the reduced pressure that is the result
of the change in volume due to the chemical reaction (Art. 48). To
do this, again call the required pressure p.^=x and substitute the
value found above pi = 222, and the volume ratio determined by

formula (8) (Art. 47), — = ^, in formula (9); thus,

X /6\-83
222^
and

.83

= 195+ lb. per sq. in. Ans.

62 MINE GASES AND EXPLOSIONS

COMBUSTION

65. In a broad sense combustion is any chemical re-
action accompanied with the evolution of heat, and often
with the production of hght or flame or both. Combus-
tion always involves at least two substances, one of which
is the combustible and the other the supporter of the com-
bustion, the latter being generally a gas. The reaction
that takes place between these two substances is due to
the stronger affinity that exists under certain conditions
of temperature, between certain atoms of the combustible
for certain other atoms of the substance supporting the
combustion. In some cases it requires but a sUght in-
crease in temperature or a sudden jar or shock to start
the reaction. The resulting combustion may be slow or
rapid. Slow combustion produces heat or light, or both,
while a more rapid combustion may be attended with
heat or flame or both of these. When the combustion is
the result of natural causes only it is called spontaneous
combustion. This form of combustion will be considered
in connection with the subject of gob fires.

66. Oxidation is that form of combustion in which the
action is supported by oxygen or air. This includes all
the more familiar forms of combustion, both slow and
rapid. Most of the elements have an affinity for oxygen,
which explains why that element enters most compounds.
Oxygen is the most active element in producing chemical
changes and forming new compounds. A large number of
substances oxidize when exposed to the air; in other
cases the application of heat is necessary to bring about
this change, and in many instances the presence of mois-
ture is necessary to or greatly assists the reaction. The
corrosion of iron and other metals commonly known as

COMBUSTION 63

rusting, the decomposition of carbonaceous matter, the
smoldering of gob fires, as well as the more rapid burning
of coal on the grate, the explosion of gas or powder, etc.,
are all familiar forms of oxidation. The burning of hydro-
gen or phosphorus in chlorine are less familiar forms of com-
bustion; these are not, however, examples of oxidation.

67. The products of a combustion are of two kinds — the
resulting gases and vapors known as the gaseous products
and the solid residue known as the ash. Some of the
gaseous products are condensed to liquids on coohng. The
explosion of ordinary black blasting powder, under the
varying conditions of mining, gives a wide variation in the
products of the explosion and makes it impossible to
express correctly in a single equation the exact reactions
taking place at different times under different conditions.
The extensive series of experiments undertaken by the
British War Department and carried out by Professor Abel,
chemist of the War Department, and Captain Noble, has
shown that when a charge of gunpowder is exploded in a
closed vessel, the fused solid products of the explosion oc-
cupy practically one-third of the space filled by the original
powder and the gaseous products the remaining two-thirds;
and that the volume of the gaseous products measured at
32° F., barometer 29.92 inches, is 280 times the volume
of the original powder, and being crowded into a space
equal to two-thirds of the original volume of the powder,
is equivalent to 280 -^ f = 420 volumes filHng the entire
space occupied by the powder. The temperature resulting
from the reaction being 6,100° F., the confined gases rep-
resent 420 f 4(19/32 ) =5,600 expansions, which at sea

level corresponds to a pressure of 14.7 X 5,600 -^ 2,000= say
40 tons per sq. in.

64 MINE GASES AND EXPLOSIONS

The chemical equation expressing, approximately, the
reaction for gunpowder having the following general com-
position: Nitre, 75 percent.; carbon, 12.5 per cent.; sulphur,
12.5 per cent., may be written as follows :

8OKNO3 +56C2 + 2IS2 =24K2C03 +4K2SO4 + I2K2S + I3S2

Powder Solid products

+40N2 + 64CO2 + 24CO.

Gaseous products

The volume of the solid products of this reaction is about
one-third of the original volume of the powder.

The products of the combustion of nitroglycerin are
wholly gaseous. Bloxam gives the following analysis of
these products: Carbon dioxide (CO2), 37.2 per cent.;
nitrous oxide (N2O), 6.2 per cent.; nitrogen (N2), 12.6 per
cent.; and water vapor (H2O), 44 per cent. The reaction
that takes place at the moment of explosion may be
expressed as follows :

2C3H5(N03)3 =6C02 +N2O +2N2 +5H2O.

The products of the combustion of guncotton in a
closed space are practically all gaseous, there being but
1.85 per cent, of solid residue at the most in a good quahty
of the explosive. The explosion may be expressed in a
typical way by the equation

4Ci2Hi404(N03)6 =24CO + I6CO2 +8CH4 + IONO2 +
7N2 + I2H2O.

The explosion of a known weight of guncotton in a closed
vessel has shown the heat of the combustion to be 1,928
B.T.U, per pound of the explosive. The temperature of

COMBUSTION

the explosion, computed on the basis of the above formula,
is therefore 6,768° F. (Art. 69).

68. Heat of Combustion. — The results of numerous care-
ful experiments have proved that a unit weight of any
given combustible always produces by its combustion the
same quantity of heat, provided the combustion each time
attains the same degree of oxidation, so that it is repre-
sented by the same reaction. This makes it possible to
determine with much accuracy the heating value or calor-
ific power of different combustibles. The values deter-
mined by the experiments of Favre and Silbermann are
generally conceded to be the most reliable, and are given
in the following table as B.T.U. per pound of combustible
burning in oxygen.

Table 5

HEAT OF COMBUSTION OF SUBSTANCES BURNING IN OXYGEN

Combustible

Hydrogen to water at 32° F..

to steam at 212° F

Carbon to carbon dioxide at 60° F. . ,

" to carbon monoxide „. .

Carbon monoxide to carbon dioxide. .
Methane to carbon dioxide and water

at 32°F

Olefiant gas to carbon dioxide and

water at 32° F

Sulphur

Coke, average quality

Wood (dry), average

' ' (wet), average

Coal (anthracite)

' ' (bituminous)

B.T.U.

per Pound
of Com-

Authority

bustible

62,032

Favre and Silbermann

51,717

14,544

4,451

4,325

23,513

21,344

3,996

12,600

7,245

5,580

12,350

Average of

11,930

many tests

The conditions under which the combustion of a sub-
stance takes place determine both the reaction and the
resulting products and therefore the heat of the com-

66 MINE GASES AND EXPLOSIONS

bustion. For the same reaction, however, the amount of
heat developed, or the heat of the combustion, is constant.

69. Temperature of Combustion. — The temperature of
any combustion will always depend on numerous factors
and conditions. Unlike the heat of the combustion the
temperature developed is not constant, even for the same
reaction, but depends largely on the rapidity of the com-
bustion. If the combustion be slow, much of the heat
developed is lost by radiation and the temperature is cor-
respondingly low. For example, the burning of a pound of
carbon to carbon dioxide of a given temperature will always
produce the same quantity of heat (Table 5), whether
the combustion be slow or rapid; but if the combustion
be slow, as in the slow oxidation of fine coal in the gob,
much of the heat is radiated and lost and a low temperature
results ; w^hile in the case of a dust explosion in a mine the
burning with explosive rapidity of the same weight of fine
coal dust suspended in the mine air produces a very high
temperature, approaching and possibly attaining the
theoretical limit. The theoretical temperature of a com-
bustion therefore possesses a practical value in mining,
because it suggests the possibilities of the situation.

The theoretical temperature of any combustion may be
calculated by first writing the chemical equation expressing
the reaction that takes place. The relative weight of each
of the products of the combustion is then calculated for
a unit weight of the combustible, by writing the molecular
weights of the combustible and the several products
of the combustion, and dividing each of the latter by the
molecular weight of the combustible. Then multiply the
relative weight of each of the products of the combustion
by its specific heat (Table 4), using the values for constant
pressure if the gases are free to expand, or for constant

COMBUSTION

volume if they are confined. The sum of the several prod-
ucts thus obtained will be the amount of heat (B.T.U.),
per pound of combustible, required to raise the temperature
of the products of the combustion 1°F. Finally divide the
heat of this combustion per pound of the combustible (Table
5) by the heat required to raise the products of the combus-
tion 1° F., and the quotient will be the rise in temperature
due to the combustion (deg. Fahr.). Adding this to
the original temperature will give the temperature result-
ing from the combustion. The following example will serve
as an illustration in mine ventilation.

Example. — Let it be required to calculate the initial temperature
resulting from the explosion of a body of firedamp (marsh gas and air),
at its most explosive point or when the combustion is complete, as
represented by equation 7 (Art. 42). Find also the number of atmos-
pheres produced by the explosion, or the number of expansions in
the gaseous products resulting therefrom.

Solution. — First write the equation expressing the reaction that
takes place when methane (marsh gas) burns to carbon dioxide and
water, and underneath each substance write its molecular weight and
its relative weight and volume, reducing each to a unit weight of the
combustible; thus:

CH, + 2O2 + 8N2 = CO2+2H2O+8N2

Molecular weight 16 64 224 44 36 224

Relative weight 1 4 14 V^ f 14

Relative volume i 2 8 1 2 8

The relative weight of each of the products of this reaction is then
multiplied by its specific heat to obtain the heat required to raise its
temperature 1° F. The sum of these quantities of heat in the last
column below gives the total heat per pound of combustible required to
raise the temperature of the products of the combustion 1° F. Thus:

Gaseous Products

Specific Heats,
Constant
Volume

Relative Weights

ITeat Required to
Raise Temperature

CO2

.1539 B.T.U.
.3419 ''
.1735 "

11/4
9/4
14

.423225 B.T.U.

H2O

.769275 "

2.429000 "

Total 3.621500 B.T.U.

68 MINE GASES AND EXPLOSIONS

The total heat produced when one pound of methane or marsh
gas burns to carbon dioxide and water at 32° F. (Table 5) is 23,513
B.T.U. From this is subtracted the heat absorbed in converting
water at 32° F. into steam at 212° F., which is 180 + 966 = 1,146 B.T.U.
for each pound of water (Art. 57); and in this case for 9/4 = 2| pounds
there is absorbed 1,146X2^=2,578 B.T.U., leaving 23,513-2,578
= 20,935 B.T.U. as the net heat produced per pound of combustible.
But 3.6215 B.T.U. are required to produce a rise of 1° F., and the
total rise in temperature is then

Total rise in temperature = ^^77^-- = 5,780° F.
3.D215

Assuming the original temperature of the gas as 60° F., the ini-
tial temperature resulting from the combustion will be 60 + 5,780 =
5,840° F. Ans.

In like manner the initial temperature produced when
carbon monoxide burns in air, producing carbon dioxide
and nitrogen, may be calculated and is found to be 7,405° F. ;
showing that this combustion, which is what commonly
takes place in the recoil or the return flame of a mine
explosion, produces a much higher temperature than that
produced by the explosion of methane (marsh gas).

The possible expansion of volume due to any increase
of temperature is shown by the ratio of the absolute tem-
peratures; the volume ratio of the gas being equal to the
absolute- temperature ratio (Art. 61).

In the foregoing example, assuming an original temperature of 0° F.,
the final temperature would be 5,780° F. Then, comparing the expanded
volume of the gas at this temperature with the volume of the gas at
0° F., the volume ratio or the number of expansions in the explosion
of methane (marsh gas) above 0° F. is

Number of atmospheres, explosion of CH4 above 0° F.,
460+ 5,780

460

= 13.56, say 14 atmospheres. Ans.

In each of the above cases the temperature found is the
initial temperature due to the chemical reaction and the heat

COMBUSTION 69

of compression of the gases, and was obtained by taking
the specific heats of the gases for constant volume. To find
the temperature due to the chemical heat only, the specific
heats of the gases for constant pressure must be taken, or the
rise in temperature for constant volume divided by 1.405
will give the rise for constant pressure. The former con-
siders the chemical heat and the heat of compression as
sensible heat, which is true at the initial moment of explo-
sion or whenever the gases are confined; the latter con-
siders the chemical heat only, and may be properly called
the theoretical flame temperature (Art. 122). Thus, for

marsh gas this temperature is i \oc +^Q =4,173° F.; and

7 345
for carbon monoxide ..' , +60 =5,287° F. What is often

called the flame volume of a gas explosion is the number of

volumes or expansions due to the chemical heat, or for

14
marsh gas above 0° F. ^77^ =10 volumes.
° 1 .405

The temperature of combustion, or the temperature of
the gaseous products due to the combustion, must not be
confused with the temperature of ignition of gases, which
will be explained later (Art. 121); the one has no neces-
sary connection with the other.

70. Calorific Power or Heating Value. — The heating
value of a few important gases and other combustibles
have been given in Table 5, expressed in British thermal
units per pound of combustible. This is often spoken of
as the calorific power of a substance or a fuel, for the reason
that the burning of a given weight of any fuel in a given
time will develop a certain power, which is determined by
its heating value. Thus, since one horsepower is equiva-
lent to 2,545 B.T.U. per hour (Art. 55), the total heat

70 MINE GASES AND EXPLOSIONS

of the weight of fuel burned per hour, in any case, divided
by 2,545, will give the theoretical horsepower developed.
For example,

A .u •. mniu u 12,350X100 ,,, ^^
Anthracite, 100 lb. per hr. = — =485 + Hp.

Example. — What is the theoretical horsepower developed by
burning each hour a cord of dry hickory whose heating value is, say
7,000 B.T.U.?

Solution. — Taking the weight of a cord of this wood as 4,500 pounds,
the theoretical power developed is

^^7,000X4 500^^ 3^^^ 4„,

z,o4o

71. Comparison of Fuels. — Dulong, who has carefully
investigated this subject, has given the following formula
for calculating the heating value (B.T.U.) of a pound of
coal from its ultimate analysis :

Heating value per pound=146 0 + 620^--]. . (20)

The letters C, H, and 0 stand for the percentages of car-
bon, hydrogen, and oxygen, respectively. The probable
error in the use of this formula does not exceed 2 per cent.

The presence of sulphur adds 40 B.T.U. for each per
cent, of sulphur present, but this amount is usually so
small as to be of no practical importance and is generally
omitted.

The heating value or calorific power of different fuels
(Table 5) is made the basis on which their comparative
values are determined in practice, as illustrated by the
following examples:

Example 1. — Let it be required to calculate the heating value
of a coal whose ultimate analysis is C 75%, H 5%, O 15%, ash 5%.
Solution. — Substituting the given percentages in formula 20,

Heating value = 1 46 X 75 + 620 (5 —V-) = 12,887 B.T.U. Ans.

COMBUSTION 71

Example 2. — Calculate the amount of energy stored in a single
pound of the coal mentioned in the last example.

Solution. — Since 1 B.T.U. is equal to 778 foot-pounds, the total
energy stored in a pound of this coal is

12,887X778 = say 10,000,000 ft.-lb., or 5,000 ft.-tons. Ans.

Example 3. — How many cords of wood having a heating value of
6,000 B.T.U. will be equivalent to a ton of bituminous coal having a
heating value of 11,500 B.T.U., the wood weighing 4,000 pounds per
cord?

Solution. — Divide the heating value of the coal per ton by the
heating value of the wood per cord; thus,

2,000X11,500 ^^^ , , .
4,000X6,000 =-958+cords. Ans.

The cord of wood in this case is seen to have a slightly greater heating
value than a ton of the coal.

Example 4. — A certain large factory is using as fuel under its boilers
bituminous coal having a calorific power of 2,375 calories, at a cost of
$7.65 per ton. Would it be cheaper to use coke containing 90 per
cent, of fixed carbon and costing $10.50 per ton, and if so what would
be the percentage of gain or saving in fuel expense?

Solution. — Since 1 calorie equals 3.9683 B.T.U. (Art. 54), the heating
value of the coal is 2,375X3.9683 = 9,424 + B.T.U. Again, since the
coke contains but 90 per cent, of fixed carbon, its heat value per pound
of coke would be .9 of the heat value of carbon (14,544 B.T.U.), or
14,544 X .9 = 13,089 B.T.U. The B.T.U. purchased by $1 in each kind
of fuel is then

Coal, M24X|000^2,463,790B.T.U.

7. DO

Coke. 1M89><M00 = 24?2380B.T.U.
10.50

Difference in favor of coke, 28,590 B.T.U.

The percentage of saving is then

28,590

2,463,790

X 100 = 1.16+ per cent. Ans.

72 MINE GASES AND EXPLOSIONS

EXAMINATION QUESTIONS
Heat

1. Convert 5° C. into Fahrenheit degrees.

Ans. 41° F.

2. Convert —10° C. into Fahrenheit degrees.

Ans. 14° F.

3. Convert 17.6° F. into Centigrade degrees.

Ans, -8°C.

4. How many B.T.U. in 1,000 calories?

Ans. 3,968+ B.T.U.

5. How many pound-calories in 810 B.T.U.?

Ans. 450 Ib.-cal.

6. How many B.T.U. are absorbed in raising the tem-
perature of 10,000 cubic feet of dry air from 32^ F. to, say
300° F., in round numbers? Ans. 51,360 B.T.U.

7. If the calorific power of the coal is 12,000 B.T.U.,
how many pounds of this coal will it be necessary to burn
per hour to produce the rise in temperature mentioned in
the last example, in a ventilating current of 10,000 cubic
feet of air per minute passing over the mine furnace?

Ans. 220 lb. per hr.

8. A furnace shaft makes 50 gallons of water each 24
hours, and this water is evaporated, absorbing heat from
the upcast air; what quantity of heat is thus absorbed per
hour if the temperature of the water flowing into the shaft
is 55° F., and the temperature of the air and vapor at the
top of the shaft is 212° F.? Ans. 19,540 B.T.U. per hr.

9. If 50,000 cubic feet of air is passing into a mine at a
temperature of 32° F., what will be the expanded volume
of this current at a point of the return airway where the
temperature has risen to 70° F., neglecting the expansion
due to the decrease of pressure? Ans. 53,861 cu. ft.

EXAMINATION QUESTIONS 73

10. If in the last example the atmospheric pressure was,
say 14 pounds per square inch or 2,016 pounds per square
foot, while the mine pressure in the intake airway was 14
pounds per square foot greater than upon the return air-
way, making the absolute pressure on the intake 2,030
and on the return 2,016 pounds per square foot, to how much
would this decrease of pressure increase the volume of the
return current, in addition to the increase due to tempera-
ture? Ans. 54,235 cu. ft.

11. If in the mine referred to in the last example the
volume of the return current was found to measure 57,500
cubic feet, what volume of gas would this indicate is
being given off in the mine?

Ans. 3,265 cu. ft. per min.

12. If the explosion of ordinary blasting powder pro-
duces 280 volumes of gaseous products, and the remaining
solid products occupy 1/3 of the original volume of the
powder, and it is assumed that the temperature of the
gases at the moment of rupture, owing to the combustion
of the powder not being complete, is, say 2,000° F., the
original temperature before the explosion being 60° F.
and the atmospheric pressure 15 pounds per square inch,
what is thetestimated pressure behind the tamping, and
what is the ruptive pressure acting to break the coal?

Ans. Total pressure, 29,800 lb. per sq. in.

Note. — The ruptive pressure would be 15 pounds less than the
total pressure developed in the hole, but in this case the difference
is insignificant. The ruptive pressure is practically 15 tons per square
inch.

13. How many foot-pounds of energy are stored in a
pound of coal whose heating value is represented by 12,500
B.T.U.? Ans. 9,725,000 ft.-lb.

CHAPTER III
THE ATMOSPHERE.

72. The atmosphere is the gaseous envelope that sur-
rounds the earth and fills all air spaces or cavities open to
its admission.

73. Composition of the Atmosphere.— The gases forming
the atmosphere are chiefly oxygen and nitrogen, with
traces of carbon dioxide, argon, and ammonia and small
varying amounts of moisture. The oxygen of the atmos-
phere is the great supporter of all life, and plays an im-
portant part in almost all chemical reactions; it is the chief
supporter of combustion. The nitrogen of the atmosphere
serves to dilute the oxygen and make it respirable; it is
wholly inert, playing no part in chemical reactions except-
ing to dilute the other gases. It is worthy of note that for
this purpose there is no other gas known that could take
its place and manifest the same inertness to other elements.

The gases of the atmosphere form a mechanical mix-
ture of almost invariable composition. These gases do
not act on each other under any ordinary conditions, or
combine to any appreciable extent in the atmosphere, and
yet they are always found uniformly mixed in the same
proportions, where the oxygen has not been absorbed by
some of the various forms of combustion. Owing to this
constancy of composition, the oxygen and nitrogen gases
of the atmosphere have been called air, as though they

THE ATMOSPHERE 75

formed a compound and were not simple gases. Roughly-
speaking, oxygen forms about one-fifth of the volume and
one-fourth of the weight of the atmosphere or air, and
nitrogen the remainder. The exact proportions in a nor-
mal state of the atmosphere, as given by Dr. Angus Smith
who has investigated this subject, expressed as parts in
100 are as follows :

By Volume By Weight

(Oxygen ,. 20.9 23.0

I Nitrogen 79.1 77.0

100.0 100.0

74. Weight of Air. — At the present time we may say
practically all calculations involving the weight of air are
based upon the careful determinations of Regnault. A
glass globe having a capacity of one litre was weighed
first empty and then filled with dry air at a temperature of
0° C.(32° F.) and a pressure of 760 millimetres (29.92 in.).
The difference made known the weight of the air at this
temperature and pressure. The determination gave the
following results:

1,000 c.c. = 1 litre =1.293187 grams;

1,000 litres -1 cubic metre = 1.293187 kilograms;
1 cubic foot = .080728 pound.

This determination made at Paris (Lat. 48° 50') would
require correction for other latitudes if a spring balance
is to be used; but, in general, it will be sufficient to adopt
as a standard unit, the weight of 1 cubic foot of dry air
at 32° F. and a barometric pressure of 29.92 inches. When
desired the corrected weight of dry air at any place (32° F.,
bar. 29.92 in.) may be calculated, remembering that such

MINE OASES AND EXPLOSIONS

weight is proportional to the force of gravity. For sake
of reference the vahie of the force of gravity is given below
for a few important places and latitudes, at sea level.

Table 6

VALUES OF GRAVITY AT DIFFERENT LATITUDES (SEA LEVEL)

Places

Latitude

Gravity,

Feet per

Second

Places

Latitude

Gravity,
Feet per
Second

Equator

Latitude 45°. .
Poles

0°00'
45° 00'
90° 00'

32.091
32.173
32.255

Paris

48° 50'
51° 29'
40° 30'

32 183

Greenwich. . . .
New York ....

32.191
32.160

The force of gravity varies also with the height above sea
level, diminishing as we ascend. The value of the force
of gravity g (ft. per sec), for any latitude L, and for any
height h (ft.) above sea level may be calculated by the
formula

g = 32.173 - .082 cos 2L - .000003 h . . (21)

Example. — Let it be required to calculate the force of gravity at
Denver, Colorado, having a latitude of 39° 47' N, and an elevation of
5,370 feet above sea level.

Solution. — The cosine of twice the latitude is cos 2(39° 47') = .18109,
and substituting these values in formula 21

^ = 32.173-. 082 X. 18109 -.000003X5,370 = 32.142 ft. per sec. Ans.

75. Formulas for Weight of Air. — Two formulas are in
common use for determining the weight of a cubic foot of
dry air at any given temperature and pressure. The one
commonly used in mining textbooks expresses the pres-
sure in inches of mercury, which is called the barometric
pressure; the other, used in steam engineering practice,
expresses the pressure as pounds per square inch. Owing
to the use of 460 as the absolute temperature instead of
the old value 459, it is necessary to use the constant 1.3273

THE ATMOSPHERE 77

instead of the former constant 1.3253; the results are
practically the same as those obtained by the old formula.
The following formula is used in mining practice:

1.3273 xB . .

^ = -i60Tr^ (22)

in which it; = weight of 1 cubic foot of dry air, at a tem-
perature t and barometric pressure J5 (lb.);
B= barometric pressure or height of mercury

column (in.) ;
^= temperature of the air (deg. Fahr.).

The constant 1.3273 is the weight of a cubic foot of dry
air (lb.) at an absolute temperature of 1° F. (-459° F.),
and a barometric pressure equal to 1 inch of mercury
(standard) (Art. 77), assuming that the laws of the ex-
pansion and contraction of gases (Art. 61) held uniform
at this temperature and pressure and the air retained its
gaseous form.

Example. — Calculate the weight of a cubic foot of dry air at 60° F.
and 30 inches barometer.

Solution. — Substituting the given values in formula 22, the weight
of the air is, in this case,

1.3273X30 39.819 ^^^^^^ ^^^^ „ ,

^== 460+60 =-52^=-^^^^^^' ^^y -^^^^ ^^' ^^*-

The following formula will often be found useful, and
gives practically the same results as formula 22 above:

'^=-;^ (23)

in which, in addition to the symbols previously explained.

78 MINE GASES AND EXPLOSIONS

p = pressure supported by the air (lb. per sq. in.),
T' = absolute temperature of the air (deg. Fahr.).

The constant .37 may be obtained by dividing the weight
of 1 cubic inch of mercury at 32° F. (.4911 lb.) by the
constant used in formula 22; thus

.4911 ^1.3273 = .37

Example. — Calculate as before the weight of a cubic foot of dry air
at 60° F. and a pressure equal to 30 inches barometer.

Solution. — Since 1 cubic inch of mercury weighs .4911 pound, 30
inches of mercury column correspond to a pressure of 30X .4911 = 14.733
lb. per sq. in. Also the absolute temperature is in this case 460+60 =
520° F. Therefore, substituting these values in formula 23

14.733

14 7'?'^

Formulas 22 and 23 are thus seen to give identical re-
sults, but in exact calculations all barometric readings
must be reduced to standard readings, as explained in
Art. 77. It may be desired at times also to correct the
weight obtained by either formula for latitude (Art. 74).
76. Atmospheric Pressure. — The weight of the air form-
ing the atmosphere causes it to press with great force upon
the surface of the earth. The pressure at any point is
equal to the weight of air above that point. At sea level
the average or mean atmospheric pressure is 14.7 pounds
per square inch or 2,116.8 pounds per square foot. This
pressure increases as we descend below sea level and de-
creases as we ascend above sea level. The pressure of the
atmosphere is subject to a regular daily fluctuation, which
though slight attains a maximum between the hours of
9 and 11 a.m. and p.m. and a minimum between the hours
of 3 and 6 a.m. and p.m. There is also a less regular
yearly fluctuation, due mostly to the change in the average

THE ATMOSPHERE

temperature of the seasons and the consequent difference
in the humidity of the air. The yearly fluctuation attains
a maximum in the northern hemisphere in January and a
minimum in July, while the reverse of this is true for the
southern hemisphere. Besides these regular fluctuations
atmospheric pressure is subject to very irregular and often

I 't 't 'If

Fig. 8. — Showing Upward Pressure of the Air

sudden changes by reason of atmospheric storms, the ap-
proach of a storm being accompanied by a fall of pressure.
Air being a fluid like water transmits pressure equally
in all directions; it is not only exerted downwards as
weight, but with equal force sideways and upwards. The
upward pressure of the atmosphere is clearly shown by
filling a tumbler to the brim with water, and placing a

80 MINE GASES AND EXPLOSIONS

piece of fairly stiff paper over the tumbler, in close con-
tact with the water, being careful to exclude all air. The
paper is now held in place while the tumbler is quickly
inverted and held as shown in Fig. 8. As indicated by
the small arrows the upward pressure of the air on each
square inch of the paper supports the weight of the water
above it. The paper simply presents a solid surface to
the pressure of the air.

77. The Mercurial Barometer. — The barometer is an in-
strument for measuring the weight of an imaginary column
of air in the atmosphere. It is constructed on the principle
that the weight of the air column balances and is there-
fore equal to the weight of the mercury column in the
instrument. It consists of a glass tube about 36 inches
long and closed at one end; the tube is filled with mercury,
which is first boiled to expel any air it may contain. The
tube is then inverted, holding the thumb tightly over its
mouth to prevent the escape of the mercury while so
doing, and in this position the mouth is dipped beneath the
surface of mercury in a basin (Fig. 9). When the thumb
is now removed the mercury column in the tube oscillates,
falling and rising, and finally comes to rest with its upper
surface about 30 inches above the surface of the liquid in
the basin, if the experiment is performed at sea level.
The height of the mercury column will be the same what-
ever the area of the cross-section of the tube, since the
mercury column may be considered as taking the place of
an imaginary air column of the same sectional area and
of equal weight, or there would not be equilibrium. The
small arrow-heads, in Fig. 9, represent the pressure of the
atmosphere on each unit area of the surface of the mercury
in the basin, except that occupied by the tube, and here
the weight of the mercury column takes its place. It is

THE ATMOSPHERE

evident that the weight of the mercury column calcu-
lated for an area of 1 square inch will equal the atmos-
pheric pressure per square inch. In round numbers
the atmospheric pressure at sea level, under normal con-

FiG. 9. — Showing Column of Mercury Balanced by the Pressure of
the Atmosphere

ditions, supports a column of mercury 30 inches high,
and taking the weight of 1 cubic inch of mercury as
.49 pound this pressure is

.49X30 =14.7 lb. per sq. in.

In Fig. 10 is shown the form of mercurial barometer
in common use. The glass tube containing the mercury
column is here inclosed in a metal case, with a suitable
opening at its upper end for observing the height of the

MINE GASES AND EXPLOSIONS

mercury.

An adjustable vernier is here provided, that
can be brought by means of the milled-head
screw a to coincide exactly with the top of
the mercury column. Because of the flow of
the mercury from the cistern into the tube,
and from the tube into the cistern at each
rise and fall of the barometer, which
changes the level of the mercury both in
the cistern and in the tube, it is necessary to
adjust the scale to the level of the surface
of the mercury in the cistern before each
reading. This is done in the barometer
shown, as follows: the cistern c is a glass
cylinder to the bottom of which is attached
a bag of chamois skin holding the mercury;
the surface of the mercury can be readily
observed through the glass cylinder. To the
barometer scale is attached a fixed ivory
point projecting downwards, and held in
such a position that its extreme point
coincides precisely with the zero of the
scale. By simply turning the screw b, which
operates against the bag of mercury, the
surface of the liquid can be quickly brought
up or down, so that the ivory point just
pricks its mirrored surface. The scale is then
in adjustment and the vernier is now brought
to the top of the mercury column by means
of the screw a and its reading taken, which
Fig 10 ^^ ^^^ height of mercury supported by the

The Mercurial atmospheric pressure.
Barometer j^ jg necessary that the mercurial barometer

should be placed in a vertical position, and protected from

THE ATMOSPHERE 83

the sun, wind, and weather; it should not be exposed to
the high temperatures of the engine- or boiler-room, but
should be placed where there is a free circulation of cool
air. The thermometer t shown attached to the metal case
of the barometer, Fig. 10, is for the purpose of observing
the temperature when reading the barometer, so as to be
able to correct the reading to a standard reading at
32° F. This is only done when special care is necessary
in comparing readings taken at different temperatures.
The effect of temperature on the reading of the barometer
will be better understood when it is learned that, owing
to the difference between the rates of expansion of the
mercury and the metal case and scale, the barometer will
read one-tenth of an inch higher at 69° F. than the cor-
responding standard reading at 32° F., for the same atmos-
pheric pressure. Without this knowledge an observer,
during a rise of temperature, might suppose the barometer
was stationary when it was actually falling. The proper
formula for the correction for temperature, of any par-
ticular barometer, will be furnished by the makers. It is
preferable that all barometric readings should be reduced
to standard readings before being recorded. Barometric
readings are often spoken of as inches of barometer, or
inches of mercury, or barometric pressure, all referring to
the height of mercury column supported by the pressure
of the atmosphere.

78. The Aneroid Barometer. — The aneroid is an instru-
ment devised as a substitute for the mercurial barometer
for field and for mining work, being a portable form of
barometer. It consists of a metal case fitted with a
graduated dial or face protected by a glass, and having
a single index-hand or pointer, as shown in Fig. 1 1 . Within
this metal case is a flat, round vacuum box, whose top

MINE GASES AND EXPLOSIONS

is corrugated in concentric rings, so as to be the more sen-
sitive to changes of atmospheric pressure. The air has been
partly exhausted from this box the top of which is sup-
ported against collapse by a strong steel spring attached
to its center. The movements of this spring up and

Fig. 11. — The Aneroid Barometer
down, caused by the changes in atmospheric pressure, are
communicated to the index-hand of the dial by a series
of multiplying levers and a fine chain that winds about
a central drum whose axis carries the pointer or hand.
This instrument has been compensated for changes in tem-
perature and graduated to correspond to the readings of
the mercurial barometer. Two concentric scales mark the

THE ATMOSPHERE 85

dial of the mining aneroid; the inner scale reads inches
of mercury, while the outer scale reads feet of elevation
above sea level. The divisions of the mercury scale usu-
ally indicate .02 inch, those of the altitude scale 10 feet.
By means of the vernier shown in the figure, and which is
operated by the milled-head screw, the altitude scale can
be read to single feet. Although 31 inches is not the
mean or average reading of the barometer at sea level,
yet the zero of the altitude scale when fixed is made to
correspond to this reading for convenience of computing
elevations. Since this reading (31 in.) is in general the
highest reading obtained at sea level, any corrections that
may be necessary will generally be in the same direction;
moreover, tables prepared for the purpose of comparing
elevations with average barometric readings usually start
from 31 inches at sea level.

The range of the aneroid barometer is necessarily limited,
and for this reason the scale of the instrument is made to
suit any desired purpose and use, at different altitudes.
Mining aneroids for use at lower elevations are graduated
from, say 33 to 27 inches of mercury, corresponding
approximately to elevations ranging from 2,700 feet below
to 2,800 feet above sea level. For mining work at higher
elevations, or for surface work in coast regions, the scale is
made to read from, say 30 to 24 inches of mercury, allow-
ing an altitude range from the coast to about 6,000 feet
above the sea. For mountainous regions other scales are
adopted to suit the elevation, instruments being con-
structed to read to 20,000 feet above sea level, but at some
sacrifice of accuracy.

79. Use of the Barometer. — The intelligent use of the
barometer is of great importance in mining. Danger often
lies in the misuse of any instrument, and the barometer is

86 MINE GASES AND EXPLOSIONS

no exception to this rule. The relation that exists, if any,
between barometric changes and the occurrence of mine
explosions will be considered later (Art. 141). The pri-
mary purpose of the barometer is to determine the atmos-
pheric pressure at any time and place. The height of the
mercury column is the index of this pressure, but, owing to
the change in the density of the mercury at different tem-
peratures, this height to be a true index must be cor-
rected for temperature; and in our treatment of the sub-
ject it will be assumed that all barometric readings are
standard readings, or have been reduced to standard read-
ings at 32° F. This being the case, the atmospheric pres-
sure corresponding to any barometric reading is found by
multiplying the reading (inches of mercury) by the weight
of 1 cubic inch of mercury at 32° F., which is .4911 pound.
Thus the standard barometric reading under normal
atmospheric conditions at sea level is assumed as 29.92
inches, and the exact atmospheric pressure corresponding
to this reading is, therefore,

29.925 X. 4911 =14.696 + lb. per sq. in.

Either the atmospheric pressure or the barometric read-
ing or pressure is used in calculating the weight of a cubic
foot of air, as previously explained, and this unit weight of
air is used to find the pressure due to any air column.

8o. Atmospheric Pressure and Barometric Readings at
Different Elevations. — The variation of atmospheric pres-
sure with respect to the elevation, either above or below
sea level, and its effect on the density of the air is of
the greatest importance to the subject of mine ventilation.
Table 7 shows at a glance the mean or average pressure
and standard barometric reading (32° F.), at different

THE ATMOSPHERE 87

elevations, together with the unit weight or weight per
cubic foot of air at such elevations and for different tem-
peratures. The table is not only useful in suggesting the
effect that changes of elevation and temperature have on
the efficiency of ventilating fans by altering the density of
the air, but shows clearly to what extent elevation affects
the efficiency of air columns and mine furnaces. It should
be remembered also that the same effects are produced by
changes of the barometer at the same "place. The condi-
tions with respect to the weight of air and pressure of the
atmosphere are true for any corresponding barometric read-
ings, whether at sea level or any other elevation. As given
in the table, the readings represent more or less closely
what is the mean or average reading for each corresponding
elevation, reduced to a standard reading at 32° F.

The mercury readings given in Table 7 have been calcu-
lated for the different elevations by means of the formula

£.=29.92[l±jgi^]\ . . . (24)

in which 5;i=height of barometer at any elevation h (in.);
A = elevation of place above or below sea level

(ft.);
T =average absolute temperature of air column
from sea level to elevation h (deg. Fahr.).

In formula 24 the sign ± relates to the elevation h as
being either above ( — ) or below ( + ) sea level. It is a
difficult matter to obtain even a fair approximation to the
average temperature of an atmospheric column, since the
temperature does not fall regularly, especially when
ascending above sea level. Numerous causes affect the
temperature of the upper atmosphere, chiefly air-currents,

MINE GASES AND EXPLOSIONS

Table 7
effect of elevation" on pressure and density of air

Eleva-
tion,
Feet

25,000

20,000

15,000

14,000

13,000

12,000

11,000

10,000

9,000

8,000

7,000

6,000

5,000

4,500

4,000

3,500

3,000

2,500

2,000

1,500

1,000

900

Barom-
eter,
Inches

800 29
700 29
600 29
50029
400 29
300 29

200
100
Sea to
level r"
- 500
-1,000
-1,500
-2,000
-2,500
-3,000
-3,500
-4,000
-4,500
-5,000

29
29
29
30.
31.
31.
32.
32.
33.
33.
34.
35.
35.

.343
.874
.948
.626
.328
.053
.805
.582
.392
.229
.088
.975
.890
.360
.837
.322
.813
.315
.824
.339
.861
.966
.072
.178
.296
.390
.496
.603
.710
.818
925
.469
022
582
151
727
312
903
504
113
730

Atmos-
pheric
Pres-
sure,
Lbs. per
Sq. In

5.571

6.814
8.323
8.656
9.000
9.357
9.726
10.107
10.505
10.916
11.339
11.774
12.224
12.455
12.689
12.927
13.169
13.415
13.665
13.918
14.174
14.225
14.277
14.329
14.387
14.433
14.486
14.538
14.591
14.643
14.696
14.963
15.235
15.510
15.789
16.072
16.359
16.650
16.945
17.244
17.547

Temperature, Deg. (Fahr.)

•20

32 60 100 200 300 400

Weight of Dry Air, Pounds per Cubic Foot

.0342

.0418

.0511

.0532

.0553

.0575

.0597

.0621

.0645

.0670

.0696

.0723

.0751

.0765

.0779

.0794

.0809

.0824

.0839

.0855

.0871

.0874

.0877

.0880

.0884

.0886

0890

0893

0896

0899

0903

0919

0936

0953

0970

0987

1005

1023

1041

1059

1078

.0327

.0400

.0489

.0509

.0529

.0550

.0571

.0594

.0617

.0641

.0666

.0692

.0718

.0732

.0745

.0759

.0774

.0788

.0803

.0818

.0833

.0836

.0839

.0842

0845

0848

0851

0854

0857

0860

0863

0879

0895

0911

0928

0944

0961

0978

0996

1013

1031

.0306
.0373
.0457
.0475
.0494
0514
.0534
.0555
.0577
.0600
.0623
.0647
.0671
.0684
.0697
.0710
.0723
.0737
.0751
.0764
.0778
.0781
.0784
.0787
.0790
.0793
.0796
.0799
.0801
.0804
.0807
0822
0837
0852
0867
0883

0915
0931
0947
0964

.0290
.0354
.0433
.0450
.0468
.0486
.0505
.0525
.0546
.0567
.0589
.0612
.0635
.0647
.0659
.0672
.0684
.0697
.0710
.0723
.0737
.0739
.0742
.0745
.0748
.0750
.0753
.0756
.0758
0761
.0764
0778
0792
0806
0821
0835
0850
0865
0881
0896
0912

.0269
.0329
.0402
.0418
.0434
.0452
.0469
.0488
.0507
.0527
.0547
.0568
.0590
.0601
.0612
.0624
.0635
.0647
.0659
.0672
.0684
.0686
.0689
.0691
.0694
.0696
.0699
.0702
.0704
.0707
.0709
.0722
0735
0749
0762
0776
0790
0804
0818
0832
0847

.0228
.0279
.0341
.0354
.0369
.0383
.0398
.0414
.0430
.0447
.0464
.0482
.0500
.0510
.0520
.0529
.0539
.0549
.0559
.0570
.0580
.0582
.0585
.0587
.0589
.0591
.0593
.0595
.0597
.0600
.0602
.0613
0624
0635
0647
0658
0670
0682
0694
0706
0719

.0198
.0242
.0296
.0308
.0320
.0333
.0346
.0359
.0374
.0388
.0403
.0419
.0435
.0443
.0451
.0460
.0468
.0477
.0486
.0495
.0504
.0506
.0508
.0510
.0512
.0513
.0515
.0517
.0519
.0521

.0523

.0532
0542
0552
0561
0572
0582
0592
0603
0613
0624

.0175

.0214

.0262

.0272

.0283

.0294

.0306

.0318

.0330

.0343

.0356

.0370

.0384

.0391

.0399

.0406

.0414

.0422

•0429

.0437

.0445

.0447

.0449

.0450

.0452

.0454

.0455

.0457

.0458

.0460

.0462

.0470

.0479

.0487

.0496

.0505

.0514

.0523

.0533

.0542

.0551

THE ATMOSPHERE

radiation from the earth, and hygrometric conditions in
the air. It is sometimes assumed that the average tem-
perature between two elevations is half way between the
respective temperatures at those elevations. A closer
average is obtained however by observing (Table 8) the

Table 8
average temperatures of air columns

For Calculating the Mean Barometric Pressure at any Elevation above

Sea Level, Deduced from Observed Mean temperatures at Different

Elevations

Elevation above
Sea Level, Feet

Mean Observed
Temperature,
Deg. (Fahr.)

Rate of Fall per
1,000 Feet,
Deg. (Fahr.)

Estimated Average

Temperature of

Air Column,

Deg. (Fahr.)

25,000

1.6

20,000

1.8

15,000

2.0

10,000

2.5

8,000

3.0

5,000

3.5

3,000

4.0

scale of mean thermometric readings drawn from the
recorded aeronautic observations of Gay-Lussac, James
Glaisher, John Herschel, and others. The scale is only
suggestive as to the rate of fall in temperature per thousand
feet of rise above sea level. Opposite each elevation is
written, in the second column, a mean observed temperature
for that elevation, and in the third column, the drop or fall of
temperature per thousand feet of rise. In a fourth column
is given the average temperature of the air column reach-
ing from sea level up to each elevation. These average
temperatures have been calculated by finding the weight
of each section of the entire air column separately, and
dividing their sum by the elevation, which gives the

90 MINE GASES AND EXPLOSIONS

average weight of a cubic foot of the air forming that
column; and from this average weight the average tem-
perature of the fourth column was readily found for the
purposes of calculation.

By substituting the above estimated, average tempera-
tures of air columns above sea level, in formula 24, the
mean barometric reading for any corresponding elevation
may be calculated; for any intermediate elevation the
average temperature may be found by interpolation.

Example. — Calculate the mean barometric reading for an elevation
of 10,000 feet above sea level.

Solution. — The mean observed temperature (Table 8) at this
elevation is 27° F., and the average temperature of air column extend-
ing from sea level up to this elevation, estimated as previously ex-
plained and as given in the fourth column of Table 8, is 42° F. The
corresponding absolute temperature is 460 + 42 = 502° F. Substituting
this value for T in formula 24

r 1 -110,000

^*-^H^-144x.37x502] -20.582 m. Ans.

Note. — In the use of formula 24 a table of seven-place logarithms
must be employed.

8 1. Effect of Gravity on Barometric Pressure. — Any

increase or decrease in the force of gravity due to the lati-
tude of the place or its elevation above sea level affects
equally both the mercury and the air column, which are in
equilibrium, and there is therefore no change in the barom^
eter from this cause. Hence the height of the mercury
column reduced to a standard reading (32° F.) is an absolute
unit of measure for atmospheric pressure at all latitudes
and elevations. All properly compensated aneroid barom-
eters are calibrated to give standard readings (32° F.) at
all temperatures, but like the spring balance the readings
of the aneroid vary with the force of gravity.

THE ATMOSPHERE 91

When a barometric reading (inches) is converted into
pounds per square foot, as in Article 79, a unit is
employed that is dependent on the strength of the force
of gravity, and such an expression is not therefore an
absolute unit of measure. To properly define these units
the word standard, in this connection, will be used to indi-
cate a barometric reading reduced to an equivalent stand-
ard reading at 32° F. in accordance with Article 77, or a
pressure (lb. per sq. ft.) based on the determination of the
weight of air at Paris (Art. 74). It is a slight incon-
sistency to take the weight of a cubic foot of air at 32° F.
(.080728 lb.), as determined for sea level at Paris, where the
force of gravity is 32.183 feet per second, and elsewhere use
the value given for gravity at New York (32.16 ft. per sec.) ;
but as these values are so generally adopted no change will
be made in them.

82. Measurement of Pressure in Atmospheres. — It is
often convenient to speak of an observed pressure as
being so many atmospheres, meaning one, two, or three,
etc., times the pressure of the atmosphere at the place
of observation. Air compressed to two, three, four, etc.,
atmospheres is regarded as being capable of the same
number of expansions, this being true at all elevations.
An atmosphere so regarded is a relative and not an abso-
lute unit of measurement. The term atmosphere is some-
times construed to mean a pressure of 14.7 pounds per
square inch, or atmospheric pressure at sea level, but this
is not logical. An atmosphere can only be made a definite
unit of measurement by stating the elevation or giving the
barometric reading or pressure at the place of observation.
It is necessary to remember that the volume of any given
weight of air or gas is reduced in the same ratio as the
number of atmospheres supported.

92 MINE OASES AND EXPLOSIONS

83. Moisture in the Air. — Atmospheric air is never ab-
solutely dry. The condition of the air with respect to
the amount of moisture contained, as compared with the
amount the same air would contain if completely satu-
rated, is called its hygrometric condition, or its degree of
saturation. The capacity of air to hold moisture in-
creases with its temperature. That is to say, the quantity
of moisture required to saturate a given volume of warm
air is much greater than that required to produce satura-
tion in the same volume of air at a lower temperature,
whatever the barometric pressure. For the same reason
comparatively dry air in summer may often contain a much
greater weight of water vapor per unit volume than very
damp or moist air in winter. It is therefore important to
remember that it is not the actual weight of water con-
tained in a given volume of air that determines its humidity
or hygrometric condition but rather its approach to satu-
ration, or the limit of the capacity of the air to hold
moisture. It is clear from this that air that is not satu-
rated may be brought to a state of saturation by a fall
of temperature, but the same air will not then contain any
more water vapor than before. By a further fall of tem-
perature a portion of the moisture may be deposited as
water or rain, because the capacity of the air at this
lower temperature is insufficient to hold the original
quantity of moisture as vapor. In mines such a deposit of
moisture is often witnessed on the roof and side walls
or on the timbers of an airway where a warm current of
air returning from the mine becomes suddenly chilled by
contact with the cooler strata or colder air from the out-
side. In the fan drifts of large exhaust fans it is not
uncommon in the winter season to find a very heavy
downpour of rain produced by the condensation of the

THE ATMOSPHERE 93

moisture when the warm return air of the mine strikes
the cold sheet-iron plates that cover the drift and which
are exposed to the cold outer atmosphere.

Contrary to general expectation, the weight of air per
cubic foot decreases as its degree of saturation increases.
In other words, moist damp air, not to say jog, but air
approaching saturation, is lighter, volume for volume, than
dry air at the same temperature and pressure. The rea-
son for this will be better understood when it is remem-
bered that water vapor is a gas much lighter than air, its
specific gravity being .6235 (Table 4). This gaseous vapor
mixes with the air as another gas, making the mixture of
air and vapor lighter, bulk for bulk, than the original air.
However, the mixture of gases and vapors differs mater-
ially from the mixture of gases only, as will be seen by the
following laws, which are true for all such mixtures :

1. The pressure and consequently the weight of vapor that
saturates a given space at a given temperature are the same,
whether that space is a vacuum or contains gas or air.

2. The pressure of a mixture of a vapor with gas or air is
equal to the sum of the pressures that each would have if
filling the same space alone.

3. For any given temperature there is a fixed limit to the
pressure of a vapor, and therefore a corresponding limit to
the weight of that vapor that will saturate a given space.

4. The pressure and quantity of vapor contained in a non-
saturated space or volume of gas or air is always proportional
to the degree of saturation.

Table 9 gives the pressure of aqueous vapor at the point
of saturation and the corresponding mercury column, for
different temperatures. The pressure of the vapor for any
other degree of saturation is found by multiplying the
values given in the table by the degree of saturation.

94 MINE GASES AND EXPLOSIONS

84. Weight of Moist Air. — The weight of moist air is
calculated by first finding the weight of the same volume of
dry air at the given temperature, but under a pressure
equal to the given pressure less the pressure of the vapor
at the given temperature. The weight of the moisture is
then found separately by finding the weight of the same
volume of dry air at the same temperature, but under a
pressure equal to that of the vapor at such temperature,
found from Table 9; the weight thus found is multiplied
by the specific gravity of the vapor (.6235), and the prod-
uct is the weight of the vapor contained in the air. The
weight of this vapor is then added to the first weight of
dry air to obtain the required total weight of moist air.
The operation is expressed by the following formula,
derived from formula 23:

v — cd) ^ c(h

.S7T -—".377^^
which readily reduces to the form

.=2Z^^. . (25)

In like manner from formula 22 is derived

1 S27S
i^ = -^y-(B-. 3765c v^) (26)

In the above formulas, besides the symbols already ex-
plained,

c= degree of saturation expressed as a decimal;
([f = pressure of vapor of saturation (lb. per sq. in. — formula
25); or (in. of mercury — formula 26).

THE ATMOSPHERE-

Table 9

PRESSURE (tension) OF AQUEOUS VAPOR

fIS?.^'

Barometric
Pressure,
Mercury

(32° F.) In.

Pressure,
Pounds per
Square Inch

Degrees,
Fahr.

Barometric
Pressure,
Mercury

(32° F.) In.

Pressure,
Pounds per
Square Inch

-30

.0099

.0049

.7335

.3602

-20

.0168

.0082

.7587

.3726

-10

.0276

.0136

.7848

.3854

.0439

.0216

.8116

.3986

.0551

.0271

.8393

.4122

.0691

.0339

.8678

.4262

.0865

.0425

.8972

.4406

.1074

.0527

.9275

.4555

.1397

.0686

.9587

.4708

.1815

.0891

.9906

.4865

.1961

.0963

1.024

.5027

.2122

.1042

1.058

.5194

.2205

.1083

1.092

.5365

.2293

.1126

1.128

.5542

.2382

.1170

1.165

.5723

.2476

.1216

1.203

.5910

.2574

.1264

1.243

.6102

.2674

.1313

1.283

.6299

.2777

.1364

1.324

.6502

.2885

.1417

1.367

.6711

.2995

.1471

1.410

.6925

.3111

.1528

1.647

.8090

.3229

.1586

100

1.918

.9421

.3352

.1646

105

2.227

1.0938

.3478

.1708

110

2.578

1.2663

.3610

.1773

115

2.977

1.4618

.3745

.1839

120

3.427

1.6828

.3885

.1908

125

3.934

1.9318

.4030

.1979

130

4.504

2.2119

.4178

.2052

135

5.144

2.5261

.4333

.2128

140

5.859

2.8774

.4492

.2206

145

6.658

3.2696

.4657

.2287

150

7.547

3.7063

.4826

.2370

155

8.535

4.1914

.5001

.2456

160

9.630

4.7292

.5183

.2545

165

10.841

5.324

.5370

.2637

170

12.179

5.981

.5561

.2731

175

13.651

6.704

.5760

.2829

180

15.272

7.500

.5964

.2929

185

17.050

8.373

.6176

.3033

190

18.954

9.330

.6394

.3140

195

21.130

10.377

.6618

.3250

200

23.457

11.520

.6850

.3364

205

25.993

12.765

.7086

.3481

212

29.925

14.696

96 MINE GASES AND EXPLOSIONS

Example 1. — ^In Table 7 the weight of 1 cubic foot of dry air at
sea level and a temperature of 60° F. is given as .0764 pound, find the
weight of this air when saturated with moisture.

Solution. — The an being completely saturated, the hygrometric
state is expressed as 100 per cent., or c = 1 ; at a temperature of 60° F.
the pressure of the vapor of saturation (Table 9) is .2545 pound per
square inch; at sea level the mean atmospheric pressure (Table 7)
is 14.696 pounds per square inch. Substituting these values in
formula 25

14.696-.3765(.2545) „^^^ „ .
^= .37(460+60) =-07588 lb. Ar..

Example 2. — Find the weight of a cubic foot of air, under normal
atmospheric conditions, at an elevation of 10,000 feet above sea level,
when the hygrometric condition of the air is expressed as 62 per cent.,
or c = .62, and the temperature is 32° F., using formula 26.

Solution. — Taking the values of B and ^ from Tables 7 and 9
respectively, and substituting these and the given values in formula
26, the required weight of 1 cubic foot of air under the given condi-
tions is

«, = ±i2±i2(20.582-.3765X.62X.1815) = .05541 lb. Ans.

85. Measurement of the Moisture in the Air. — The

hygrometric condition of the air is determined by a small
instrument called an hygrometer, of which there are
numerous forms capable of a greater or less degree of
accuracy. The form in most common use (Fig. 12) is
that first suggested by Leslie, but often called Mason's
hygrometer. It is a portable, simple instrument, consist-
ing of two delicate thermometers attached to a single
frame, and sometimes provided with a small tube fastened
between them for holding water. The bulb of one of the
thermometers is covered loosely with thin muslin, which is
allowed to hang down so that it dips into the water, and is
kept moist by the water it absorbs from the tube, or it
may be wet by water poured on the muslin. The hygrom-
eter depends on the principle that the evaporation of mois-

THE ATMOSPHERE

ture from any wet surface is more rapid and the consequent
absorption of heat greater in proportion as the air is less
saturated with moisture. The evaporation from the
mushn cools that bulb in proportion as the degree of satura-
tion of the air is less, and the difference in the readings of
the two thermometers is thus made the basis for the calcu-
lation of the degree of saturation of
the air.

CalUng the degree of saturation of
the air c, and the maximum pressure
of the vapor of saturation Fi, at any
temperature h (Table 9), and that at
any temperature t2, F2] the actual
pressure of the vapor in the air at
these temperatures is cFi and CF2
(Art. 83). A formula in common use
for calculating the actual pressure of
the aqueous vapor in the air from the
readings of the hygrometer is the
following :

cF,=

(27)

Fig. 12. — Leslie's or
Mason's Hygrometer

It is evident that dividing both mem-
bers of this equation by the pressure
of the vapor of saturation {F{) will give the degree of
saturation c, which is sought. The constant 88 relates
to the specific heats of air and aqueous vapor and may be
used for all temperatures above 32° F., but for tempera-
tures below 32° F. the constant 96 should be used.

Example. — Calculate the degree of saturation of the air when the
readings of the dry- and wet-bulb thermometers are 60° and 55° F.

MINE GASES AXD EXPLOSIONS

respectively, the barometric pressure at the time and place of obser-
vation being 28 inches.

Solution. — The pressures of the vapor of saturation (Table 9), for
the given temperatures, are 7^60=. 51 83, and F55=.4333. Substituting
these and the given values in formula 27, the actual pressure of the
vapor in the air at 60° F. is

cF.^ = A333 3^^ gg

_ 28/60 -55'

) =.3803;

then

c = |f^ = .73, or73%. Ans.

A new and useful form of hygrometer is now manufac-
tured* called the hygrodeik, in which the dry and wet

thermometers are attached
to an expanded fan-shaped
frame. By means of an
ingenious chart consisting
of a series of cross lines
arranged between the two
thermometers the degree
of saturation of the air can
be read at once for any
readings of the dry and
wet bulbs. This obviates
the necessity of any cal-
culation and the use of
the above formula.

The readings of the

chart have been found to

agree closely with the results obtained by calculation, for

average barometric readings, at elevations not exceeding

3,000 feet above sea-level.

Fig. 12a.

* Taylor Brothers, Rochester, N. Y., U. S. A.

CHAPTER IV
THE COMMON MINE GASES

86. The gases commonly found in mines are but few in
number; they have been enumerated in Table 1. All
mine gases are known to the miner by the general term
damps. The term has a Dutch or German origin
(Dampf, vapor, fumes) and means suffocating or noxious
gases. Later a distinction was made between the different
mine gases, which had previously been regarded as one,
and the terms chokedamp or hlackdamp, whitedamp, stink-
damp, firedamp, and afterdamp came into general use to
indicate the several gases now known as carbon dioxide,
carbon monoxide, hydrogen sulphide, and methane; after-
damp is still called by that name, it being the variable mix-
ture of gases resulting from a mine explosion. Among min-
ers and many mining men, the common mine gases are
better known by their old names, which, however, have
fallen into disuse in chemical and other technical books.
In Table 1 the several names of each gas are given, but in
these pages preference will be had for the first name given,
in each case, as being the proper chemical name and the
one by which the gas is now most widely known.

87. Methane, Light Carbureted Hydrogen, Marsh Gas. —
This is a colorless, odorless, and tasteless gas; symbol
CH4, specific gravity .559. It occurs as an occluded gas

100 MINE GASES AND EXPLOSIONS

in coal seams and contiguous strata, having been produced
in the metamorphism of the carbonaceous matter forming
the coal, when this action has taken place with the ex-
clusion of air and in presence of water„ It is one of the
earlier products of the distillation of petroleum. Being
lighter than air, its tendency is to accumulate at the
roof and in the higher or rise workings of the mine. The
gas is combustible, burning with a pale, blue, lambent
flame, such as is seen over a freshly fed anthracite fire;
the pure gas will not, however, support combustion, but
promptly extinguishes the flame of a safety lamp exposed
to a body of the gas unmixed with air. The pure gas will
not support life, but suffocates by excluding oxygen from
the lungs; it is not, however, a poisonous gas, but mixed
with air in sufficient quantity may be breathed for a long
time with impunity, producing no other effect than a
slight giddiness, which passes off on return to fresh air.
This gas is detected by observing the pale blue flame
cap that envelops and surmounts the flame of a safety
lamp when the gas is present in sufficient quantity.

88. Firedamp. — Methane diffuses rapidly into air, form-
ing when mixed with the air in certain proper tons a very
explosive mixture called by the miners firedamp. In
England and on the continent, any mixture of marsh gas
and air is called firedamp, but in this country a firedamp
mixture is generally understood to be explosive or at least
inflammable.

As previously stated, methane or marsh gas is com-
bustible, but when present in small quantities in the air
the dilution of the gas is so great as to prevent its ignition
as a body of gas. Such small percentages of gas in the
air are consumed in contact with flame or other source
of heat sufficient for the purpose, and the resulting com-

THE COMMON MINE GASES 101

bustion of the gas gives additional heat, which in turn
increases the volume of the flame. As the percentage of
the gas is increased the mixture becomes inflammable at
5.55 per cent., for pure methane (Table 12), the mixture
burning quietly. As the proportion of gas is further in-
creased the combustion is more rapid and the mixture first
becomes explosive at 7.14 per cent. The explosive violence
now increases with the percentage of gas in the air and
attains a maximum at 9.46 per cent. Beyond this point
as the percentage of gas is increased the explosive violence
decreases and ceases altogether when the percentage of gas
in the air is about 16.67 per cent., for pure methane. The
mixture of gas and air is still inflammable, however, and
remains so as the percentage of gas is further increased,
till there is sufficient gas present to render the mixture
extinctive of its own flame, which is the case when the
mixture contains 29.5 per cent, of pure methane (see also
Table 17).

The explosive limits of methane have been determined
for the pure gas by experiment in the laboratory, and are
given below (Table 12), together with the maximum ex-
plosive point of the mixture. A firedamp mixture attains
its maximum explosive force w^hen the proportion of the air
is just sufficient for the complete combustion of the gas,
which is determined by calculation, as shown below. The
proportions given will vary slightly from the results of
actual practice, according to the character of the gas
issuing from the strata, which is seldom if ever pure marsh
gas.

89. Feeder Gas. — Gas as it comes from the natural
strata is called feeder gas, and consists of a variable mix-
ture of hydrocarbon gases, chiefly marsh gas, olefiant gas,
and ethane, together with different proportions of carbon

102

MINE GASES AND EXPLOSIONS

dioxide, nitrogen, oxygen, and rarely traces of carbon
monoxide. Table 10 shows the amount and composition
of the gaseous mixtures evolved from numerous coals at
212° F., in a vacuum. These evolved gases are an index
of the possible and varied composition of feeder gas, in
different localities.

Table 10

amount and composition of gas evolved from different

coals at 212° f.

Gas from

Percentage of Evolved Gases

Locality of

100
Grams
of Coal,

Kemarks

Coal

Cu. In.

CH4

CO2

C2H6

South Wales

3.5

62.78

36.42

.80

Bituminous

< (

3.4

63*76

29.75

5.44

1.05

< (

( (

12.2

87.30

7.33

5.04

.33

S learn coal

i <

4.6

72.51

14.51

12.34

.64

Semi-bituminous

((

23.4

86.92

3.49

9.25

.34

Steam coal, hard

e I

34.7

93.13

4.25

2.62

Anthracite

Lancashire

26.3

80.69

8.12

6.44

Cannel

< <

21.9

77.19

5.96

9.05

' ' very hard

Westphaha

1.4

89.91

7.50

2.59

Gas coal (20° F.)

((

1.1

24.85

58.48

2.56

4.11

t( (I ((

While the most of the above analyses were made from
samples of coal obtained fresh from the mine, it must be
remembered that the hydrocarbon gases, marsh gas and
defiant gas, transpire and escape from the coal more
quickly than carbon dioxide, nitrogen, or oxygen, the
effect of which would be to reduce the percentage of the
former and increase that of the latter gases, so that, in
general, feeder gas coming from the strata would be richer
in hydrocarbon gases and poorer in carbon dioxide and
nitrogen than what is shown above. Following is a table
giving the analyses of the gases coming from a few mine
blowers and bore-holes.

THE COMMON MINE GASES

103

Table 11

COMPOSITION OF GASES TAKEN FROM
BORE HOLES

MINE BLOWERS AND

Locality

CH4

CO2

Remarks

Dunraven mine, South Wales
Garswood mine

96.70
88.86
99.10
79.16
90.00
87.16
77.69

2.79

8.90

.70

17.04

9.25

11.73

18.48

.47 .

.41 1

.20 .

.19

.15
1.11 .
3.77

60
06

Blower

Karwin mine, Austria

Hruschau mine, Austria

Peterswald mine, Austria. . . .
Segen Gottes mine, Germany.
Liebe Gottes mine, Germany

ft
((

Bore-hole

The above analyses are sufficient to show the wide varia-
tion in the composition of blower or feeder gas in different
locaHties and different coals. It is evident that it would
be unsafe to base precise expectations on any supposed
composition of feeder gas, as this is too variable.

90. Inflammable and Explosive Range, Methane. — The
inflammable and explosive limits of pure marsh gas should
be known, and the effect of each of the mine gases to widen
or narrow these Hmits should be carefully studied.

Table 12
inflammable and explosive limits and maximum explo-
SIVE POINT OF METHANE (mARSH GAS) , SHOWING PERCENT-
AGE OF GAS IN MIXTURE

Proportion of Gas to Air

Percentage
of Gas in
Firedamp
Mixture

Inflammable and Explosive Range

Gas
(Volumes)

Air
(Volumes)

Higher injElammable limit

Higher explosive limit

Maximum explosive point. . . .

Lower explosive limit

Lower inflammable limit

17.00

13.00

9.57

5.00

2.39

5.55

7.14

9.46

16.67

29.50

104 MINE GASES AND EXPLOSIONS

Table 12 gives both the inflammable and explosive limits
and the maximum explosive point of pure methane (marsh
gas), and the percentage of gas in each of these firedamp
mixtures.

91. Effect of other Gases on Firedamp. — The explosive
character of firedamp is greatly modified by the presence of
other gases, which widen the explosive range and increase
the explosive force if the gases themselves are explosive;
but if not the explosive range and force of the firedamp is
decreased.

(a) Olefiant gas renders firedamp more easy to ignite
and increases its explosive force. In mining parlance, it
makes the gas sharp, by which is meant the gas is fresh
from the strata, and more active, agitates the flame more
and obstructs the formation of the flame cap, which is
always difficult to observe in sharp gas. Fresh feeder
gas as it issues from the strata and before it is diluted
with the mine air is generally sharp. The effect of the
presence of olefiant gas is to sharpen firedamp and in-
crease the danger from this cause.

(h) Carbon monoxide greatly widens the explosive range
of firedamp, making mixtures of marsh gas and air that are
inexplosive, dangerously explosive. This gas when presen':
in firedamp invites the formation of the flame cap, and
increases its height as well as the height of the flame itself.
There is no trouble to obtain a good cap when carbon
monoxide is present, unless its effect is counteracted by
the presence of other gases. The gas intensifies the explo-
sion of firedamp, lengthening the flame of the explosion and
propagating the action.

(c) Carbon dioxide reduces the explosiveness of firedamp
in proportion to the amount present in the mixture. \\Tien
the firedamp is at its most explosive point, one -seventh of

THE COMMON MINE GASES 105

its volume of carbon dioxide added will render the mix-
ture inexplosive (Table 17).

(d) Nitrogen acts to dilute firedamp and weakens its
explosive force, but the gas is wholly inert and plays no
other part. When firedamp is at its most explosive point,
one-sixth of its volume of nitrogen added will render the
mixture inexplosive.

(e) Coal dust has the same effect on firedamp as carbon
monoxide, distilled from it by the flame of burning gases.

92. Carbon Monoxide, Carbonic Oxide. — This is a color-
less and odorless gas; symbol, CO, specific gravity .967;
it is the whitedamp of the miners. This gas is chiefly
formed in the mine by the slow combustion of carbonaceous
matter in the waste places or abandoned workings where
there is little or perhaps no circulation of air; it is one of
the chief products of gob and other mine fires, and is also
largely produced by the explosion of powder in blasting,
or the explosion of gas in mines, in a Hmited supply of air.
It is carbon monoxide that in burning produces such large
volumes of flame when black powder is used in blasting.
At times the gas is not all fired, but a portion collects in the
crevices and open space behind a standing shot. It is then
that the miner is often burned by the unexpected flash of
flame that bursts forth when he innocently puts his lamp
in behind the coal to examine the effect of the blast. Car-
bon monoxide is alsa formed in large quantities whenever
the flame of a blast or explosion of gas is projected into an
atmosphere filled with fine coal dust. The gas is distilled
from the dust by the heat of the flame. It occurs to a
very slight extent only, as an occluded gas in coal. Being
somewhat lighter than air, the gas has a tendency to col-
lect at the roof and higher workings, but this tendency is
so slight it is usually overcome by the movement of the air.

106 MINE GASES AND EXPLOSIONS

Carbon monoxide is combustible. It is not an extinctive
gas, as is shown by the fact that lamps burn more brightly
in the presence of this gas than in pure air.

Carbon monoxide is an extremely poisonous gas, being
quickly absorbed by the blood when breathed into the
lungs. It acts as a narcotic, producing drowsiness or
stupor, followed by acute pains in the head, back, and
limbs, and afterward by delirium and death if the victim
is not rescued. No exact percentage of this gas can be
stated as certainly producing fatal results under all con-
ditions, as this will depend not only on the physical con-
dition of the person and the length of time the poisonous
air is breathed, but to an equal extent on the proportion
of oxygen in the air. Under the conditions of mining
the depletion of the oxygen of the air to a dangerous
extent is not infrequent, and it is then that extremely
low percentages of carbon monoxide are fatal to life.
Dr. Haldane, who is probably the highest authority on
this subject, states that when the oxygen has been re-
duced to 10 per cent., the presence of .05 per cent, of
carbon monoxide will produce a fatal effect when breathed.
Ordinarily it is stated that the presence of ten times
this amount, or .5 per cent., of the gas may be considered
as fatal to life (Art. 117).

Carbon monoxide gas is ordinarily detected in the
mine by the increased brightness of the flame, which
also reaches upwards in a slim taper blaze, burning quietly.
Reliance should not, however, be placed on this test
as making known an unsafe condition of the air in
time to escape danger. The safest precaution to adopt
whenever it becomes necessary to enter a place where
the presence ^of this gas may be or is- suspected is to carry
along a live mouse in a small wire cage. Dr. Ilaldane

THE COMMON MINE GASES

107

states that so sensitive is this little animal to the effect of
the gas, that it will be rendered unconscious in about one-
twentieth of the time required to produce the same result
in a person, thus giving ample warning in time to with-
draw. Mine workings in which mice and rats thrive may be
assumed to be free from any dangerous amount of white-
damp, and thus these troublesome pests may prove a
blessing at times. Canary birds are often used in the
same manner to detect the presence of the gas.

Dr. Haldane suggests that the most delicate test for
carbon monoxide, and one by which as small a quantity
as .01 per cent, may be readily detected in the air, is the
hlood test. He argues that since this gas is absorbed by
and affects the blood organisms, especially the hemoglobin
or colored matter, it is to this the test should be apphed
to discover the presence of the gas. A few drops of defi-
brinated ox blood are first diluted 100 times with pure water,
or 3 large drops of blood drawn
by pricking the finger are added
to a fluid ounce of water, making
a buff-yellow solution. This solu-
tion is then equally divided be-
tween two test tubes (Fig. 13).
One of these is provided with a
long and a short glass tube passing
through the cork as shown. The
air to be tested is then siphoned
or drawn through this test tube,
entering the long tube at a and
bubbling up through the liquid and

passing out at h. If the air contains but .01 per cent, of
carbon monoxide, the gas will impart a pink hue to the
hquid, which can be best seen by comparing the Hquids

Fig. 13. — Ihe Blood Test
for Carbon Monoxide

108 MINE GASES AND EXPLOSIONS

in the two test tubes held side by side before a white
sheet of paper.

When mixed with air in certain proportions carbon
monoxide is explosive. The gas has the widest explosive
range of 8.ny of the mine gases except hydrogen. The
lower explosive limit, 1 volume of gas to 13 volumes of air,
corresponds to the higher explosive limit of marsh gas.
The higher explosive limit of the gas is reached when the
mixture contains 1 volume of gas to 75 volumes of air
(Art. 115, Table 15).

93. Poisonous Action and Effect of Carbon Monoxide.
Such are the deadly effects of this gas in mining, that it
is of the utmost importance to obtain the best information
at hand in regard to its action and poisonous effect on
the system, the symptoms of such poisoning and the most
effective remedies. When air containing the smallest
quantity of the gas is breathed into the lungs, the gas
is rapidly absorbed by the hemoglobin or colored substance
in the corpuscles of the blood to the exclusion of the
necessary oxygen. Such is the affinity of these particles
for the gas that they retain it with great vigor and part
with what they have absorbed, with difficulty and very
slowly. The poisonous effect is therefore cumulative,
greatly increasing the danger of the continued breathing
of air containing even the smallest percentage of the gas.
Recovery from the effects of poisoning by this gas is slow.
The symptoms of poisoning by carbon monoxide are pal-
pitation of the heart and a sudden weakness in the limbs,
accompanied with a sensation of giddiness just as the
victim lapses into unconsciousness. It is a peculiarity of
this poisoning that the victim loses his power to move
before he is well aware of his danger. The victim of this
gas sometimes becomes delirious and violent on being

THE COMMON MINE GASES 109

brought to fresh air. Poisoning by carbon monoxide gives
to the blood after death a bright-red color, which it still
retains on exposure to air.

The form of treatment first employed for cases of car-
bon monoxide poisoning was that suggested by Dr. J. W.
Thomas, who recommended the discontinuance of alco-
holic stimulants, substituting therefor the enforced inhala-
tion of oxygen, and inducing respiration by artificial means.
Later the use of peroxide of hydrogen or hydrogen dioxide
(H2O2) has been found most efficacious. The use of stim-
ulants is discountenanced. It is of great importance to
keep the patient warm by wrapping him in blankets.

94. Carbon Dioxide, Carbonic Acid Gas. — This also is a
colorless and odorless gas; symbol CO2; specific gravity
1.529; it is the hlackdamp or chokedamp of the miners.
This gas is, for the most part, the product of the complete
combustion of carbonaceous matter in a plentiful supply
of air. It is largely formed in mines by the breathing of
men and animals, the burning of lamps, explosion of
powder, etc. It also exists in variable quantities, as an
occluded gas in coal seams and the contiguous strata, and
is evaporated to a limited extent from mine waters hold-
ing it in solution. Being heavier than air, its tendency is
to accumulate at the floor and in the lower or dip workings
of the mine. This gas is not combustible and does not
support combustion; a small quantity present in the air
dims the flame of the lamp, which is completely extin-
guished when larger quantities of the gas are present.
Carbon dioxide does not support life, but suffocates by
excluding oxygen from the lungs. It is not generally con-
sidered as a poisonous gas, although it produces a marked
effect on the system when breathed in sufficient quantities
or for a sufficient length of time. It has been suggested

110 MINE GASES AND EXPLOSIONS

these effects are not satisfactorily explained, except on the
basis that the gas exerts a poisonous effect on the organ-
isms of animal life, but as yet such poisonous effect has
not been proven. The percentage of carbon dioxide
necessary to extinguish a flame or to produce a fatal effect
when breathed depends on the percentage of oxygen in the
atmosphere in question, as will be shown later (Arts. 116
and 118).

Blackdamp is not nearly as dangerous in mines as
either whitedamp or firedamp, because of the timely warn-
ing given of its presence by the dim burning of the lamps.
Ordinarily an atmosphere becomes extinctive before it is
irrespirable, except when poisonous gases are present;
that is to say, an atmosphere in which a lamp is extinguished
is usually respirable, provided no poisonous gases are
present. It is, however, not only necessary, as a general
rule, but prudent to withdraw promptly from an atmos-
phere in which lamps refuse to burn. The effect of carbon
dioxide on the flame of a lamp serves as the best means
for its detection. Reference has already been made
(Art. 91) to the effect of this gas on firedamp. The victim
of the gas should be removed to fresh air, and alternate
cold and lukewarm applications made to the chest, while
the limbs and body are rubbed briskly to induce circula-
tion and efforts made to induce artificial respiration.
When consciousness is restored the patient should be put
to bed and kept quiet for several days and carefully watched
to avoid a relapse.

95. Hydrogen Sulphide, Sulphureted Hydrogen. — This
is a colorless gas, having a strong odor resembling that of
rotten eggs, which gave it originally the name of stink-
damp among the miners. Its symbol is H2S, and its
specific gravity 1.1912. This gas is formed in the mine by

THE COMMON MINE GASES 111

the decomposition of iron pyrites or bisulphide of iron
(FeS2) in presence of moisture, the hydrogen of the water
combining with the sulphur of the pyrites to form sul-
phureted hydrogen, while the iron is oxidized by uniting
with the oxygen. It occurs, with rare exceptions, in such
small quantities that it is readily carried away by the
most feeble air-current and forms no accumulations in
the mine; but otherwise, owing to its density, it would
be found at the floor and in the lower workings of the
mine. In volcanic regions it is possible to meet with
larger quantities of this gas, as it is a product of volcanic
action, sometimes forming a fourth of the volume of the
gases emanating from such eruptions. The gas is readily
soluble in water, which absorbs about three times its
volume. It is combustible, burning with a blue flame
like that of sulphur, and producing sulphur dioxide or
sulphurous acid (SO2) and water (H2O). The gas un-
mixed with air does not support combustion or life.
When mixed with 7 times its volume of air it forms a
violently explosive mixture. The gas is extremely poison-
ous, acting to derange the system when breathed in small
quantities, and producing prostration and unconscious-
ness when inhaled in larger quantities in the air. Its
offensive smell furnishes the best means for its detection.
The victim should be removed to fresh air, the body
and limbs rubbed briskly and kept warm. Stimulants
may be administered.

96. Olefiant Gas, Ethylene, Ethene. — This is one of the
heavy hydrocarbon gases, which, associated with methane
or marsh gas (CH4) and other gases, occurs to a vary-
ing but hmited extent as an occluded gas in coal seams.
The symbol of olefiant gas is C2H4, and its specific gravity
.978; it is a product of the formation of coal in the absence

112 MINE GASES AXD EXPLOSIONS

of water. It is a colorless gas, having a sweetish taste
and a sUght odor resembUng ether or garlic, that often
alone betrays its presence to the experienced miner. It
does not occur separately in sufficient quantities to form
any dangerous accumulations in the mine, but is asso-
ciated with marsh gas, and exerts a marked influence
on the character of the firedamp as explained (Art. 91).
The gas is combustible, but does not support combustion
or life. It burns with a much brighter flame than that
of marsh gas and not as quietly, the flame of the safety
lamp being more disturbed when this gas is present in
any considerable quantity. The action of the flame
in this respect, together with the faint odor of the gas,
furnishes the best means for its detection in the mine-.

Another of the heavy hydrocarbon gases that occurs
as an occluded gas associated with methane is ethane
(C2H6), specific gravity 1.0366. Like methane this gas
is a product of the distillation of petroleum. Its proper-
ties are similar to those of marsh gas except it is nearly
twice as heavy as that gas. It is a colorless, odorless,
and tasteless gas, and when mixed with air in certain
proportions is explosive. Methane and ethane are the two
most important members of the marsh gas series, while
olefiant gas or ethene is the most important of the olefines^

97. Nitrous Oxide. — This gas is often called laughing gas,
because of the pecuUar exhilarating effect it produces on
the system when inhaled. Its consideration is important
here since nitrous oxide often forms one of the constituent
gases of the afterdamp of an explosion of gas in a mine.
The symbol of nitrous oxide is N2O, and its specific gravity
1.525; it is a colorless and odorless gas, but has a dis-
tinctly sweet taste. The gas is almost as active as oxygen
in accelerating and supporting combuGijon; a spark or

THE COMMON MINE GASES 113

glowing ember of wood is at once kindled into flame in
this gas. The burning of CO to CO2 in this gas produces
40,400 more heat units per pound than when the same
combustion takes place in oxygen. This fact reveals the
possible enormous heat energy of the gas. The gas when
breathed in small quantities produces unconsciousness,
which is but of short duration and passes off quickly; it is
not poisonous. Treat by making effort to induce artificial
respiration, together with the use of a galvanic battery.

98. Nitrogen. — The great source of this gas is the
atmosphere, where it serves to dilute the oxygen and make
it fit to breathe. The gas also exists to a very large extent
in some coals as an occluded gas. It has been found to
form over 90 per cent, of the occluded gases in some
instances. As previously stated, this gas forms practically
80 per cent, or 4/5 of the volume of the air we breathe.
The various forms of combustion that take place in the
mine consume the oxygen and leave large volumes of nitro-
gen in the return current. The diminution of the oxygen
in this manner increases the poisonous effects of other
gases on the system, making smaller percentages of those
gases fatal to life than is the case in pure air. Nitrogen is
a colorless, odorless, and tasteless gas; its symbol is N
and its specific gravity .9713; the gas is not combustible
and does not support combustion or life. Like carbon
dioxide it dims and finally extinguishes flame when present
in sufficient quantity. Though often present in large
quantities, nitrogen does not tend to accumulate in the
mine as a separate gas, but its tendency is to diffuse and
again mix with the oxygen of the air in the proper propor-
tion as soon as it reaches the outer atmosphere. The gas
is wholly inert and has no poisonous effect; it plays no
part in any chemical reaction except as a diluent.

114 MINE GASES AND EXPLOSIONS

99. Oxygen. — This is a colorless, odorless, and tasteless
gas; symbol 0, specific gravity 1.1056; it is the great
supporter of life and combustion. Its chief source is the
atmosphere, of which it forms practically one-fifth part
by volume. It occurs as an occluded gas in very small
quantities in some coals.

100. Hydrogen. — This is a colorless, odorless, and taste-
less gas; symbol H and specific gravity .06926. Free
hydrogen is of rare occurrence in mines, but is found in
considerable quantities in the afterdamp of some explosions
of firedamp, when the marsh gas of the firedamp mixture
is in excess of that required to produce the maximum
explosive force, or exceeds 9.46 per cent. (Table 12). It
is not uncommon for miners to call marsh gas (light
carbureted hydrogen) by the simple name of hydrogen,
but this is of course a confusion of names that should be
avoided.

THE BEHAVIOR OF MINE GASES

loi. The laws that govern the motions of gases and
affect their behavior in the mine are those relating to their
gravity, density, occlusion, transpiration (effusion), and
diffusion.

102. Gravity of Gases.— The weight of gases increases and
decreases with the density of the gas and the force of gravi-
tation, the combined effect being perhaps better described
as the gravity of the gas. The downward or upward ten-
dency of a gas is determined by its gravity with respect to
the gravity of the air or other gases about it and forming
its atmosphere. The heavier or lighter gas by reason of
its relative gravity tends to settle lower or rise higher than
the air or gases forming its atmosphere. This tendency
of gases is in obedience to the law of gravitation, but its
practical effect is to cause the heavier mine gases to tend

THE BEHAVIOR OF MINE GASES 115

to accumulate in the lower or dip workings, while the
lighter gases possess a similar tendency to accumulate
in the higher or rise workings of the mine.

The temperature of a gas is important as determining its
density. A gas having a greater specific gravity than
another gas may still be lighter than that gas by reason of
its higher temperature. The relative temperature of the
air and a body of gas often determines the position of
the gas in mine workings, without apparent regard to its
specific gravity.

The accumulation of a body of gas either in a cavity or
lodging place in the roof, or in a low place or depression
in the floor will depend on the gravity of the gas with re-
spect to the position of the point where it issues from the
strata. The conditions most favorable to the accumula-
tion of gas occur when a light gas issues from the roof
strata or a heavy gas issues from the floor; because in
either case the gas tends to remain where it issues from
the strata. On the other hand, when a heavy gas issues
from the roof, or a light gas from the floor, the gravity of
the gas will cause it to fall in the first case and rise in the
second case, which brings the gas into contact with the
air by which it is carried away. In any case, the accumu-
lation of gas at any point in the workings of a mine will
depend on whether it issues from the strata faster than
the air-current takes it away.

The stratification of gas is frequent, both in standing gas
and in air-currents containing gas. It is a matter of
common experience that gas travels more or less in veins
or streams, which are the result of the incomplete mixing
of the gas and air. In making some laboratory tests it is
often difficult to get and maintain a uniform mixture of
the gas and air on this account.

116 MINE GASES AND EXPLOSIONS

The removal of a body of firedamp or other accumulated
gases from mine workings properly belongs to the subject
of Mine Ventilation.

103. Occlusion of Gases. — In the formation of coal the
metamorphism of the carbonaceous matter was accom-
panied by the evolution of gases that varied according to
the conditions coincident with the formation. It often
happened that owing to the impervious character of the
deposits overlying the coal these gases could not escape,
but were imprisoned in the strata, being confined either
in the coal itself or forced into and impregnating the strata
overlying or underlying the coal. Large quantities of
hydrocarbon gases, nitrogen and carbon dioxide and cer-
tain liquid bituminous matters, together with small
amounts of oxygen and traces of carbon monoxide were
thus entrapped in the measures. These gases are said
to be occluded (hidden) in the coal and contiguous strata.
It is estimated by eminent authorities on mine gases that
certain coals hold, chemically, bituminous matter capable
of producing from 10,000 to 12,000 cubic feet of gas
per ton of coal, beside occluded gases, which are held
mechanically under a compression of 200 atmospheres
and which would equal 5,000 cubic feet of gas per ton
of coal, if measured at the ordinary temperature and
pressure. The pressure of the confined gases has in
many cases been found to be equal to 500 and 600
pounds per square inch. That the actual pressure of
occluded gases is much less than the estimated pressure
due to their volume is perhaps owing to the absorptive
power of the coal by which they are held. So great is this
pressure, however, that the gas fiUing the pores of the
coal in some instances sphnters and bursts the coal from
the working face of a breast, throwing it with great force

THE BEHAVIOR OF MINE GASES 117

in the face of the miner. The escape of the gas from the
face of the coal in a gassy seam generally makes a pecu-
liar hissing sound known to the miner as the singing of the
coal. The escape of the gas is not usually uniform over
the entire face of the coal, but occurs in spots or seams
affording easier effusion. In the working of a very gassy
seam the extraction of the coal sets up a movement in the
overlying strata that is quite generally accompanied with
audible sounds produced by the working of the gas be-
tween the foliations of the strata. The movement of the
gas is always toward the opening in the seam, and this
movement is the probable cause of the dull, heavy con-
cussions of the strata, which the miners call poundings,
knocking s, humps, etc.

104. Transpiration or Emission of Mine Gases. — The
gases occluded in coal seams and the contiguous strata
escape gradually and more or less continuously from the
pores of the strata, where the latter are exposed by the
operations of mining. This process is called transpiration
or effusion, and continues till all the gas in proximity to
the exposed faces of the coal has drained away and es-
caped. The transpiration of gas is always greater in new
workings where fresh faces of coal are being exposed
daily, provided the supply of gas is not inexhaustible.
It frequently happens, however, that owing to heavy
roof falls in the abandoned mine workings these workings
still continue to furnish large quantities of gas after long
periods of time, and often prove a serious menace to the
safety of the men and the security of the mine. This is a
common occurrence in mines where the gas is found in the
roof or overlying strata. Owing to causes that are for
the most part hidden, the transpiration of gas in a mine
will sometimes cease quite suddenly, and for a long period

118 MINE GASES AND EXPLOSIONS

thereafter the mme will be free from any appreciable
amount of gas, very much as an active volcano will be-
come extinct. Again, gas will often appear in a mine
previously free from gas. A change in the gaseous con-
dition of a mine may generally be expected when ap-
proaching a fault, and the experienced miner will then
use extra precaution. It is proverbial that gas follows a
fault, and this is true because it is generally the line of
least resistance. While a fault usually acts as a channel
by which the gas escapes from that portion of the seam,
it sometimes happens that gas is conducted thereby to the
seam being worked, from other strata more gaseous than
the seam itself. It is frequently the case that the miner
loses the gas after passing through a fault, and as often
perhaps fresh gas is found on the other side of the fault;
so that the rule is very general that the near approach to
a fault forebodes a change in the gaseous condition of
the mine, and due precautions should therefore be taken.
105. Rate of Transpiration. — The laws that govern the
transpiration of gases may be briefly stated as follows:

1 . For the same gas or air, the rate of transpiration varies
with the pressure of the gas; in other words, the volumes of
the same gas that transpire in equxxl times are proportional
to the pressure of the gas.

2. For the same gas or air, the rate of transpiration de-
creases as the temperature of the gas increases, hut not in
the same proportion.

3. For the same gas or air, the rate of transpiration through
tubes or pores of equal diameter is inversely as the length of
the tube.

4. The rate of transpiration is independent of the material
of the tube or pores through which the gas passes.

5. The rate of transpiration is different for different gases.

TBE BEHAVIOR OF MINE GASES HO

The following table gives the relative velocities of trans-
piration of the important mine gases, referred to air as
unity :

Table 13
rates of transpiration of mine gases, air=1

Gas

Hydrogen

Olefiant gas

Methane

Sulphureted hydrogen. .

Carbon dioxide ,

Carbon monoxide ,

Nitrogen ,

Air

Oxygen

Relative Velocity
of Transpiration

2.066
1.788
1.639
1.458
1.237
1.034
1.030
1.000
.903

Since the different gases have different rates of transpira-
tion, the composition of the gaseous mixtures occluded in
the strata is quite different from that which issues there-
from. In other words, the composition of feeder gas is
always materially changed during its transpiration. As
observed in the above table, the hydrocarbon gases, olefi-
ant gas and methane, have a much higher rate of tran-
spiration than the extinctive gases, carbon dioxide and
nitrogen. Thus, 1,788 volumes of olefiant gas or 1,639
volumes of methane will transpire in the same time that
is required for 1,237 volumes of carbon dioxide or 1,030
volumes of nitrogen. In a general way this fact is illus-
trated by comparing the occluded gases of different coals
(Table 10) with the feeder gases that have transpired and
filled pockets, cavities, or bore holes (Table 11). The
former are rich in carbon dioxide and nitrogen, while
the latter are richer in methane or marsh gas. The same-
cause also makes the first transpirations in a newly

120 MINE GASES AND EXPLOSIONS

opened district, or the gas of virgin coal richer in hydro-
carbon gases, while the emissions from older workings
often contain more carbon dioxide and nitrogen and less
hydrocarbon gases.

io6. Gas Pockets, Feeders, Blowers. — A pocket of gas is
formed whenever the gases occurring in the strata find their
way into and fill a cavity or void in the rocks. This is not
an infrequent occurrence. A reservoir of gas is thus formed

Fig. 14. — Showing Face of Chamber and Gas Working in Roof
and Coal

of greater or less proportions, depending only on the size
of the cavity and the supply and pressure of the confined
gas. Gas pockets and gas in general are of more frequent
occurrence along the axis of a broad anticline; but where
the strata are much disturbed and broken the gas has
generally drained away. A pocket of gas is illustrated in
Fig. 14 as overlying the roof shale. The extraction of
the coal in the chambers of the seam below has resulted
in breaking the roof strata and ere vicing the coal. The
action has been greatly assisted by the enormous pressure
of the gas acting on the unsupported roof. A gas feeder
is any stream of gas issuing from a crack or crevice in the
seam or in the roof or floor. A blower is formed when

THE BEHAVIOR OF MINE GASES 121

the gas of a feeder issues under a strong pressure. The
gas contained in coal greatly assists the work of mining
and cutting the coal, as it makes it more brittle and
susceptible to the pick.

107. Outbursts of Gas. — An outburst of gas refers to
any sudden emission of gas in large quantities from the
strata; the gas may or may not be explosive. Instances
are recorded of large outbursts of carbon dioxide in mines
in France, where the miners were compelled to flee for
their lives. Violent outbursts of marsh gas and nitrogen
are of common occurrence, where the chambers and mine
passages are often completely filled with hundreds of tons
of broken coal and rock. The immediate cause of these
occurrences is the weakening of the strata by the extrac-
tion of the coal. As illustrated in Fig. 14, the pressure
of the gas frequently becomes distributed over a large
area of the roof strata or the rib coal, and the roof or the
coal being too weak to withstand this pressure is thrown
down with great force. Gas in the roof often makes the
latter heavy and should be drained by bore holes put up
in the roof at intervals along the headings and chambers.
Heavy outbursts of gas- are generally preceded by the
poundings or bumps previously described. These warn-
ing sounds are well known to the miner, who does not fail
to heed them and stay out till the danger is passed. These
poundings sometimes continue for several days before the
outburst of gas occurs.

108. Diffusion of Gases. — When two gases, or a gas and
air that do not act on each other chemically, are in con-
tact with each other, a diffusive action at once begins
between their molecules at the point of contact. Assum-
ing that the molecules of all matter are in a state of constant
motion, vibrating through a distance determined by the

122 MINE GASES AND EXPLOSIONS

nature and density of the matter, it is evident there can
only be a true balance and a state of equilibrium, where
the matter is homogeneous in a sense that its molecules are
possessed of equal kinetic energy. Any other condition
prevailing at any point leaves the molecular vibrations
unsupported, and the result is a procession of the mole-
cules. The molecules of one gas are thus made to intrude
among the molecules of another gas at a fixed rate of pro-
gression, causing an intimate mingling of the molecules
of the two gases and the mixing of the gases in fixed pro-
portions. This phenomenon is called diffusion, and is very
different in its results from the accidental and ununiform
mixing of gases that occurs from various causes. Diffu-
sion produces a gaseous mixture of definite proportions,
just as chemical reaction produces chemical compounds of
fixed proportions.

Diffusion takes place in larger quantities in a moving
current than in still air, not because the diffusion itself^
is more rapid, but the motion of the air constantly changes
the surfaces of contact, bringing fresh air and gas together,
which promotes the diffusion. For the same reason a
light gas coming from the floor and having a tendency to
rise, or a heavy gas coming from the roof and having a
tendency to fall, will diffuse into the air more readily,
owing to its position in the airway. A feeder of marsh gas
in the floor is thus less liable to cause an accumulation of
gas than one in the roof, because the former is largely
diffused and carried away by the current, even though little
air may be passing, while the latter diffuses slowly into the
current, being undisturbed by gravity, and there being
no force save that of the current itself to alter its surface
of contact with the air. The same is likewise true with
respect to carbon dioxide, which presents a far less ten-

THE BEHAVIOR OF MINE GASES 123

dency to accumulate when coming from the roof than when
the feeder is in the floor.

Such are the physical conditions in mines that gases do
not travel any great distance, except as they are borne on
the air-current that circulates through the mine. Conse-
quently, mine gases are found in largest proportion where
they are generated or issue from the strata. The only
exceptions to this rule are marsh gas in a weak air-current
and carbon dioxide or blackdamp, which is often difficult
to convey away, but exhibits a tendency to settle gradually
to the lower parts of the mine. Blackdamp often requires
a strong air-current for its removal, on this account. The
results of diffusion are therefore largely confined to a com-
paratively small area where the gases are formed. Where
marsh gas is found accumulated in distant rise workings,
very little, if any, of the gas can be assumed to have trav-
eled hither in the air-current; it has either found its way
through the joints of the strata, or has issued on the spot
as feeder gas, unless the air-current passing through the
mine is weak. All the mine gases, with the possible ex-
ception of blackdamp (CO2), when once absorbed by the
air-current are carried by it out of the mine, and very
little if any escapes to accumulate at other points.

109. Rate of Diffusion. — The laws that govern the dif-
fusion of gases into each other and into air are quite differ-
ent with respect to the rate or relative velocity of the gases
from those relating to transpiration. The rate of tran-
spiration (Table 13) has no relation to the density of the
gas, except as the density is increased or decreased by
the pressure under which the gases are occluded and
which affects the rate of the transpiration of the gas
(Art. 105). On the other hand, the rate of diffusion of
each gas has been found by careful experiment to vary

124

MINE GASES AND EXPLOSIONS

inversely as the square root of the density of the gas. Of
course the pressure affects the densities of all the gases
alike, and does not therefore alter their relative velocities
or rates of diffusion. In Table 14, the several mine gases
are given in the order of their relative velocities, beginning
with the highest.

Table 14

rates of diffusion of mine gases, air=1

Gas

Hydrogen

Methane (marsh gas),
Carbon monoxide. . . .

Nitrogen

Olefiant gas

Air

Oxygen

Hydrogen sulphide. .
Carbon dioxide

Specific
Gravity

.0693

.5590

.9670

.9713

.9780

1.0000

1 . 1056

1.1912

1 . 5290

VSp. Gi

3.7987

1.3375

1.0169

1.0147

1.0112

1.0000

.9510

.9163

.8087

Relative
Velocity of
Diffusion

3 . 8300

1 . 3440

1.0149

1.0143

1.0191

1 0000

.9487

. 9500

.8120

The values given for the relative velocities of diffusion
in the last column are those determined by experiment;
it will be observed these correspond closely with the cal-
culated value of the reciprocal of the square root of the
specific gravity of the gas in each case. In comparing
this table with Table 13, it is interesting to note that
both olefiant gas and sulphureted hydrogen, having com-
paratively high rates of transpiration and, as a conse-
quence, transpiring freely when present in the coal, have
lower rates of diffusion. Each of these gases when pres-
ent in firedamp lower the point of ignition of the mix-
ture. It is well they are not found in larger percentages
among the occluded gases of coal seams.

The rate of diffusion of the mine gases has an important

THE BEHAVIOR OF MINE GASES 125

bearing on the composition and therefore the character
of gaseous mixtures. While it is a fact that bodies of gas
are mixed mechanically by the circulation of the air and
other disturbing causes in the mine, yet this mixing is not
uniform and does not produce the intimate mixture that
is the result of diffusion. In any case diffusion is still at
work in all gaseous mixtures to produce the uniform
intimate mingling of the gases in the proportions deter-
mined by their rates of diffusion. It must not be thought
for a moment, however, that ultimately all mixtures of
gases in mines will be in the proportions indicated by their
rates of diffusion. This is the tendency of mixtures, but
owing to the many disturbing influences constantly at
work these proportions are only realized under certain
conditions. For example, it is observed from Table 14
that 1,344 volumes of marsh gas diffuse in the same
time as 1,000 volumes of air. If diffusion acted alone
in this case, the resulting mixture would contain 1,344
volumes of gas to 1,000 volumes of air, or 1 volume of
gas to .744 volume of air. But since the lowest inflam-
mable limit of marsh gas (Table 12) is 1 volume of gas
to 2.39 volumes of air, this mixture does not contain
sufficient air to render it either inflammable or explosive.
In the mine, marsh gas transpiring from a face of coal
meets with a large excess of air, and the motion of the
air or that of the gas, or both, combined with other dis-
turbing causes, often produces dangerous mixtures.

It is important that the volume of air in circulation be
sufficient for the proper dilution of the gases generated,
so that the mixtures formed will be neither explosive nor
inflammable.

126 MINE GASES AND EXPLOSIONS

MIXTURES OF GASES AND AIR

no. It is the nature of gases to intermingle and mix
freely with each other, either by diffusion in accordance
with its laws, forming mixtures of definite and fixed pro-
portions, or mechanically without uniformity and in no
fixed proportion, or more frequently by both of these
methods combined. In all of these there is no chemical
change or reaction, but each gas retains its own identity
and properties, and the properties of the gaseous mixture
are the result of the combined properties of the several
gases. The atmosphere is an example of a constantly
uniform mixture of oxygen and nitrogen. By what means
the constant proportion of these gases is maintained in the
atmosphere is not known, but it is a remarkable fact that
the immense consumption of oxygen, daily and hourly,
makes an almost inappreciable difference between the
composition of the atmosphere in a crowded city, as London
or New York, and that of the open field. That the pro-
found depth of the atmosphere forms an inexhaustible
supply is the only explanation to be offered for the phe-
nomenon. Firedamp, which is one of the most important
of the gaseous mixtures formed in the mine, has already
been explained in connection with marsh gas, it being
simply a dilution of this gas with air, in explosive propor-
tions (Art. 88). Many of the mixtures of gases, owing
to their behavior or properties, are frequently mistaken
by the miner for some new gas.

III. Flashdamp. — This is a common mixture of marsh
gas and carbon dioxide that presents the peculiar properties
of extinguishing the flame of a lamp held at the roof. After
a careful investigation of the behavior of this mixture in
the mine, the author has suggested for it the name of flash^

MIXTURES OF GASES AND AIR 127

damp, because the flame cap afforded by the marsh gas in
the mixture appears only as a momentary flash when the
lamp is first raised into the mixture and then promptly
disappears. The carbon dioxide present in the mixture
destroys the flame cap that the marsh gas would give, but
this does not occur till after the fresh air in the lamp has
been exhausted. If the air lower in the airway is suffi-
ciently fresh, the lamp when raised quickly into the gas
contains, for a moment only, a fresh atmosphere that
dilutes the gaseous mixture entering the lamp, and a dis-
tinct cap flashes up on the flame and as quickly disappears.
The conditions favoring the production of flashdamp
are where carbon dioxide is given off from the roof of a
seam generating marsh gas, or marsh gas is given off at
the floor of workings full of blackdamp. In either case
the conditions must be such as not to prevent the accumu-
lation of the mixture of these gases. The formation of
flashdamp is not probable where either gas becomes largely
diluted with air before they diffuse into each other. The
theoretical composition of flashdamp is 812 volumes of
carbon dioxide and 1,344 volumes of marsh gas or methane,
these being the relative velocities of diffusion (Table 14);
or the ratio is 1:1 .655, or, expressed as percentage, 37.66
per cent, and 62.34 per cent, of the two gases respec-
tively. The mixture is lighter than air, having a density
of .924, and it therefore has a tendency to collect at the
roof. It dims the flame of a safety lamp, which is com-
pletely extinguished in pure flashdamp and sometimes
even in more dilute mixtures. Flashdamp is a more dan-
gerous mixture than firedamp : first, because it is difficult
of detection and often escapes the notice of the fire boss,
who mistakes it for blackdamp, and has various ways of
accounting for its position at the roof; second, because

128 MINE GASES AND EXPLOSIONS

of the popular fallacy that this mixture, which extin-
guishes the flame of a lamp, is not explosive, whereas at
certain stages of dilution it becomes highly explosive.
Calculations Pertaining to Flashdamp. —

(a) Percentage composition :

Carbon dioxide (CO2) 812 volumes

Methane, marsh gas (CH4) 1,344 "

Flashdamp 2,156 "

812
Carbon dioxide 2156^^^^^^''-^^/^

Methane 2156'^-^^^ =62.34%

(b) Specific gravity:

Relative weight carbon dioxide. . 812(1 .529) =1,241 .548
" methane 1,344( .559) = 751.296

" flashdamp 1,992.844

The weight of 2,156 volumes of flashdamp is therefore
1,992.844 times the weight of one volume of air at the
same temperature and pressure, and its specific gravity
referred to air is therefore

1,992.844 -2,156 = .924.
(c) Explosive condition:

812 volumes
,344

^, - , ( carbon dioxide . ^

i lashdamp i ^^

^ ( methane 1,*

If the flashdamp be diluted with air suflacient to bring the
marsh gas to its most explosive point, the volume of the
firedamp will be 1,344 -f- .0946 =14,207 volumes; and the
carbon dioxide required to render this mixture inexplosive

MIXTURES OF GASES AND AIR 129

is 1/7(14,207) -2,029 volumes. It will be observed that
the undiluted flashdamp contains only 812 volumes of
carbon dioxide, and the mixture is therefore made highly
explosive by the addition of air.

Conditions often occur in the mine workings where the
proportion of blackdamp (carbon dioxide) in the flash-
damp is so large that the mixture is heavier than air and
tends to collect at the floor or other low places in the mine.
This may be called heavy flashdamp, while the accumu-
lation at the roof may be called light flashdamp. Heavy
flashdamp is even more difficult to detect than light flash-
damp, because of the increased dimming effect of the
blackdamp, but it is not as readily ignitable or as dan-
gerous.

112. Afterdamp. — This term describes any mixture of
the gaseous products of an explosion of gas in a mine.
The products of an explosion are always variable, de-
pending on the composition of the explosive mixture and
the conditions that affect the pressure and temperature of
the explosion. The composition of afterdamp is there-
fore variable and its character changes accordingly, and
may be said to be never twice alike. In a general way,
afterdamp may be described as consisting of a variable
mixture of gases, chiefly carbon dioxide, carbon monoxide,
nitrogen, and water vapor, beside smaller amounts of
nitrous oxide gas, and occasionally some unburned marsh
gas or free hydrogen.

Numerous tests have shown that when marsh gas is
burned in air all of the marsh gas is broken up into carbon
and hydrogen if the oxygen present is not less than one-half
the volume of the marsh gas (gas :air =1:2.39); and with
this proportion the carbon takes all of the oxygen, forming
carbon monoxide only, and the hydrogen -remains free, no

130 MINE GASES AND EXPLOSIONS

water vapor being formed, as expressed by tlie equation

2CH4+02+4N2=2CO + 4H2+4N2. . . (28)

From this point, as the proportion of oxygen or air is
increased, a small at first but ever increasing percentage
of carbon dioxide is formed, and likewise a small at first
but always increasmg percentage of hydrogen is converted
into water vapor. The increase of carbon dioxide and de-
crease of carbon monoxide, as the proportion of air to gas
is increased, is shown by the following results (Thomas) :

Gas to Air
1 : 4.5, 10% carbon forms CO2 and 90% carbon forms CO;
1 : 5.0, 13% " " '' '' 87% '' " ''

1 : 6.0,20% " " " " 80% " " "

1 : 9.57, all the carbon is converted into CO2.

The point of complete combustion is reached when the pro-
portion of gas to air is 1:9.57 (Table 12), when all of the
carbon of the marsh gas is burned to carbon dioxide, and
all the hydrogen is converted into water vapor, as has
been expressed by equation 7 (Art. 42).

Equation 28 above expresses the reaction that takes
place when the volume of the marsh gas is double that of
the oxygen in the air. Since oxygen forms 20.9 per cent,
of the air, the proportion of marsh gas to air would be
in this case 2(20.9) =41.8 to 100 volumes of air; or the
percentage of gas in the mixture would be

41.8

X 100 =29.47%.

100+41.8

Practically, then, when 29 per cent, of marsh gas is present
in mine air, or, say, nearly double the amount that marks
the lower explosive limit of the gas (Table 12), the burn-

MIXTURES OF GASES AND AIR 131

ing of this mixtare by reason of the explosion of a body
of firedamp elsewhere in the mine would produce a vol-
ume of carbon monoxide equal to the volume of marsh
gas burned, and double this volume of hydrogen and of
nitrogen. This shows some of the possibilities of the
gaseous composition of the afterdamp of a gas explosion.
Another important effect on the composition of the after-
damp is that produced by the incandescent carbon or
burning coal dust floating in the air. The burning carbon
floating in the atmosphere of the gaseous products of the
explosion reduces the carbon dioxide to carbon monoxide,
according to the equation

2C02+C2=4CO (29)

It will be observed that the most dangerous afterdamp
is formed by the explosion or burning, as the case may be,
of a mixture of marsh gas and air containing more than
9.46 per cent, of gas. It must be remembered that pre-
vious to an explosion there are in different parts of the
mine perhaps numerous bodies of gas, some of which are
explosive, containing between 7.14 per cent, and 16.67 per
cent., while others are only inflammable, containing more
or less than the above percentages of gas, while still others
contain so high a percentage of gas as to be not only not
inflammable themselves but extinctive of the flame of
the other gases, except as they may become diluted by
the blast of air caused by the concussion. It must also
be remembered that mixtures that are of themselves in-
flammable only, may be rendered explosive by reason of
the carbon monoxide produced about them by the burn-
ing of dust or otherwise. It is readily seen that owing to
such varying conditions and the powerful disturbances
of the air throughout the mine at the moment of the

132 MINE GASES AND EXPLOSIONS

explosion it would be presumption born of ignorance to
attempt to fix the composition of afterdamp except in
the most general way.

MINE AIR

113. It is natural to believe that when the air of a mine
is fresh it does not differ materially from atmospheric air.
This, however, is a mistake, since mine air at its best
differs in at least two important respects from the outside
atmosphere; namely, the depletion of the oxygen of the
air and the contamination of the air with the mine gases.
In the free outer air there are influences constantly at
work to restore the purity and original freshness of the
atmosphere that do not exist in the mine. One phase
of this revivifying work is shown by the fact that there
is actually less carbon dioxide present in the air near the
surface of the earth than higher in the atmosphere, owing,
probably, to the absorption of this gas by vegetation. The
normal amount of carbon dioxide in the atmosphere is
about 4 parts in 10,000 — .04 per cent. (Thomas) ; or .03
per cent. (Dr. Angus Smith). Mine air, on the other
hand, rarely contains less than .1 per cent., and frequent
analyses have shown it is not uncommon for the miner
to work all day in an atmosphere containing anywhere
from 2 to 5 per cent, of this gas.

It is quite commonly supposed also that methane (marsh
gas) is found in troublesome quantity only in coal mines;
but the recorded explosions in the Silver Islet mine, of
the Lake Superior region,* and the occurrence of the gas
in varying quantities in the stratified ironstone deposits
of Cleveland, the mineral veins of Colorado, the Chehsire

* Engineering and Mining Journal, Vol. 34, page 322.

MINE AIR 133

salt mines of England, the lead mines of Wales and Deroy-
shire, and in the salt mine at Bex, Switzerland, where jets
of the gas may be seen constantly burning, leave little
doubt but that methane, though commonly associated
with the coal measures, may occur in dangerous quantities
in any geological strata.

Sulphureted hydrogen gas occurs in largest quantity
in the Sicilian sulphur mines, where the mine water is
frequently saturated with the gas. Mercurial vapors con-
taminate the air of quicksilver mines. Besides gases,
floating particles of dust, the solid matters of lamp and
powder smoke, and organic matter produced by the ex-
halation of men and animals, and the decay of timber con-
taminate mine air very largely. A cheap quality of oil
burned in the lamps and the practice, which is far too com-
mon among miners working at the face, of adding much
petroleum (coal oil) to their sperm or lard oil do much to
foul the air in many mines.

The depletion of the oxygen in mine air, by the various
forms of combustion constantly going on and the breath-
ing of men and animals, is more hurtful than what is
often supposed. Dr. Angus Smith found, as the average
of over 300 analyses of mine air taken in different parts of
different mines, the following percentages of oxygen in
seemingly good air:

Sumps 20.14 per cent

Pillar drawings 20.18 "

Working faces 20.32 ''

Shaft bottoms (returns) , . . 20.42 ''

Intake air-currents (inby) 20.65 "

Large open areas 20.72 "

Free atmospheric air 20.90 *'

134 Mine Oas^s and explosions

Dr. Smith considers air as normally fresh when it contains
20.9 per cent of oxygen, impure when the oxygen falls
to 20.6, and very bad when it reaches 20.5 per cent.
However, the general ventilation of mines has very
greatly improved since Dr. Smith made his observa-
tions.

114. Gaseous Condition of Mine Air. — Upon the gaseous
condition of the air of a mine depends its character and
classification as being a non-gaseous, gaseous, or a fiery
mine. The gaseous condition of a mine is made known
by the proportion and character of the gases that may be
expected, in the natural order of events, to find their way
into the air circulating at the working face. It must be
accepted as a fact that mining operations will always en-
tail a certain reasonable risk with respect to gas. How-
ever, ignorance or disregard of the prevailing conditions
in any case causes heavy responsibilities to rest on the
management of the mine. A fiery seam is nothing less
than a fiery seam, and should be worked as a fiery seam,
and anything else is to assume an unconscionable risk on
the lives of men.

The old definition of a non-gaseous mine, as being a
mine in which gas does not exist "in quantity sufficient
to produce a visible cap on the flame of a common Davy
lamp," cannot be accepted as a safe definition today,
since Mr. William Galloway, the great exponent of the
Coal Dust Theory, has stated plainly that under certain
conditions common to many bituminous mines, the mine
air becomes highly explosive when it contains a percentage
of gas far too small to be seen on the lamp. A mine may
he classed as non-gaseous when it does not produce gas in
quantity sufficient to make accident therefrom possible, under
any conditions that may reasonably be expected to occur in

MINE AIR 135

the operation of the mine. The term non-gaseous should
convey the meaning that there is no possible risk, in this
respect, in the operation of the mine, and this meaning
should be duplicated in fact.

A gassy or gaseous mine is a mine generating gas in any
qiuxntity that makes accident therefrom possible, under any
conditions that may reasonably be expected to occur in the
operation of the mine. There are different degrees of the
gaseous condition, which make numerous well-known pre-
cautions necessary in the working of the coal.

A mine may be classed as a fiery mine when its gaseous
condition requires the constant use of safety lamps ex-
clusively throughout the mine. This condition requires
not only the rigid enforcement of strict regulations, but
the greatest watchfulness, thoroughness, and caution on
the part of every man employed in the mine.

The presence of gas makes itself manifest in two ways
as far as endangering the health or safety of the men or
the security of the mine is concerned, namely, by the
effect produced on flame and by the effect on the human
system. Fortunately, in almost every case occurring in
the mine the former effect precedes the latter. The
proposition must be studied by observing what takes
place when gas is present in the mine air. All the
effects destructive of life or property are produced
through the medium of the atmosphere. The atmosphere
of the mine furnishes the only support of the flame and
transmits the force of the blast that wrecks the workings;
the same atmosphere conveys to the system the poi-
sonous gases that are fatal to life.

The several mine gases that find their way into the
workings produce, according to the character and quantity
of gas present:

136 MINE GASES AND EXPLOSIONS

1. An explosive atmosphere or condition of the air;

2. An extinctive atmosphere capable of extinguishing
the flame of a candle or lamp, or that of burning gas;

3. A dangerous atmosphere affecting the respiration or
even producing insensibility, or lacking little of being ex-
plosive;

4. A fatal atmosphere, producing fatal results when
breathed but for a short time.

115. An Explosive Atmosphere. — What constitutes an
explosive atmosphere cannot be defined in a few brief
words. Careful experiment in the laboratory will make
known the explosive limits of a gas; that is to say, the
limiting proportions of gas and air between which the
mixture is explosive when pure gas is used. The results
of these experiments, while they are of great value in deter-
mining the relation of a gas to the phenomena of explo-
sion, can be accepted and applied to the interpretation of
what takes place in a mine only by way of suggestion.
Mine gases are not pure gases, but mixtures, in varying
proportions, of gases having often contrary properties.
Moreover, the explosive limits of a gas vary with its pres-
sure and temperature, and these are very uncertain ele-
ments in a mine. As a consequence, the explosive con-
dition of mine air is subject to much and often sudden
variation. An atmosphere that is safe under the ordinary
conditions of heat and flame to which it is subject is often
proved by sad experience to be highly explosive when
exposed to the flame of a blown-out shot, or when laden
with the fine dust incident to the cutting of the coal or
the operations of the mine. These facts must be borne
in mind when considering the safety of the mine air. Air
containing a percentage of gas far too small to be detected
by the lamp in the ordinary manner, and which is safe in

MINE AIR

137

the common meaning of that term, becomes highly ex-
plosive under the conditions that are caused by the acci-
dental explosion of a keg of powder, or a particularly
windy shot, or a blown-out shot, or a small dust explosion
in a chamber. Mr. Galloway found by experiment in a
mine shaft that an atmosphere containing fine coal dust
was explosive when it contained but .892 per cent, of
marsh gas. The following table gives the explosive range
of the inflammable mine gases:

Table 15
explosive range of mine gases

Gas

Hydrogen

Carbon monoxide. . . .

defiant gas

Methane (marsh gas)

Volume of Gas to Air

Lower Higher

Explosive Limit Explosive Limit

1:72
1:75
1:22
1:13

It is a fortunate circumstance that methane, the most
abundant of all the gases occluded in coal, has the least
explosive range of any of these gases; hydrogen has the
widest explosive range and carbon monoxide the next.
The explosive range of olefiant gas is even wider than that
of methane, and its presence in firedamp adds to the dan-
ger not only by making the mixture more readily ignitabie,
but by making mixtures explosive that would not other-
wise be explosive; that is to say, widening the explosive
range. Carbon monoxide, owing to its wide explosive
range and its frequent occurrence, being distilled from
coal dust by the flame of an explosion, is an element of
the greatest danger in mining.

138 MINE GASES AND EXPLOSIONS

There is some difference of opinion as to whether or not a
simple dust-laden atmosphere is explosive in the absence of
any gas whatever. Numerous experiments have been made
by eminent men to prove or disprove the theory, and it is
sometimes claimed that whenever an explosion of dust
has occurred it has been caused by a small percentage of
gas present in the air. Following an explosion of dust, in
the seeming absence of firedamp, in the Campagnac Colliery
(1874), M. Vital, an eminent French engineer, made some
experiments on fine coal dust and air, by which he found
the dust was explosive or at least inflammable in the
entire absence of firedamp. Mr. Henry Hall's experiments
first performed in 1876 and repeated in 1890 for the
Royal Coal Dust Commission, and Mr. William Galloway's
experiments (1876-80), led these men to the conclusion
that the fine dust of certain inflammable coals was capa-
ble of violent explosion when ignited by a flame of suffi-
cient volume and intensity, as, for example, the flame of
a gas explosion or the flame of a blown-out shot. The
presence of the smallest amount of gas both assists the
ignition of the dust and increases the force of the explo-
sion. These experiments, however, have not shown that
gas is necessary before an explosion of dust can occur.

ii6. An Extinctive Atmosphere. — Air is extinctive when
it fails to support flame; the flame is extinguished for the
want of sufficient oxygen. The flame may be that of a
candle, a lamp burning oil, or the flame of burning gas,
but the effect is the same for the same kind of flame re-
gardless of its size. The subject of the extinction of flame
by various atmospheres has been carefully investigated by
Prof. Frank Clowes, with the result that he has tabulated
the extinctive atmospheres for candle, oil-fed, and gas-fed
flames in three types, as follows :

MINE AIR 13d

1. A residual atmosphere, remaining when the flame dies
out in the products of its own combustion in a closed space ;

2. An atmosphere formed by adding carbon dioxide to
the air till the flame was extinguished immediately upon
immersion;

3. An atmosphere formed by adding nitrogen to the air
till the flame was extinguished immediately upon im-
mersion.

While information of this nature is suggestive and help-
ful in its application to mining, it represents but single
instances of unadulterated atmospheres, which are never
realized in mining practice. The information has a greater
value in showing, as Prof. Clowes no doubt intended it
should, the extinctive effect of the same atmosphere on
different flames, thus showing some flames more tenacious
or persistent than others. This has a relative value with
respect to candles and lamp flames using wicks or gas jets,
but there would be danger in assuming that the same
atmosphere would be extinctive of the flames of these
gases, burning freely in the atmosphere, .which they dilute,
instead of burning from a jet. This will be apparent
from the comparison it is possible to make with respect
to methane burning from a jet (Table 16), and an in-
flammable mixture of methane and air (Table 17), burn-
ing freely in its own atmosphere.

Table 17 has been computed by the author from data
given by J. W. Thomas, with respect to the extinctive
effect of gases on explosive mixtures of methane.

It is significant, in comparing the atmospheres extinctive
of methane burning at a jet (Table 16) with the corre-
sponding non-explosive atmospheres produced by adding
carbon dioxide and nitrogen respectively to methane, at
its most explosive point (Table 17), to observe that the

140

MINE GASES AND EXPLOSIONS

Table 16

residual and artificial atmospheres extinctive of

candle, oil-fed, and gas-fed flames. clowes

IHuminant

Extinctive Atmospheres

Residual
Atmospheres

Artificial Atmospheres

Carbon Dioxide
Added

Nitrogen
Added

CO2

Candle

Paraffin oil

Alcohol, absolute

" , methylated. . .

Colza and paraffin,!

equal parts J

15.7
16.6
14.9
15.6

16.4

81.1
80.4
80.7
80.2

80.5

3.2
3.0
4.4
4.2

3.1

18.1
17.9
18.1
18.3

17.6

68.5
67.8
68.5
69.3

66.6

13.4
14.3
13.4
12.4

15.8

16.4
16.2
16.6
17.2

16.4

83.6
83.8

83.4
82.8

83.6

Methane

Olefiant gas

15.6

82.1

2.3

18.9
15.5
16.0

8.8

71.6
57.6
60.6
33.3

9.5
27.2
23.4
57.9

17.4

13.2

15.1

6.3

82.6

86 8

Carbon monoxide

Hydrogen

13.4
5.5

74.4
94.5

12.3

84.9
93.7

Table 17
composition of firedamp mixtures rendered non-explo-
sive or extinctive of their own flame, or incom-
bustible by the addition of certain gases

Effect

Composition of Mixture

Gas Added

CH4

CO2

Carbon dioxide

Nitrogen

Non-explosive

t <
Incombustible

16.6
16.2
17.4
14.7

62.6

75.7
65.9
55.8

8.3

8.1

16.7

29.5

12.5

Methane

....

jet of gas was extinguished by 9.5 per cent, of carbon
dioxide, the oxygen being depleted only to 18.9 per cent.
On the other hand, the firedamp mixture was only ren-
dered non-explosive by 12.5 per cent, of carbon dioxide,

MINE AIR 141

while the oxygen was depleted to 16.6 per cent. When
nitrogen was added the depletion of the oxygen to 17.4
per cent, extinguished the burning jet, while a depletion
of the oxygen to 16.2 per cent, only made the firedamp
non-explosive. In either of these cases, a much wider
difference would result if the firedamp mixture were to be
made incombustible or extinctive of its own flame. This
is clearly shown in the case of methane (Table 17), where
the depletion of the oxygen by the addition of methane,
in excess, to firedamp rendered the mixture non-explosive
at 17.4 per cent., but it required a still further depletion
of the oxygen to 14.7 per cent, to make the mixture
incombustible or extinctive of its own flame. It will be
readily observed that this bears directly upon the extinc-
tion of the flame of a gas explosion.

117. A Dangerous Atmosphere. — An atmosphere may
be dangerous owing to its inflammability, or its near ap-
proach to an explosive condition, caused by the presence
of gas or dust or both, or owing to the presence of poison-
ous gases. It has been explained (Art. 115) that a non-
explosive mixture may be rendered explosive by reason
of a surrounding atmosphere containing carbon monox-
ide or dust from which this gas may be generated. A
dusty atmosphere always increases the explosiveness of
the mine air in proportion to the fineness and inflamma-
bility of the coal. The influence of heat and pressure in
increasing the explosiveness of gaseous mixtures has been
fully explained (Art. 115), and need not be referred to
here further than to say that it requires sometimes but a
very slight concussion of the air, such as might result from
the closing of a mine door, or a fall of roof, or an ordinary
blast in shooting coal to precipitate trouble. These sensi-
tive conditions depend always as much on the character

142 MINE GASES AND EXPLOSIONS

of the coal as on the gaseous condition of the air, except
only when considering highly explosive firedamp mixtures.
Safety under these conditions lies only in vigilance and
the enforcement of strict regulations designed to safe-
guard all the operations of the mine.

A quotation from Dr. Haldane, relating to the physiologi-
cal effects of carbon monoxide when breathed in small
quantities, will show that the danger of such poisonous
gases in the mine air is not realized as fully as it should
be by miners, who become too accustomed to the effects
described to be at all apprehensive of them. Dr. Haldane
is quoted as saying that .2 per cent, of carbon monoxide
may prove fatal if breathed over an hour, and .1 per cent,
breathed for the same time may disable a man (this
amount will shortly render the movements of a mouse
sluggish and his walk unsteady) ; .05 per cent, breathed for
several hours may cause fainting or dizziness on exertion,
and anything over .02 per cent, will after some time reduce
a man's power to perform work.

Young men generally stand the effects of this gas bet-
ter than older men, and strong men better than weak
men. The depletion of the oxygen in the mine air in-
creases the toxic effect of the gases and renders the
atmosphere of the mine dangerous or even fatal when it
would otherwise be safe. For example, in pure air with
a normal proportion of oxygen the least percentage of
carbon monoxide producing fatal results when breathed
by a healthy person for about one minute is stated as .5
per cent. (Table 18) ; but when the oxygen is depleted to
10 per cent, in the air breathed, .05 per cent, of carbon
monoxide may produce fatal results (Art. 92). This
will sufficiently emphasize the danger of breathing such
atmospheres.

MINE AIR 143

ii8. A Fatal Atmosphere. — A fatal atmosphere is gen-
erally understood as being one that will produce fatal
results on an average person, when inhaled for a short
time only; there is, however, no distinct line of separa-
tion between a dangerous atmosphere and a fatal one.
The term, as used in mining, relates to poisonous air and
not to explosive conditions, although the latter may prove
as fatal as the former. There are two general types of
fatal atmospheres, those rendered poisonous by the pres-
ence of small quantities of a poisonous gas or gases, and
those rendered irrespirable by the addition of a consider-
able amount of some gas that will not support life. The
fatal effect in the latter case is due directly to the dilu-
tion of the atmosphere and the consequent depletion of
the oxygen below the point required for maintaining the
vital functions. Methane produces a very slight if any
other effect, and nitrogen no other effect than that of a
diluent of the air, neither of these gases being poisonous.
Carbon dioxide is, for some reason not well understood
(Art. 94), more harmful than the two gases just mentioned.
Though not usually classed as a poisonous gas, it produces
fatal results with a less depletion of the oxygen than the
other gases. The following table -gives the least percent-
ages of carbon dioxide, nitrogen, and methane that when
added to pure air produce atmospheres that may be con-
sidered as fatal. To this table is also appended the per-
centages of the poisonous gases carbon monoxide and
hydrogen sulphide that are generally accepted as being
the least percentages producing fatal results in a brief
period of time, in otherwise good air.

Fatal results are produced more quickly on animals
than on men exposed to the same atmosphere. It has
been estimated that a mouse is affected in about one-

144

MINE GASES AND EXPLOSIONS
Table 18

COMPOSITION OF FATAL ATMOSPHERES, SHOWING LEAST PER-
CENTAGES OF THE PRINCIPAL MINE GASES PRODUCING
FATAL RESULTS IN OTHERWISE GOOD AIR

Gas Added

Composition of Mixture

CH4

C02

Carbon dioxide

17.1
7.0
7.0

64.9
93.0
26.5

m.h

18 0

Nitroffen

Methane

Carbon monoxide Least percentage fatal to life, . 5 per cent.

Hydrogen sulphide *' " ** ** ** 1.0 "

twentieth of the time required to produce the same effect
on a man. For this reason a mouse carried in a small
cage, when entering what may be suspected as a dangerous
atmosphere, serves as a safe index of the toxic effect
of the gases. There is also a considerable difference in
persons in this respect. A strong, healthy person may
be revived after being exposed for a long time to an
atmosphere that proves fatal in a less time to a person of
weak constitution or having a weak heart. Where water
is at hand, a wet handkerchief placed in the mouth, or
bound over the mouth and nose, is of some help in post-
poning the ill effects of the gas. It must be remembered
that the continued burning of the lamps is not a safe
index of pure air, since a lamp may burn brightly in an
atmosphere that is at once fatal to life; and again, lights
may be completely extinguished in an atmosphere where
there is no immediate danger (Art. 94).

In a mine explosion, where the incandescent carbon re-
sulting from the ignition of the coal dust suspended in the
air acts to reduce the carbon dioxide already produced

MINE AIR 145

by the explosion or existing in the mine workings, large
quantities of carbon monoxide are formed (Art. 112), the
action being accompanied by the absorption of heat. The
afterdamp produced under these conditions is extremely
poisonous, and in some instances almost instantly fatal
when breathed. Men have dropped in such an atmos-
phere almost as if shot.

CHAPTER V
MINE EXPLOSIONS

119. The term mine explosion describes that class of
accidents that is characterized by a more or less violent
disturbance of the mine air, together with the attendant
destruction of life and property, as the result of the
ignition and explosion of gas or fine dust contained in the
mine air. Mine explosions are of three general types,
embraced under the following heads:

1. Gas explosions;

2. Dust explosions;

3. Explosions of gas and dust combined.

A gas explosion possesses certain characteristics that
differ materially from those of a dust explosion, and make
known the nature of the occurrence and point to its pos-
sible or probable cause. The subject of mine explosions
is complicated by many dependent conditions that require
the most careful study and consideration to enable the
mind to comprehend what may take place in the workings
of a mine at the fatal moment.

120. Inflammable Mine Gases and Material. — ^The in-
flammable mine gases are methane or marsh gas, olefiant
gas (ethene), ethane, carbon monoxide, and hydrogen
sulphide; these have been fully described in the preceding
chapter. Each of these gases forms with air a mixture
that is inflammable or perhaps explosive, depending on

146

MINE EXPLOSIONS 147

the proportion of air present. Besides these gases it is
not uncommon for the rocks of the coal measures to be
impregnated, often to the point of saturation, with bitu-
men, petroleum, or naphtha; and these, according to the
theory of an eminent English expert, Mr. James Ash-
worth, may vaporize so rapidly when driven out from
the strata under the high pressure to which they are
subject, as to satisfactorily account for such outbursts as
the one that occurred at Mine No. 1, Morrissey, B. C,
November 18, 1904, when the main entry was suddenly
filled solid with fine coal for a distance of 450 feet from
the face and 14 men were suffocated. Although it was
estimated that fully 5,000,000 cubic feet of gas was given
off in this outburst, every light was extinguished with-
out ignition of the gas taking place. Mr. Ashworth
ascribes this outburst to the vaporization of the petroleum
or rock oil, as it is sometimes called, and naphtha impreg-
nating the strata. However this may be, it was a re-
markable instance of an outburst of gas or vapor so sud-
den and of such volume that the air of the mine did not
serve to dilute the gas to explosive proportions, and
every lamp was instantly extinguished.

121. Ignition of Gases. — The ignition of an inflammable
gas takes place whenever its temperature, at any point,
is raised to what is called th.e temperature of ignition for that
gas, and maintained a sufficient length of time in the
presence of air or oxygen. The ignition of a gas is always
accompanied with the production of flame, which as
quickly disappears whenever the temperature at a given
point falls below the temperature of ignition of the gas.
For this reason a flame cannot touch the surface of cool
metal, but there is always a thin film or layer of cooled gas
void of flame between them. It was the knowledge of

148 MINE GASES AND EXPLOSIONS

this fact that led Sir Humphry Davy to surround the
flame of a safety lamp with a wire gauze (Art. 148).

The ignition of a gas requires both heat and oxygen
and in some cases moisture, as in the case of carbon
monoxide gas, which cannot be ignited in perfectly dry air
except at a very high temperature. In other cases the
temperature must be maintained at the point of ignition
for a certain length of time before the gas will fire. For
example, the temperature of ignition of firedamp (methane
and air) is 1,200° F. (Table 19), but at this temperature
a time of 10 seconds is required to ignite the gas when
pure or unmixed with other gases. At a temperature of
1,800° F. the time required for the ignition of pure fire-
damp is but 1 second, while at still higher temperatures
only a fraction of a second is required.

The ignition of a gas depends on such a local concentra-
tion of heat, under conditions favorable to combustion,
that the temperature of ignition is reached in the com-
bustible itself. The intensity of the source of heat has
much to do in producing this result. For example, a
firedamp mixture that is only irvfiammaUe when ignited
by a flame of low intensity, is found to be explosive when
fired by a flame of greater intensity or by an electric
spark. Ignition of a gas has also been found to occur
more readily when fired from below than when fired from
above. Gas in a tube, open at both ends, may burn
quietly from the top of the tube, but explode if ignited
from below, owing to the admixture of air and more
rapid upward ignition of the gas.

Ignition supposes a rapid combustion of the body
ignited, and may or may not be accompanied with flame,
which is the intensely heated vapor or gas produced by
the combustion. The ignition of a gas, however, may

MINE EXPLOSIONS \ 149

generally be considered as producing flame. Tlie^ following
table gives the temperatures of ignition of the^ common
mine gases. The temperatures of ignition of bot^^h hydro-
gen sulphide and olefiant gas are much lower \'\'han the
other mine gases. ^\

Table 19 \

temperatures of ignition of the inflammable mine | gases

Oas

Methane

Carbon monoxide

Hydrogen

Hydrogen sulphide

Olefiant gas

Ethane

Some interesting deductions may be drawn from t^e
instructive experiments performed by Prof. H. B. DixonV
of the University College, Manchester, and a member of the'-
Royal Coal Dust Commission. A mixture of 1 volume of
marsh gas and 13 volumes of air failed to explode in a glass
tube I inch in diameter and about three feet long, while a
mixture of 1 part of the gas to 12 parts of air likewise
failed to explode in a tube of the same length and
J inch in diameter, these results being due to the cooling
effect of the walls of the tubes on the burning gas. The
heat developed in the tube was not sufficient to cause
the rapidity of combustion necessary for an explosion.
In a measure this illustrates the conditions in many mine
workings, especially in thin seams. While it is possible, in
the larger volume of the airways of a mine, for gas to ignite
when in contact with flame, yet the cooling effect of the walls
of the airways may often prevent, and probably in many
cases does prevent, the initiation of a destructive explosion.

150

MINE GASES AND EXPLOSIONS

Pressure assists the ignition of a gas by increasing its
power to /absorb heat. The absorptive power of air and
gases va/ies greatly for different gases under the same
pressure/ and for the same gas under different pressures.
In relat/on to the ignition of gas in mines, it is a signifi-
cant ff/ct that the gases known as the inflammahle mine
gases all have high absorptive powers, which increase rapidly
with the pressure of the gas. For example, taking the
absorptive power of air under a pressure of 1 atmosphere
at sea level as unity, that of olefiant gas is 90 for a pressure
equal to 1 inch of mercury, and increases to 970 for a
pressure equal to 30 inches of mercury. Thus at ordi-
nary atmospheric pressure at sea level, olefiant gas absorbs
970 times the quantity of heat absorbed by air under the
same conditions. The following table gives the relative
absorptive powers of some of the mine gases referred to air
aLs unity, and is suggestive in connection with the ignition
of those gases that are inflammable :

Table 20
absorptive power of mine gases

Gas

Air

Oxygen

Nitrogen

Hydrogen

Carbon dioxide

Nitrous oxide

Methane

Sulphurous acid gas.
Olefiant gas. .

Relative Absorp-
tion of Heat,
(Barom. 30 in.)

1
1

90
355
403
710
970

Pressure likewise concentrates the explosive elements,
bringing the molecules of gas and air closer together, and
increasing the heat energy developed per unit of volume.

MINE EXPLOSIONS \ \ 151

122. Temperature and Volume of Flame. — The ten^pera-
ture of flame, like the temperature of combustion (Art* 69),
is a variable factor, being even more indeterminate than
the latter, owing to the large and unmeasurable addition
of air. The fact is well known that the temperature of a
flame is not uniform throughout, there being different
stages and degrees of combustion taking place in different
portions of the flame; but what is understood as the
calculated or theoretical temperature of a flame is the cal-
culated temperature of the expanded products of com-
bustion, assuming no admixture of air other than that re-
quired for the complete combustion of the gas burned.
It is true this condition may only be realized at certain
points in a flame, but such a condition is most apt to be
fulfilled in a mine explosion, where the supply of air is
limited. The calculation of the flame temperature for
methane or marsh gas mixed with air in such proportions
as to produce complete combustion, the firedamp mix
ture being then at its most explosive point, has been ex-
plained in Article 69. This temperature is 4,173° F.;
that of carbon monoxide is found in a similar manner to
be 5,287° F., and that of hydrogen burning in air about
6,500° F. All of these temperatures, however, fail to be
realized in practice, owing to various causes, but chiefly
because the reaction that actually takes place is not cor-
rectly expressed by the chemical equation used.

The usual estimated temperature of marsh gas burning
in air is about one-half of the calculated value or, say,
2,000° F.; that of carbon monoxide about 2,500° F., while
the flame temperature of hydrogen is seldom estimated
above 3,600° F. The uncertainty in regard to the calcu-
lated temperatures of flame is due to the fact that much
is still to be learned of the manner in which the disso-

152 MINE GASES AND EXPLOSIONS

ciation and recombination of the atoms takes place.
Becquerel estimates the temperature of the alcohol
flame to be 2,200° F.; Lewes places that of the tip of a
tallow candle at 2,370° F.; Bunsen has found the tem-
perature of the oxyhydrogen flame to be 5,150° F.

Attention was called in Article 69 to what is usually
estimated as the volume of flame produced by the ex-
plosion of a body of firedamp at its most explosive point.
The volume of this flame was found to be practically
10 times the volume of the original firedamp mixture,
depending, of course, on numerous modifying conditions.

123. Heat Energy of Combustibles. — A brief glance at
the heat energies developed by the burning of 1 pound
each of different combustibles will be of interest and help-
ful by way of suggesting their relative importance in con-
nection with mining.

Table 21
'" heat energy of different combustibles

Combustible

Black blasting powder. . . .

Gunpowder

Guncotton

Nitroglycerin

Coal (anthracite), average, ,
Coal (bituminous), average.

Carbon

Methane (CHJ

defiant gas (C2HJ

Carbon monoxide (CO).. . .

Energy per Pound,
Foot-tons

360
500
750
1,100
4,800
4,600
5.657
9,146
8,302
1,682

It is observed from the above table that a very much
greater energy is stored in a pound of carbon or a pound
of marsh gas than in an equal weight of the most powerful
explosive. Abel explains that this is probably owing to
the fact that the explosive contains its supply of oxygen

MINE EXPLOSIONS 153

within itself, while carbon, coal, and other combustibles
draw their supply from the air. Much of the power of the
explosive is undoubtedly consumed in setting free the
oxygen contained in its ingredients. It is evident, there-
fore, that whenever the conditions in a mine are such as
to burn any considerable body of firedamp, or fine coal
dust suspended in the air, an enormous explosive effect
may be produced, the consequences of which it is hard to
fully realize. Berthelot has drawn attention to the fact
that the proper basis of comparison of the force developed
by different explosives is afforded by the product of the
volume and temperature of their gaseous products. Since
different proportions of the heat energy are absorbed by
the varying products of the combustion in each case, the
heat energy of a combustible is not the measure of its ex-
plosive force, but the volume and temperature of the
gaseous products, as stated above. Another authority
has discriminated between what he has termed explosive
force and explosive effect, considering in the latter term the
element of time, or the rapidity with which the combus-
tion that causes the explosion takes place.

The foregoing makes clear the fact that all combustible
material is explosive to a greater or less degree, depending
on the conditions that tend to accelerate or retard its rate
of combustion. This is a significant fact with respect to
fine coal dust held in suspension in the mine air and
acted upon by a flame of considerable volume and intensity.
The combustion of the dust, under these favorable con-
ditions, may and often does take place with explosive
rapidity. Ordinary black blasting powder yields on ex-
plosion 360 times its volume of gaseous products, measured
at 32° F., and a barometric pressure of 29.92 inches,
while the temperature of the explosion will not much

154 MINE OASES AND EXPLOSIONS

exceed 3,600° F. Gunpowder yields on explosion 280
volumes of gas measured at the same temperature
and pressure, while the temperature of its explosion is
practically 6,000° F. Nitroglycerin yields 13,000 volumes of
gas and produces an initial temperature of about 14,000° F.
Coal dust may yield 2,200 volumes of gas and a tem-
perature of 8,600° F. Marsh gas yields but one. vol-
ume of gaseous products and a temperature of 5,840° F.;
carbon monoxide yields but 85 per cent, of the original
volume of gas and a temperature of 7,400° F. The above
data all refer to explosion in a confined space, or to the
initial temperature of the explosion before expansion has
taken place.

124. Spontaneous Combustion. — When combustion
occurs in material as a result of the natural development
of heat without an apparent cause, the phenomenon is
called spontaneous combustion. This is a common occur-
rence in some coal mines, particularly in seams of bitu-
minous coal containing pyrites or sulphide of iron. The
disintegration of the pyrites in presence of moisture is
accompanied with the evolution of heat due to the chem-
ical action. While this process of itself could not ordi-
narily develop sufficient heat to start combustion in the
coal, it assists the breaking up of the coal and the ex-
posure of fresh surfaces for the absorption of oxygen by
the coal. Prof. Vivian B. Lewes of the Royal Naval Col-
lege, Greenwich, attributes the spontaneous ignition of
coal in bunkers to the absorption of oxygen from the air
by the coal. This absorption of oxygen is common to
the finest coal dust, which is thereby rendered more in-
flammable and dangerous (Atkinson). In the coal the
absorbed oxygen is brought into direct contact with -the
volatile hydrocarbons of the coal, and chemical action at

MINE EXPLOSIONS 155

once takes place with the production of heat. Under
favorable conditions the process thus started soon be-
comes self-supporting, and it is not long before the ignition
of the coal takes place, followed sometimes by the ignition
of the carbon monoxide produced.

It has been suggested^ with much reason, that the move-
ment of the strata incident to the extraction of the coal
from a seam, accompanied as it naturally is with the evo-
lution of heat, contributes its share toward spontaneous
combustion occurring in abandoned mine workings.

125. Gob Fires. — These may be the direct result of the
spontaneous ignition of fine coal and slack in the mine
waste. The subject is of importance here only with re-
spect to the gases produced and the resulting increase
of danger in the workings. Carbon monoxide is produced
in considerable quantity where the fire has become deep-
seated and the combustion has eaten its way well under
the gob, especially where the circulation of the air is slow.
In a seam generating marsh gas, a gob fire is a serious
menace to the safety of the mine, owing chiefly to the car-
bon monoxide produced increasing the explosive condition
of the mine air. Moisture in the strata is favorable to
the rapid extension of a gob fire.

The fine dust of many inflammable coals ignites at
remarkably low temperatures; the temperature necessary
for spontaneous ignition will depend on the nature of the
coal, the fineness of the dust, and its exposure to the air.
This temperature is variously given as 356° F. (Fayal),
284° F. (Bedson), the difference being probably owing to a
difference in the above stated conditions. It is certain,
however, that deposits of fine dust in the mine airways and
workings may be easily ignited from causes that would
hardly be suspected of producing ignition. It has been

156 MINE GASES AND EXPLOSIONS

proven by experiment that, under certain conditions,
an incandescent lamp gives out heat sufficient to inflame
light combustible material with which it may be in contact.

A recent fire that occurred at Littleburn Colliery was
caused by a workman laying a 16-candle-power electric
lamp for 15 minutes on a heap of fine coal dust in an
elevator hole, which he was cleaning out in readiness for
the following day. The lamp had been removed and three
hours later smoke was observed coming from the hole.
To establish the fact that fire could result from this cause
two experiments were performed. A 16-candle-power
lamp was laid in a heap of fine coal dust, the dust slightly
covering the lamp. Smoke came from the dust in three
minutes after the current was turned on, and eight minutes
later the bulb of the lamp collapsed owing to the intense
heat. The lamp was then withdrawn and three hours
afterward the coal was a mass of dull- red fire. When the
lamp was laid loosely on top of a similar heap of dust
smoke came from the coal in eight minutes, and seventeen
minutes later the heat was sufficient to melt the glass and
again the coal was fired as the result* The ignition in
each of these cases was greatly assisted or made possible
by the oxygen absorbed by the fine dust from the air.

126. Treatment of Gob Fires. — There should be no delay,
as this will greatly increase the trouble. The presence of
the fire in its first stages is made known by a peculiar
odor, which an experienced miner is quick to detect.
The treatment in any case will depend on the stage of
progress of the fire. Briefly, a small incipient fire should
be located and loaded out, and every vestige of the heated
material removed from the mine. Water, unless a suf-

* Trans. I. M. E., Vol. XXIX, page 294.

MINE EXPLOSIONS 157

ficient quantity be used, will generally make the matter
worse after a time. Water can be used with good effect
in a strong air-current; a good circulation of air is one of
the best preventives of such fires, since the cooler air of
the current reduces the high temperature of the workings
and carries away the gases generated by the combustion.
When the fire has been started by the accidental ignition
of gas in the floor, and the flame has drawn back under the
gob, it will be necessary to first extinguish the gas. It
may be possible to do this by exploding a small stick of
dynamite close to the gob, the concussion of the air often
being sufficient to put out the flame. When the gas has
been extinguished the trouble will cease, provided the
flame has not ignited fine coal and slack, in which case it
wall become necessary to remove the material till the seat
of the trouble is reached.

A gob fire in a room or chamber may sometimes
be isolated and extinguished by closing off the room by
building air-tight stoppings in all the openings thereto.
When closing off a room or a number of rooms, or a sec-
tion of a mine, in this manner, it is important to begin
the work of building the s-toppings at the return end, with
reference to the circulation, and work towards the intake
end of the section to be closed, in order to avoid the danger
of an explosion occurring from the accumulating gases
being forced out upon the lamps of the workmen. When
the intake end is kept open till the last, the gases that
accumulate in the affected area are driven back till the
last opening is closed. When the stoppings are to be re-
moved, the work should be commenced by slowly and
carefully taking down the stopping first put up at the
return end, giving the air pressure*sufficicnt time to crowd
the gases back towards this open eud, A small opening

158 MINE GASES AND EXPLOSIONS

may then be made in the stopping at the intake end. The
work shoukl progress slowly. The best built stoppings arc
never perfectly air-tight and therefore the gas always drains
towards the return end of the space enclosed. Flood-
ing a mine or any section of it in order to extinguish a
gob fire that has attained considerable proportions is always
the last resort, on account of the great loss of time and
damage resulting to the property. At times it happens,
however, that nothing else wull save the mine.

127. Causes of the Ignition of Mine Gases. — The possible
causes of the ignition of gas are numerous, the most com-
mon being the flame of a match or a naked lamp, a de-
fective safety lamp, a blown-out shot, or even an ordinary
safe shot if the gas has accumulated at the face, and the
sparking of electric wires or motors. It is claimed gas may
be ignited by the sparks from a steel pick or other tool. It
is a fact, however, the old steel mill and flint was used in
gassy mines as a means of light instead of lamps or can-
dles, in order to avoid the ignition of the gas. In one or
two instances it is recorded that gas was ignited by this
mill, which was in use before the invention of the safety
lamp. It is probable that a spark of burning steel will
not ordinarily ignite a pure firedamp mixture containing
no other gases. Pure firedamp has the peculiarity that a
certain length of time is required for the gas to be in con-
tact with the source of heat before ignition will take
place; this time decreases as the temperature is higher
(Art. 121). The presence of any gas, as hydrogen sul-
phide (H2S) or olefiant gas (C2H4) having a lower tem-
perature of ignition, or the presence of fine dust suspended
in the air, which dust may be ignited at a temperature of,
say from 300° to 350° ^F. (Art. 125), wHl greatly hasten
the ignition of the gas.

ML\E EXPLOSIONS 159

With regard to sparks causing the ignition of gas much
depends on the character of the burning spark as well as
that of the gas. For example, it is impossible to ignite
a pure firedamp mixture containing no other gas than
marsh gas with the glowing embers of a wood fire,
provided these are not fanned into a flame. The glow-
ing remains of an extinguished match held over a gas jet
fails to ignite the gas. A spark caused by a steel pick
striking a sulphur ball (iron pyrites) and due to the burn-
ing of a fine particle of the steel, or perhaps the burning
of hydrogen sulphide, seldom fails to ignite firedamp.
The term pyrites means fire producer. The sparks from
the copper brushes on the commutator of an electric
motor will not ordinarily ignite firedamp, unless dust or
some easily igni table gas is present to assist the ignition,
but when carbon brushes are employed, although sparking
may occur less frequently, the ignition of the gas is al-
most certain to take place, even when the firedamp is
quite pure. This is due to the greater intensity of the com-
bustion of the carbon spark.

The breaking of an incandescent lamp may or may not
be accompanied with the ignition of surrounding gas, de-
pending on . the character of the lamp, the manner in
which it is broken, and to some extent on the character
of the firedamp mixture and the temperature of the
mine air. These lamps are of two general types: a
lamp constructed for a low voltage and strong current
has a short thick filament, while a lamp designed for a
high voltage and weak current has a long thin filament.
If the filament is not broken, but remains intact when the
glass is shattered, it becomes almost dark for a moment
immediately after the glass is broken. This is due to the
cooling effect of the expanding air and gas that rush into

160 MINE GASES AND EXPLOSIONS

the vacuous space of the broken globe. In another mo-
ment the filament again glows and burns out with a spark
that is quite certain to ignite the gas. It is more common,
however, in mining practice, for the filament to be broken
by the same blow that shatters the glass. In this case
the breaking of the filament occurs during the brief mo-
ment of cooling when the filament is dark, and there is
therefore no sparking and no ignition of the gas takes
place. It is evident from this explanation, which con-
forms strictly to the results of careful experiments, that
the long slender filament of the high-voltage lamp is the
safer of the two for two reasons: it is more sensitive to
the cooling effect and also less liable to remain unbroken
when the glass is shattered and to cause sparking by
burning out in the air.

Gas issuing from a feeder under a great pressure and
with high velocity is not as susceptible to ignition at the
point of issue as farther away, where the gas has expanded,
owing to the cooling effect due to the expansion and the
lack of suflftcient oxygen to render the gas inflammable
before diffusion has taken place.

128. The Initiation of a Mine Explosion. — The ignition of
a body of gas in mine workings does not necessarily lead
to a mine explosion. Much, of course, depends on the
explosive character of thf^ firedamp, and the temperature
and the condition of the mine air and workings with respect
to gas, dust, and moisture, and the intensity and volume
of the fiame causing the ignition. These all may con-
tribute to cause an explosion that would not otherwise
be possible. Aside from these contributory causes, how-
ever, the initiation of a mine explosion requires a con-
servation of heat energy that is only possible, in the less
explosive mixtures, when the physical surroundings such

MINE EXPLOSIONS 161

as relate to the size or the immediate air-space of the
workings are favorable.

Another experiment performed by Prof. Dixon throws
much light on this part of the subject, and enables us to
surmise at least, in regard to what may and probably often
does occur when a body of gas is ignited in mine workings.
The experiment is a simple one : a glass tube about 4 feet
in length and | inch in diameter was filled with a fire-
damp mixture. The combustion, slow at first, vibrated
backward and forward in the mouth of the tube with
ever increasing intensity and amplitude, causing a flutter-
ing of the flame and agitating the air and gas in the tube.
This continued for a moment only, when suddenly the
flame darted the entire length of the tube, and the ex-
plosion was complete. In a mine the conditions affecting
the initiation of an explosion are manifold, and it is prob-
able there is every degree of variation in this respect, from
an instantaneous and blinding flash accompanying the
ignition of the gas, to a quiet flame sweeping majestically
forward and back, and finally developing its full explosive
strength within a radius of, say 20 yards from the initial
point where the ignition took place. In the latter case
the action is cumulative instead of instantaneous. Whether
or not an ignited body of gas in mine workings will amass
suflicient strength to manifest explosive violence is wholly
dependent on conditions such as those previously men-
tioned, relating to the character and temperature of the
gas-charged air and the immediate air-volume of the
workings.

129. A Gas Explosion. — The conditions that affect any
explosion in a mine are so numerous and varied that it is
difficult to point out the special characteristics that would
in every case distinguish an explosion of a particular class.

162 MINE GASES AND EXPLOSIONS

It may be stated, however, that in general a typical gas
explosion developes centers of greatest violence in those
localities where gas issues from the strata or tends to
accumulate. While it is true that, in any explosion of
gas or dust, violence is manifested wherever resistance is
offered to the free expansion of the air and gases produced,
yet in a true gas explosion the centers of violence are
more pronounced than in a dust explosion, and the lines
of force radiate in all directions from these centers, often
producing seemingly contradictory evidence of the direc-
tion taken by the main blast. A gas explosion will de-
velop its force anywhere within a radius of 20 yards from
any center, and the force so developed may be trans-
mitted with lightning rapidity to distant parts of the
mine, leaving scarcely a trace of evidence that the blast
has traveled over the intervening roadways or passages.

It is very rare that a mine explosion of any magnitude
is a simple gas explosion. It may originate as a gas ex-
plosion, caused by the ignition of a body of firedamp;
and at different points throughout the workings it may
develop the characteristics of a gas explosion, where the
flame ignites isolated bodies of gas; but in a large ma-
jority of cases, coal dust or blasting powder it may be
has played an important part in the propagation of the
flame and the maintenance of the high temperature of the
expanding gases that is necessary to keep alive the flame.

130. A Dust Explosion. — The essential feature of a dust
explosion is the manner in which it subsists. A dust ex-
plosion feeds upon material scattered in its path; it cannot,
therefore, choose its own path, but must follow those
passages that promise the largest sustenance, or afford
the most abundant supplies of dust and oxygen. Both
of these are necessary to the maintenance of the explo-

MINE EXPLOSIONS 163

sion. One of the characteristics of a dust explosion is
the large volume of combustible gas produced, and likewise
the large volume of oxygen required for the maintenance
of the combustion. As explained in Articles 69 and 122,
the flame temperature of carbon monoxide, which is the
chief product of a dust explosion, is much higher than that
of methane or marsh gas, and the expansion due to this
cause is relatively greater. Notwithstanding this, how-
ever, the high temperature of the expanding gases is
more easily maintained in a dust explosion than in a
gas explosion, owing to the distribution of the combus-
tible material and its abundance. With the high tem-
perature of the gases generated in a dust explosion all
that is required to produce flame in the mine workings and
passages traversed by the blast is oxygen, which can
only be obtained in a continuous supply in the direction
of the intake air-current. It is owing to this fact that one
of the distinguishing characteristics of a dust explosion
is the persistence with which it seeks the intake air and
feeding upon this air advances against the current. The
flame of such an explosion never extends very far in the
direction of the return air, because in this direction it is
quickly snuffed out in its own trail or the products of
its own combustion. The distance a dust explosion will
advance along the return airway of a mine will depend
on the volume of the workings, the size and condition of
the airways, and the amount of available oxygen in the
mine air in this direction.

The action of a dust explosion is not as sudden as that
of a gas explosion, for the reason that two operations are
necessary for its completion : first, the conversion of the
fine dust suspended in the air into carbon monoxide; and
second, the burning of this gas to carbon dioxide. Both

164 MINE GASES AND EXPLOSIONS

of these operations require oxygen. The following are
the important factors that determine the character of a
dust explosion:

1. The physical character of the dust; its fineness, in-
flammability, and porosity.

2. The free suspension of the dust in the air.

3. The temperature and hygrometric condition of the
air.

4. The volume and intensity of the flame causing igni-
tion.

5. The size of the openings or volume of the work-
ings.

6. The condition of the mine with respect to dust and
moisture.

While a dust explosion is less sudden in its action, it may
be fully as destructive or even more so than a gas explo-
sion. It is always more persistent, that is to say, it has a
greater power of continuance, owing to the high tenipera-
ture of the combustion and the wide explosive range of
the carbon monoxide, which is the chief component of its
gaseous products.

131. History of Coal Dust as a Theory. — Formerly all
large mine explosions were attributed to gas. The earliest
recorded mention of coal dust in connection with a mine
explosion occurs in an account of the Wallsend Colliery
explosion, September 3, 1803, given by Mr. Buddie, a
North Country viewer, England. In this explosion 13 men
and boys were kifled. The narrator in describing the
explosion states: ^^The survivors more distant from the
point of the explosion were burned by the shower of red-
hot sparks of the ignited dust driven along by the force
of the blast." In an article written by Robert Bald, a
distinguished mining engineer of Scotland, and published

MINE EXPLOSIONS 165

in 1828, the possible ignition of coal ciust by a blast of
flame was ably discussed.

That the dangerous nature of coal dust in connection
with mine explosions was known and recognized at this
time is plainly shown by the report of Professors Faraday
and Lyell, made in 1845 to the Home Office, regarding the
fatal explosion at the Haswell Collieries, September,
1844. In relation to coal dust the report reads as follows:
^'In considering the extent of the fire from the moment
of the explosion, it is not to be supposed that firedamp
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. 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 ex-
amined with the glass it presented the fused round form
of burnt coal dust, and when examined chemically and
compared with the coal itself reduced to powder it was
found to be deprived of the greater portion of the bitumen,
and in some instances entirely destitute of the same. There
is every reason to believe that much coal gas was made
from this dust in the very air itself, of the mine, by the
flame of the firedamp, which raised and swept it along, and
that much of the carbon of this dust remained unbumt
only from want of air."

Later, in discussing this explosion at the Royal Institu-
tion, Prof. Faraday said: ''The ignition and explosion of
the [firedamp] mixture would first raise and then kindle

166 MINE GASES A^D EXPLOSIONS

the coal dust that is always pervading the passages, and
these effects must, in a moment, have made the part of
the mine that was the scene of the calamity glow like a
furnace."

Following this, experiments were made in England and
in France for the purpose of ascertaining if possible the
precise nature of fine dust with respect to explosions, and
when the fatal Seaham explosion took place at Durham,
England, September 8, 1880, in which 164 lives were
sacrificed, there were found many strong advocates of
the dust theory. Among these were Sir Frederick Abel,
Henry Hall, William Galloway, J. B. and W. N. Atkinson
James Ashworth, and others. From this time dust took
the place of gas in the explanation of mine explosions.
There were yet, however, vital points of difference that
remained at that time and are still largely unsettled.

The experiments of Mr. Henry Hall, inspector of mines,
West Lancashire district, in 1876, and repeated for the Royal
Coal Dust Commission in 1890, were conducted on a
large scale in abandoned drifts and in shafts placed at his
disposal by their owners for the purpose. These experi-
ments will ever be memorable, owing to their importance
and to the care with which they were executed. The first
series of six experiments was performed in an old shaft 150
feet deep and 7 feet in diameter, April 30 to May 21 . A
cannon 2.5 feet long with a 2-inch bore was placed point-
ing upwards, at the bottom of the shaft. A quantity of
fine coal dust was thrown into the shaft from the top,
so as to saturate the air with the fine floating particles of
dust. Four explosions resulted from the six trials, all but
one of these causing a burst of flame into the air above the
mouth of the shaft. In one instance, when the dust failed
to ignite on the first discharge of the cannon, a second

MINE EXPLOSIONS 167

shot was fired two hours later, with the result that the
dust then remaining in the air exploded with considerable
violence. No dust had been added between these two
shots, but the ignition of the dust may have been assisted
by some carbon monoxide remaining in the shaft after
firing the first blast.

A second series of six experiments was made on June
26 in a shaft 390 feet deep and 18 feet in diameter. The
shaft was very wet, and the cannon was placed on a scaf-
fold at a depth of 300 feet from the surface, where a cross-
heading connected with another shaft. The experimental
shaft was in process of sinking. A coke fire was placed
on the scaffold to render this shaft an upcast. Owing
probably to the large volume of the shaft and the ample
space below and at the side for the expansion of the gases
produced by the blast there was no ignition of the dust
and no explosion resulted in any of these trials. Mr.
Hall attributes the failure to ignite the dust in these experi-
ments both to the wet condition of the shaft and its large
volume, which permitted the rapid expansion of the gases
and the dissipation of the heat energy of the blast. It is
quite probable, however, the carbon dioxide resulting from
the coke fire in this shaft played an important part by re-
ducing the explosiveness of the air in the shaft.

The third series of eighteen experiments occupied eight
days, and was performed in a shaft 630 feet deep and 8 feet
in diameter. As before, there were two shafts, in this case
only 63 feet apart. The cannon was placed on a scaffold
at a depth of 540 feet below the surface, where a small
brick-lined manway 10 square feet in area connected the
two shafts. At the foot of these shafts was a somewhat
larger connection, in which considerable water had ac-
cumulated. There was a current of air traveling down

168 MINE GASES AND EXPLOSIONS

the one shaft and up the experimental shaft at a velocity
of 100 feet a minute, which was nearly or quite saturated
with moisture. The five trials, July 30, resulted in three
explosions, giving flame in two of these extending 30 and 40
feet into the air. The six trials, October 17, gave three
explosions with flame above the shaft in one case only. The
seven trials, October 20, gave two explosions without flame;
but the seventh and last proved the most violent explosion
of all, the flame rising 60 feet in the air, accompanied with a
continuous roar and rush of flame that lasted 5 or 6 seconds.
Mr. Hall states that he was perfectly satisfied in these ex-
periments that there was no firedamp present in the shafts.
The analysis of the air passing through the shafts, taken
during the progress of the experiments, showed oxygen
20.50%; nitrogen 79.20%; carbon dioxide .15%; and sul-
phur dioxide .09%.

The questions still in dispute, however, are as to whether
or not a dust explosion is possible in the entire absence of
gas (CH4) ; whether or not a cloud of dust can be ignited
by the ordinary flame of a lamp; and whether or not any
system of sprinkling practicable in mining will avail to
arrest an explosion of dust in a mine when such an explo-
sion has once gained headway. To ascertain the true
relation of fine dust of any kind to mine explosions, and if
possible to clearly define the danger due to its presence
and suggest practicable means of dealing with the eVil,
important commissions have been appointed from time
to time, and elaborate experiments have been made by
the governments of England, France, Austria, and Belgium.
The results of these investigations are briefly summarized
below.

The French Firedamp Commission, led by the eminent
mining experts MM. Mallard and Le Cha teller in 1882

MINE EXPLOSIONS 169

rejected the idea that coal dust could play any important
part in a large mine explosion. Two years later, how-
ever, the Prussian Firedamp Commission in 1884, having
completed an extensive series of experiments at Saar-
brlicken, concluded that certain fine, inflammable dusts
when ignited by a blown-out shot carry the flame to con-
siderable distances beyond the limits of the dust deposits,
and produce explosive results in the complete absence of
any trace of firedamp, the resulting phenomena being
similar to those produced by other dusts in air containing
7 per cent, of firedamp. Also, any explosion of dust is
intensified by the presence of small proportions of firedamp
in the mine air.

In 1886 the English Accidents in Mines Commission,
after completing experiments and investigations covering
a period of seven years, reported in substance as follows :

1. The occurrence of a blown-out shot in a working place
where very highly inflammable coal dust exists in great
abundance may, even in the total absence of firedamp,
give rise to a violent explosion, or at least be followed by
the propagation of flame over very considerable areas,
and thus communicate flame to explosive mixtures in
distant parts of the workings.

2. The occurrence of a blown-out shot where but a
small percentage of firedamp exists in the air, in presence
of but slightly inflammable or a wholly non-inflammable
but very fine, dry, and porous dust, may cause an explo-
sion, the flame of which may reach other distant accumu-
lations of gas or deposits of inflammable dust, which in
turn being inflamed thereby may extend the disastrous
results to other mnre remote places in the mine.

An Austrian ccmmission appointed in 1885 to investigate
the causes of mine explosions, after conducting a large

170 MINE GASES AND EXPLOSIONS

number of experiments with almost every possible kind
and condition of dust, both with and without the admix-
ture of gas, made a final report to the royal government
in 1891 to the effect that nearly all kinds of coal dust were
ignited by a cartridge of 100 grammes (.22 lb.) of dyna-
mite lying loose. This small weight of explosive would
of course correspond to a much heavier charge in pro-
portion to the increased volume of the confined space
where the explosion might occur. It was further found
that the presence of but a small percentage of firedamp
in the air manifestly increased the sensitiveness of the
dust, so that a dust othei'wise not dangerous may give
rise to a disastrous explosion under these conditions. The
fineness and the dryness of the dust, not to say the dryness
of the air, was found by this commission to greatly increase
the danger of inflammation.

The Royal Commission on Explosions from Coal Dust
in Mines, commonly called the Royal Coal Dust Com-
mission, appointed in England in 1891, in their second
report in 1894, summarized the conclusions at which they
had then arrived as follows:

''1. The danger of explosion in a mine in which gas
exists even in very small quantities [proportions] is greatly
increased by the presence of coal dust.

"2. A gas explosion in a fiery mine may be intensified
and carried on indefinitely by coal dust raised by the ex-
plosion itself.

"3. Coal dust alone without the presence of any gas
at all may cause a dangerous explosion if ignited by a
blown-out shot or other violent [source of] inflammation.
To produce such a result, however, the conditions must be
exceptional and such as are only likely to be produced
on rare occasions.

MINE EXPLOSIONS 171

"4. Different dusts are inflammable and consequently
dangerous in varying degrees, but it cannot be said with
absolute certainty that any dust is entirely free from risk.

"5. There appears to be no probability that a dangerous
explosion of coal dust alone could ever be produced in a
mine by a naked light or ordinary flame."

132. The Coal Dust Theory.— Briefly stated the dust
theory assumes that the fine dust of any combustible ma-
terial held in suspension in the air and acted upon by a
flame of sufficient volume and intensity is either itself
consumed with explosive rapidity or distils gas that forms
an explosive mixture with the air. When the dust is in-
combustible it may still assist the explosion of otherwise
inexplosive gaseous mixtures by a catalytic action as will
be explained (Art. 134). The theory assumes that the
rapidity of the action and the force of the resulting explo-
sion are in direct proportion to the fineness and inflam-
mability of the dust. It supports the assumption that
the fine dust of any combustible material under these
conditions is explosive in an atmosphere that will support
the combustion, whether gas is present or not. It is
admitted, however, without argument that the presence
of an inflammable gas in the smallest quantity both assists
the ignition of the dust and increases the force of the ex-
plosion produced. On the other hand the presence of an
extinctive gas retards the ignition of the dust, and reduces
the explosive force, even to rendering the dust-laden
atmosphere inexplosive by reason of its presence.

The essential factors of any explosion are the presence
of a combustible in such form as makes combustion with
explosive rapidity possible, the presence of an atmosphere
that will support the combustion, and the maintenance of
a degree of heat at least above the temperature of ignition

172 MINE GASES AND EXPLOSIONS

of the combustible. Any condition whatever that lessens
the effectiveness of any of these factors reduces not only
the force of an explosion but the liability of its occurrence
133. The Percussive Theory. — The reasoning on which
this theory is based has been offered from time to time as
furnishing a satisfactory explanation of certain observed
facts relating to the practically instantaneous transmis-
sion of the fatal effects of an explosion throughout a mine.
The records of mine explosions abound with instances
in which the fatal blast was felt with equal suddenness
and violence in distant parts of the mine at the same
time. Other recorded instances show the practically
simultaneous explosions of gas in distant portions of the
mine, isolated from each other by long stretches of road-
ways and air passages that were found to bear no trace
of flame having passed through them. The percussive
theory assumes that a wave of compression imparted to
the air by the force of the initial explosion is transmitted
almost instantly to other portions of the mine, where
sufficient heat is developed by the resistance it meets to
cause the ignition of other bodies of gas accumulated
there. Experiments are quoted as proving that it is
possible to cause a spark by the sudden compression of
pure air in a glass cylinder by quickly forcing down a
tightly fitting piston. Mr. Joseph Dickinson, Her Majesty's
senior inspector of mines, Great Britain, stated in his evi-
dence before the Royal Coal Dust Commission (1891),
that he had with such a device struck a spark in pure air
fifty times, but that he could never get a spark twice from
the same air, it being necessary to recharge the instrument
with fresh air each time. An instrument was devised on
this principle, for the purpose of testing for firedamp in
mine workings, by Dr. Angus Smith, who supposed that

MINE EXPLOSIONS 173

it required from 1 to 2 per cent, of marsh gas in the air
to produce the spark, but this was found not to be the case.
Whether or not this illustrates what takes place on a larger
scale in a mine explosion can only be conjecture, but the
percussive theory has gained many strong adherents, prom-
inent among whom are Mr. Joseph Dickinson and Mr.
James Ashworth.

134. Character and Influence of Dust. — Dust possesses
both a chemical and a physical character, which affects its
inflammability and in other ways also determines the ex-
tent to which it is a dangerous element when suspended
freely in mine air. It has been shown by Sir Frederick Abel
and others that the finely divided dust of certain incombus-
tible substances as chalk and magnesia assists the explosion
of otherwise inexplosive gaseous mixtures. This was at
first attributed to the supposed action of the dust as a con-
ductor of heat or some other form of energy, but later was
explained as being due to a catalytic action of the dust on
the gas and air. However this may be, the fact has been
well established by the experiments of Dr. Broockmann,
Manager of the Royal Prussian Experimental Laboratory
at Bochum, Westphalia,, and by the observations of the
Messrs. W. N. and J. B. Atkinson, H. M. inspectors of
mines and others, that coal dust, especially fine coal dust,
absorbs a very considerable volume of oxygen from the
air. The Messrs. Atkinson discriminate between what
they term upper dust, or the dust accumulating on the
timbers and the sides and top of airways, and bottom
dust taken from the floor. It is claimed the upper dust,
which is lighter and finer than bottom dust, undergoes a
slow change by reason of which it is rendered highly com-
bustible and easily inflammable, possibly due to the ab-
sorption of oxygen from the air, but doubtless owing

174 MINE GASES AND EXPLOSIONS

largely to the impregnation of the dust with the oily and
sooty products of the incomplete combustion of inferior
grades of illuminating oils burned in the lamps or torches
in use- on these roads, as well as the disintegrating influence
of the atmosphere on the dust, and to the absorption of
oxygen combined.

Under the favorable conditions presented in a mine
the explosion of 1 pound of fine, inflammable coal dust sus-
pended in the air and subjected to the flame of a blown-out
shot or other explosion would produce a volume of carbon
monoxide gas equal to 31.5 cubic feet, measured at 60° F.,
and a pressure of 14.7 pounds per square inch, and this
gas disseminated in air would render explosive a maximum
volume of 2440 cubic feet of the mixture, measured at the
same temperature and pressure. It must be remembered
that any carbon dioxide gas formed by an explosion in an
excess of air may be again reduced by the intense heat
of the explosion, in contact with unburned incandescent
carbon (dust), to carbon monoxide (Art. 112), making
possible the theoretical conditions mentioned above, which,
however, could not be expected to obtain in any experi-
mental test; but the possibility is clearly shown.

135. Phenomena of Mine Explosions. — These are varied,
owing to the multitudinous conditions affecting the oc-
currence. In some instances the victims of a mine ex-
plosion have been stricken with death, as it were in a
moment of time, without warning. Men have been found
in postures that left no doubt of the utter absence of
alarm; some in the act of eating or drinking, others with
pick in hand engaged in mining the coal when the fatal
shock came. At other times there is no sudden and
violent shock, but a certain ominous disturbance of the
air, followed quickly by a rush of wind bearing dust and

MINE EXPLOSIONS 175

debris. The presence or absence of flame and the degree
of violence of the blast will be determined wholly by the
conditions relating chiefly to the character of the initial
explosion, the condition of the mine with respect to gas,
dust, and moisture, the quantity of air in circulation at the
moment of the explosion, and the volume and temperature
of the workings, size of openings, etc.

In studying the phenomena of mine explosions of
any considerable magnitude, it is important to remember
that air (oxygen) is as necessary to flame, as a degree of
heat sufficient to cause the ignition of fresh supplies of the
combustible. In the narrow confines of the mine passages
it is not only possible but highly probable that the projected
blast of gas, dust, and other combustible material often
traverses long distances at a temperature far above that
required for ignition, but with little or no accompanying
flame, being propelled by the powerful expansive forces
being developed within the cul de sac of the workings. At
some distant point in its path, or perhaps at the mine
opening, the contact of the overheated gases with a suf-
ficient volume of air causes a burst of flame. This condi-
tion is more apt to result from a dust explosion or a gas
explosion in which dust plays a prominent part than from
a simple gas explosion. It is evident that the mere absence
of any traces of flame or burning does not prove conclu-
sively, as is often claimed, that the main blast of the ex-
plosion did not pass that way. Again, the ignition and
explosion of seemingly isolated bodies of firedamp in por-
tions of the mine distant from the initial point of the ex-
plosion, and separated therefrom by a long stretch of road-
way apparently unswept by flame, does not prove a second
ignition from another cause. To explain such an occur-
rence it is not even necessary to resort to the theory of

176 MINE GASES AND EXPLOSIONS

ignition by percussion (Art. 133), although this is entirely
possible. Another possible cause of the ignition of such an
isolated body of gas is the effect of the concussion produced
in the air by the initial blast, upon the dust-covered'lamps in
other portions of the mine. The same concussion of the
air acting simultaneously on a dusty lamp and the gas-
laden air about it not only causes the lamp to flash (pass
its flame through the gauze), but renders the atmosphere,
for that moment, more explosive, owing to the increased
pressure on the air. Any one of these three causes may
produce the almost simultaneous ignition of bodies of fire-
damp that under ordinary conditions are isolated from each
other. Separate explosion centers may be thus developed
at different points throughout the mine when the con-
ditions are favorable.

The effect produced by concussion, on air containing an
ordinarily safe proportion of gas, by which an other-
wise safe atmosphere is rendered momentarily explosive,
and the simultaneous effect produced by the same cause
upon lamps, should be a warning against the common
practice of allowing but a slight margin of safety in respect
to the gaseous condition of the mine air.

A peculiar phenomenon of some dust explosions is the ex-
tinction of the flame of the explosion by reason of the thick
clouds of dust that fill the air and speedily consume all
the available oxygen. The atmosphere under these con-
ditions becomes a veritable sea of dust, which is found
afterward covering the floor in certain portions of the
workings to the depth of several inches. Men have been
found under these terrible conditions with the mouth and
nostrils packed tightly with the dust. The appearance
of the ignited dust of a small, local explosion has been
described by survivors as that of ''a shower of red-hot

MINE EXPLOSIONS 177

sparks." Where dust has been present in an explosion
in such quantities as to cause the extinction of the flame
of the explosion, the thick deposits of dust found after-
wards show a semi-coked condition, the particles of dust
being partly rounded. The dust is also found upon ex-
amination to have lost a portion of its volatile matter;
otherwise it is unchanged

In regard to the deposition of dust on the timbers in a
passageway traversed by the blast of an explosion there
is a variance in the experience of different writers. In
the report of Faraday and Lyell upon the Haswell Colliery
explosion, to which reference has previously been made
(Art. 131), it is clearly stated that the dust was deposited
on those faces of the pillars, props, and walls in the direc-
tion of and on the side towards the explosion. The Messrs.
W. N. and J. B. Atkinson in their book Explosions in Coal
Mines, page 25, state: "The deposit of dust on timber and
other things affords an indication as to the direction [of
the blast], which the writers think is usually misinter-
preted. . . . This matter was more fully investigated
at Usworth than at any of the other explosions. ... At
Usworth observations were made in more than twenty
instances. The direction of the blast was, in most of
these cases, not a matter of any doubt whatever. It
appears from these observations that dust either as dust
or as coke is generally deposited on the sides of the props,
etc., opposite to the direction of the blast."

The experience of the writer in the Cedar Mines ex-
plosion at Albia, Iowa, and in the Coal Creek explosion at
Fernie, B. C, Canada, in both of which coal dust played
a prominent part, would confirm the latter statement.
In each of these cases the dust was found on the lee of the
timbers, or on the side away from the blast. In this con-

178 MINE GASES AND EXPLOSIONS

nection, however, it should be frankly stated that so mani-
fold are the conditions relating to the blast, and the char-
acter of the deposited dust varies so widely in different
instances, that it is not only possible but probable that
dust may be deposited on either side of timbers, but will
then have a somewhat different character in each case.
In general the dust projected forcibly against the face of
timbers or other obstructions in the path of a blast, and
deposited thus on the side toward the blast, will be coarser
and harder than that deposited on the lee of such timbers
or obstructions. In any case, the thickness of the deposit
and the coked condition of the dust will depend on the
quantity of dust thrown into the air, its character, and the
character of the blast. The coking of the deposited dust
is often the effect of the return flame, which burns more
quietly and is hotter than the original blast. It may
happen that the same passageway is traversed, in opposite
directions, by two distinct blasts, originating from isolated
centers of explosion or by the flame due to the recoil of
the original explosion, and the resulting phenomena must
be judged in the light of these possibilities.

The extent to which coking is produced as a result of an
explosion will depend on the force of the blast, the in-
tensity of the flame, and the character of the coal and fine-
ness of the dust. The process is the same as what takes,
place in the ordinary coking of coal; the volatile matters
of the coal are expelled, leaving a hard, brittle, and more
or less fused residue. When coke is formed it is found after
the explosion deposited in most places where dust would
be deposited, but generally in larger quantities on those
timbers and faces of the coal more exposed to the action of
the flame. Coking is evidence, at the same time, of ex-
treme heat and a limited supply or the entire absence of

MINE EXPLOSIONS 179

oxygen m the atmosphere of the workings at the time of
the coking of the dust.

The recoil or the return flame of an explosion, as it is often
called, is an interesting phenomenon. As the first ex-
plosive blast sweeps through an entry or mine passage,
it leaves behind it a trail of hot and generally inflammable
gases, consisting chiefly of carbon monoxide and nitro-
gen. The immediate cooling of these hot gases causes
a depression or f aU of pressure in the entry, and, as a conse-
quence, air rushes in from the adjoining rooms or cham-
bers and other workings. Thus a fresh supply of oxygen
is furnished, and the flame having been arrested in its ad-
vance by the increasing effect of the depression behind
or by its own expansion and cooling, or other cause, starts
to burn back on its own trail. This second burning is less
rapid and violent but generally hotter than the first blast,
and often reaching lower down from the roof, even per-
haps lapping the floor. Most if not all of the available
oxygen of the mine air is now consumed, and naught re-
mains but the deadly afterdamp. In special cases where
more air finds its way to the place, a third but feeble burn-
ing may result, which, however, is rare.

136. Entering a Mine After an Explosion ; Rescue Work. —
The difficulties and dangers of this work will depend
much on the conditions with respect to the character of
the mine and the magnitude of the occurrence. Prompt,
intelligent action is required on the part of those outside
of the mine, upon the first intimation of trouble below
ground, and it is likewise necessary that any survivors in
the mine should display the same promptness, coolness,
and intelligence in their own behalf. Excitement is al-
most certain to result fatally, because an exhausted con-
dition of the body, and particularly of the lungs, cannot

180 MINE GASES AND EXPLOSIONS

long survive a rapid transition from breathable air to
an atmosphere of afterdamp. It is a matter of record that
in numerous large mine explosions from 85 to 95 per cent,
of the victims have been killed by inhaling afterdamp.
As suggested by Dr. Haldane in his report to the English
government on the causes of death in colliery explosions
and underground fires, many lives would often be saved
if the men remained in their working places instead of
rushing out on the airways, where certain death awaits
them. In this it will be necessary to be guided by sound
judgment based on an accurate knowledge of the movement
of the air and the location of the explosion. It would be
courting death to attempt to escape by an intake road
if the force of the explosion came from the direction of
the shaft or mine opening. In such a case the only hope
of flight would be by a possible circuitous route following
the return air. If this is not possible, safety should be
sought in some isolated district of the mine or section of
the workings that may be sealed off, and here, with lights
out and lying on the floor, assistance from the outside
should be awaited.

On the surface, a speedy call having been made for
volunteers and medical assistance, the ventilating appara-
tus is hastily examined and any necessary repairs promptly
and quickly made. It is important to observe closely the
effect produced by the explosion on the general circulation
of the mine as revealed by the condition of the upcast or
return air discharged from the mine, and the quantity of
air entering the mine. The explosion may have destroyed
the circulation so that practically no air is found entering
the mine, or the current may even be reversed.

While this is being done the safety lamps, tools, and
materials that will be required in the mine are prepared

MINE EXPLOSIONS 181

and brought to the entrance, where they will be in readi-
ness for use. From among the volunteers only the most
experienced and tried men should be chosen to enter the
mine. No one who is subject to heart trouble should be
chosen for this work. The rescue party thus formed is
divided into two squads or divisions, the one to act as an
advance or exploring party, and the other to follow as
closely as possible, completing the temporary repair work
of the first party and rendering all needed assistance to
hasten their progress.

The mine must be entered by the intake opening, and
no advance must he made ahead of the air-current. Each
party is placed in charge of a competent and experienced
person who is thoroughly familiar with the mine. Having
entered, the first party proceeds as rapidly as the circum-
stances will permit to explore the mine. Air-stoppings,
doors, brattices, and air-bridges have often been blown
down and must be replaced temporarily, or some form of
brattice constructed to carry the air-current forward.
The work of this kind performed by the first or exploring
party is of the most temporary nature, and is completed
by the second party following. The air-current is thus
strengthened against the accumulating afterdamp, which
must be slowly forced out of the roads into the return air-
way to permit the rescuers to advance. The greatest
caution is required to guard against roof falls, the ignition
of firedamp that may have accumulated since the ex-
plosion took place, and the even greater danger of being
overcome with the deadly afterdamp. In places the entry
ipay be completely or partially blocked by high falls of
roof, which must be passed over, as there is not time for
their removal. The lamps must be carefully watched,
especially on top of the falls, to ascertain the gaseous con-

182 MINE Oases and explosions

dition of the air at all points of the passages traversed by
the rescuers.

Owing to the fact, however, that lamps will continue to
bum in an atmosphere that is fatal to life (Art. 118), it is
necessary to observe more carefully one's breathing, pulse,
and general feeling. In the presence of poisonous gases,
particularly carbon monoxide, a rapid pulse and more or
less labored breathing is quickly followed by a weakness
of the limbs that in most cases produces immediate pros-
tration and utter helplessness or inability to move. It
was want of this knowledge that led to three of the ex-
plorers' lives being lost after the explosion at Penygraig
in 1880. When the leader of the explorers was advised to
return from the afterdamp, the last words he is known
to have said were that while the light would burn he could
live. A curious effect of afterdamp is that when a strong
man has worked until he feels weak, he becomes partly in-
toxicated and talkative. It is time then to return, and
when such a man reaches pure air he is sure to fall uncon-
scious. A good safeguard against being overtaken una-
wares by the poisonous afterdamp is to carry along a caged
mouse, which will show signs of prostration from the effects
of the gas and thus give ample warning in time to with-
draw to better air (Art. 92).

The symptoms of gas poisoning and the treatment of
persons overcome by gas has been fully explained in the
chapter on Mine Gases. Victims of gas poisoning should
not be removed too quickly from the atmosphere of the
mine to the outside air. Violent delirium often results
when the patient is brought to the surface too rapidly,
or a strong man who has withstood the effects of the gas
for a long time in the mine may fall unconscious on reach-
ing the surface. The loss of consciousness in the latter

MINE EXPLOSIONS 183

case is possibly due to a diminished flow of blood to the
brain the result of being hoisted to a higher and lighter
atmosphere, or to a change in the hygrometric condition
of the air.

There should be kept on hand at every mine such an
emergency outfit and such simple remedies and needed
supplies, splints, bandages, etc., as are liable to be required
for the immediate treatment of broken bones, burns, or
scalds, or persons overcome by gas, or suffering from
shock or loss of blood. There should be a good propor-
tion of the men distributed through the mine who have
more or less training and knowledge in regard to what is
necessary to be done to save life in case of accident, while
a specially trained corps of assistants should always be
available on the surface at the mouth of the mine. The
necessary ambulance outfit, including suitable stretchers,
blankets, and rubber coverings, should be always at hand
and ready for use. Special rescue apparatus such as head
coverings (Fig. 15) of different styles, together with tanks
or bags charged with compressed air or oxygen and worn
or carried by the user, have been employed with much
success, but ordinarily the mine passages are too badly
blocked to permit of the employment of a helmet such
as shown at (a).

The Courri^res disaster — France (1906) — has drawn
attention very forcibly to the use of breathing apparatus
in rescue work in mines. The observations and conclu-
sions of Dr. G. A. Meyer, Westphalia, who organized and
conducted a special rescue corps and rendered efhcient
service in the examination of the Courrieres mine, after
the explosion, are of particular value. In a paper re-
cently contributed to The Institution of Mining Engineers,*
* Trans. Inst. M. E., Vol. XXXI, p. 575.

184

MINE GASES AND EXPLOSIONS

Dr. Meyer describes the essential requisites of breathing
apparatus suitable for mine rescue work.

The earliest form of breathing apparatus was designed
(1853) by Prof. Theo. Schwann, Professor of Physiology at
the University of Liege, on the general principle estab-
lished by Regnault, namely, that the vitalizing power of

(a) Vajen-Baden Helmet (6) Shamrock (Meyer) (c) Detail of

Apparatus Mouthpiece

Fig. 15. — Breathing Apparatus — Rescue Work

air depends only on the removal of the carbon dioxide from
the air expired from the lungs, and replacing the oxygen con-
sumed in the oxidation of the impurities of the blood. Air
thus purified can be respired continuously without danger,
to the system.

It is estimated * that an adult in usual good health re-
spires, at rest, 263 cubic centimeters of oxygen per minute
or 15.78 liters per hour, and very v'olent exertion increases
this amount about eight or nine times. This estimate is
confirmed practically by a long series of experiments per-

* Investigations on the Supply of Air and the Conversion of Energy
in Cyclists. — Dr. Leo Zuntz, Berlin.

MINE EXPLOSIONS 185

formed in the Shamrock Mines, Westphaha, which showed
that a miner in the ordinary performance of work con-
sumes practically 2 Uters of oxygen per minute, corre-
sponding to a respiration of, say 600 cubic inches of air
each minute. These figures have formed the basis of the
calculation for determining the necessary size of the oxy-
gen cylinders of a breathing apparatus. The best forms
of breathing apparatus are supplied with two oxygen
cylinders, one of which is for use on the in-going trip in a
mine, while the other is held in reserve for a safe return
to fresh air. The oxygen is compressed to 120 atmos-
pheres, which multiplies the capacity of the supply cylin-
ders in the same ratio. On this basis each liter of tank
capacity permits of an hour's use of the apparatus.

The regeneration of the air was first attempted by the
use of hydrated peroxide of barium, which was expected
to absorb the carbon dioxide and liberate oxygen at the
same time. The amount of oxygen set free, however,
was found to be insufficient and some ozone was formed.
Later this absorbent was replaced by hydrated lime satu-
rated with a solution of caustic soda, which gave better
results and is still used.

The type of apparatus recommended by Dr. Meyer is
that shown at (6), Fig. 15, in which the oxygen is in-
haled through a tube held firmly in the wearer's mouth.
A nose clip is attached to the upper side of the tube and
two plugs of cotton wool soaked in vaseline are so ar-
ranged as to close the nostrils completely. This mouth-
piece, shown in section at (c), is an important feature of
the apparatus. It is constructed on the principle of the
injector, so as to prevent as far as possible the inhalation
of expired air that has not passed through the regenerator.
The exlialed air passing through the nozzle a is conducted

186 MINE GASES AND EXPLOSIONS

by the tube h to the regenerator worn on the chest. The
discharge of the exhaled air through the nozzle a, causes
a depression or partial vacuum in the tube c, conducting
fresh supplies of air to the mouth. The chief problem Hes
in the removal of the carbon dioxide from the air by bring-
ing the latter into regular contact with the caustic alkali
contained in the regenerator. The circulation of the air
through the apparatus must be accomplished without
niaking any demand on the respiratory muscles. The
apparatus requires about 2 J pounds of the alkali every
two hours.

The experimental observations of Dr. J. S. Haldane and
Mr. J. Lorrain Smith, led to the following conclusions:
(1) Respiration becomes noticeably more difficult when
the proportion of carbon dioxide in the air exceeds 4 per
cent., by addition; that is to say, when the oxygen of the
air is not depleted. (2) The continued breathing of air
containing more than 4 per cent, of carbon dioxide causes
headache and throbbing, followed by nausea. (3) No
ordinary excess of oxygen avails to overcome these effects
produced by an excess of carbon dioxide. (4) An insuffi-
cient supply of oxygen (excess of nitrogen) in the air
breathed causes a difficulty in respiration, which first be-
comes noticeable when there is but 12 per cent, of oxygen
present. There is excessive difficulty and a sense of suf-
focation when the oxygen falls to 6 per cent.

137. Mine Hospitals, Refuge Stations, etc. — Every large
well-equipped mine is now provided with a suitable and
comfortable hospital room underground (Fig. 16), where
any who may be injured or overcome by gas can receive
prompt treatment under favorable conditions. These hos-
pital rooms are supplied with hot and cold water, good air,
and means of regulating the temperature as required. In

MINE EXPLOSIONS 187

some cases they are provided with beds, Ughted by elec-
tricity, and heated by steam.

Since so large a number of the deaths resulting from
mine explosions are due to inhaling afterdamp, every
practicable means of avoiding this should receive care-
ful attention. In this connection it was suggested some
time ago that in all fiery and dusty mines there should

Fig. 16.— An Underground Hospital

be provided in the mine workings, approved stations, which
should be connected with an air-compressing plant on the
surface by adequate pipe lines for supplying sufficient air
to keep alive a large body of men who might find their
way to such station, in case of accident shutting off the
avenues of escape and destroying the circulation of air
in the mine. It was suggested that the pipes for: the

188 MINE GASES AND EXPLOSIONS

supply of air should be laid just beneath the floor of
the mine roads to protect them against roof falls. The
end of each pipe line should be provided at each station
with a tap, which should be kept closed, and opened only
by those occupying the station at the time of accident
so as to insure the proper use of the air. The writer
would only add to this valuable suggestion that each
safety station should be reached by drill holes sunk from
the surface, a single hole for each station, of sufficient size
for passing food and water to the imprisoned men. The
supply of air should be sufficiently strong to drive back the
damp from entering the enclosed area. If the provision of
such refuge stations in fiery and dusty mines should prove
efficacious in a single instance in a decade of years it would
have earned its right to be considered always afterwards as
a necessary feature of such mines.

138. Record of Recent Disastrous Mine Explosions.
Some of the more disastrous explosions that have occurred
in this country during the past ten years are tabulated
here, because, to the best of the writer's knowledge, there
exists no authentic record of such catastrophes in America,
and because of the impressiveness of such a record, and
v/ith the hope that it may assist to stimulate efforts look-
ing to the adoption of remedial measures both in needed
legislation and mine management. In England and on
the Continent more attention has been given to the sub-
ject by the several governments of the states where the
work of mining is carried on ; and properly authorized com-
missions have been appointed at different times in England,
France, Belgium, and Austria to investigate the general
subject of mine explosions, and to determine, as far as may
be possible, by experiments performed on a large scale
and at great expense, the nature of the explosion of gas

MINE EXPLOSIONS

Table 22

189

LIST OF MINE. EXPLOSIONS OFFICIALLY REPORTED IN THE
UNITED STATES AND CANADA, NUMBERING 5 OR MORE
FATALITIES, SINCE JANUARY, 1896

Date

Place

Fatality

1896, Jan. 23

Newburg, W. Va.

March 23

Berwinsdale, Pa.

Oct. 29

So. Wilkes-Barre, Pa.

1897, Jan. 4

Alderson, Ind. T.

1898, Sept. 23

Brownsville, Pa.

1899, July 24

Grindstone, Pa.

Dec. 23

Sumner, Pa.

1900, March 6

Red Ash, W. Va.

May 1

Scofield, Utah

200

Nov. 2

Berry burg, W. Va.

1901, April 29

Alderson, Ind. T.

May 15

Chatham, W. Va.

Richland, Tenn.

June 10

Port Royal, Pa.

Oct. 26

Diamondville. Wyo.

Nov. 14

Pocahontas, W. Va.

(t H H

1902, Jan. 24

Lost Creek, la.

March 31

Dayton, Tenn.

May 19

Coal Creek (Fraterville), Tenn.

184

Fernie, B. C, Can.

127

July 10

Johnstown (RolHng Mill mine). Pa.

112

Sept. 16

Algona, W. Va.

Stafford, W. Va.

1903, April 13

Carbon, Ind. T.

Nov. 21

Ferguson, Pa.

1904, Jan. 25

Cheswick (Harwick mine), Pa.

178

March 6

Catsburg, Pa.
Tercio, Col.

Oct. 28

Nov. 29

Luke Fidler, Pa.

1905, Feb. 20

Virginia City, Ala.
Bluefield, W. Va.

116

March 18

Red Ash, W. Va.

Princeton, Ind.

April 3

Zeigler, 111.

Cabin Creek, W. Va.

Dubois, Pa.

Wilberton, Ind. T.

July 5

Vivian, W. Va.

Oct. 13

Frederickstown, Pa.

Nov. 4

Vivian, W. Va.

Bentleysville, Pa.

Dec. 1

Diamondville, Wyo.

1906, Jan. 4

Coaldale, W. Va.

Detroit, W. Va.

190

MINE GASES AND EXPLOSIONS
Table 22 — Continued

.Date

Place

Fatality

190B, Jan. 24

Witteville, Ind. T.

Feb. 8

Parral, W. Va.

Maitland, Col.

Piper, Ala.

March 22

Centurv, VV. Va.

April 21

iTinidad, Col.

June 6

Red Lod;:e, Mont.

July 19

Huger, W. Va.

Oct. 3

Pocahontas, W. Va.

Blossburgr, N. Mex.

Johnstown, Pa.

1907, Jan. 23

Primero, Col.

Fayette^■ille, W. Va.

Feb. 4

Elkins (Thomas mine), W, Va.

and dust separately and combined. It is to the work of
these commissions that we owe the most of our present
knowledge of explosive conditions in mines. Table 22
is a partial list of the fatal mine explosions that have
been officially reported since January 1, 1896, as causing
the deaths of at least 5 persons. That such a list shows
but a small portion of the actual fatalities and a still smaller
portion of the total number of explosions occurring is
evidenced plainly by the reports from any one of the states.
For example, in the Indian Territory alone, where a care-
ful record has been kept during the last ten years, the
reports of the U. S. Mine Inspector show that a total
of 174 explosions occurred, of which but 61 were fatal,
.causing the death of 117 persons. Of this large number of
catastrophes in a comparatively small mining district but
4 explosions, causing in all 30 deaths, appear in the table.
In this connection it is well to remember that the number of
fatalities is but an incident in the occurrence of an explo-
sion, the occurrence itself being the main fact, which may
or may not be accompanied with great fatality according

MINE EXPLOSIONS 191

as persons are or are not at hand. The fatality of an ex-
plosion depends further on the conditions of environment.

139. Prevention of Mine Explosions. — A strict enforce-
ment of the mining law of the state in which the mine is
located, and of the regulations in force at each mine,
together with a rigid discipline and eternal vigilance on
the part of officials and miners alike, will result in a de-
gree of immunity from these dread happenings in propor-
tion to the intelligence of all concerned, with respect to
the occurrence, behavior, and properties of mine gases.
This knowledge is as necessary to the making of proper
laws and regulations as it is to the safe performance of
the work in the mine. Though with the utmost of care
it may not be possible to obtain absolute freedom from
accidents of this nature, yet the evil can be greatly ameli-
orated by the careful and intelligent consideration of the
conditions in any particular mine with respect to the char-
acter of the coal, the gaseous condition of the seam, the
method to be adopted for the extraction of the coal, and
other like factors. The following general remarks will
serve to suggest precautionary measures that should be
considered in order to render the operations of mining
reasonably safe.

Care must always be taken to avoid the accumulation
of gas, by maintaining an ample and efficient circulation
throughout the workings. The air-current must be made
to sweep all cavities or other void places that form lodg-
ments for gas, and the velocity of the air must be sufficient
to effect the removal of the gas as fast as it issues. Aban-
doned areas left standing open may form dangerous
reservoirs of gas unless these are thoroughly ventilated
by an air-current made to pass constantly through them.
Often the best means of keeping such abandoned places

192 MINE GASES AND EXPLOSIONS

free from dangerous accumulations of gas is to sink one
or more 4-inch bore holes from the surface so as to tap
the gas at the highest point in this area. This has been
found to give immediate and permanent relief by draining
off all the gas that would otherwise accumulate in such
places and endanger the mines.

In the working of soft, inflammable coal every means
practicable should be adopted to reduce to a minimum
the breaking up of the coal and the formation of fine dust.
Where machines are used to mine the coal, and particu-
larly where coal is blasted, the accumulations of fine coal
and dust should be removed regularly from the roads
and from the working places. The watering or spraying
of the working face and the roads leading thereto pre-
vious to fu-ing a shot clears and cools the air and lessens
the quantity of dust that will be thrown into the air by
the force of the blast just in proportion to the thorough-
ness of the watering. To the same extent, also, is the
spraying of the mine haulways efficacious. Too much
reliance should not be placed on watering; there is no
ground for the belief that any practicable amount of
watering of the mine passages and workings will or can avail
to stop any mine explosion after it has once gained head-
way. Any system of watering practicable in a mine can
only lessen the tendency to an explosive condition of the
air by clearing the mine atmosphere and reducing to a
minimum the quantity of fine dust thrown on the air-
current by the operations of the mine. It is also possible
that the moist condition of a mine induced by injudicious
watering may even prove, under certain conditions, an
evil instead of a benefit.

Mr. James Ashworth, in commenting on the experiments
performed by Mr. Henry Hall, Inspector of Mines for the

MINE EXPLOSIONS 193

Liverpool district, England, draws attention to the fact
that some of the most violent explosions Mr. Hall obtained
occurred when rain had been falling nearly all the day,
and the air lacked but .6 grain of saturation, the tempera-
ture being 52° F. The moisture in the air was, therefore,
87 per cent, of the amount required for saturation. The
flame of the explosion in this case was projected 60 feet
into the air, above the top of the shaft. Mr. Ashworth,
who has given much thought to this subject, states
that the safest possible atmosphere for mine work
would be one that was absolutely dry; but, since this is
a practical impossibibility, he concludes that when the
conditions are such as to render blasting dangerous, a
working place should be made "soaking wet" before
firing, but elsewhere in the mine only suflticient water
should be used to clear the air of the fine dust raised
by the ordinary operations of the mine and borne in sus-
pension on the air-current. Briefly, the safest condition
with respect to fine inflammable dust held in suspension
in the mine air is not to be sought in abolishing the use
of water for the purposes of spraying, for this would not
insure the "absolutely dry" atmosphere that Mr. Ash-
worth advocates as the "safest atmosphere for mine work
and blasting." Indeed it is practically impossible to
realize such an atmosphere in the driest quarters of the
earth's surface, much less in underground workings.
Since, then, water must always be present in the mine
air to an extent that will make possible the explosion of
fine inflammable dust, relief and safety must be sought
in applying a sufficient quantity of water to clarify the air
traveling on the roads, and render it safer in presence of
gas, and more wholesome to breathe. The working face
in the vicinity of a blast should be made thoroughly wet

194 MINE GASES AND EXPLOSIONS

before firing a shot; the quantity of water used should
be in proportion to the fineness and inflammability of the
dust.

Under the dangerous conditions just described, the
most practicable plan for the spraying of a large mine
may be to run a pipe line the entire length of the haul-
ways from the shaft bottom to the heads of the several
entries. Arrangements should be made to reach the face
of each chamber or working place, either by means of
branch pipes of less diameter or by a suflacient length of
hose that can be attached to plugs in the main pipe on
the entry. At suitable intervals along the haul ways,
which should be determined by the conditions in the mine,
a jet spray or sprinkler should be attached permanently
to the main pipe and kept open continuously during work-
ing hours.

One of the most pernicious practices in the working of a
gassy seam, and a practice seemingly authorized by cus-
tom, born of the willingness of the miner to assume risk,
and of his thoughtlessness for himself and others, and in
part of his ignorance, is the practice of allowing the use
of mixed lights. From long and close observation it is
the writer's conviction that this seemingly guarded prac-
tice is responsible for mine disasters to a greater extent
than any other contributory cause. Under certain con-
ditions judged to be safe by the fire boss, and with the full '
knowledge of other mine officials, the miner, though fur-
nished with an approved form of safety lamp by the com-
pany, is permitted to take into the mine with him his own
common lamp, which he uses according to his own sweet
will, only to receive a sharp reprimand from the boss were
that individual to make an unexpected visit to his place
and find him thus. At another time, with the knowl-

MINE EXPLOSIONS 195

edge of the boss if not with his permission, the safety
lamp is hung on a convenient post near to the roof to
keep the miner informed (if he looks that way) of any
increase in the body of gas above him. Thus guarded
the miner with his open light set on the floor undermines
the face of coal and prepares a shot with an abandon of any
thought of danger that would be truly heroic if performed
for a noble purpose. Though a criminal offense under the
state law, the writer has seen men with a full knowledge
of the law and with reasonable intelligence but lack of
regard for their own safety or that of any one else in the
mine, pass a plain danger board marked ^'Gas" and pro-
ceed to work with their open lights within 10 yards of a
large body of firedamp, sufficient to have wrecked a good
portion or the whole of the mine. Such is the seemingly
approved recklessness of the average miner because of his
familiarity with danger.

The enactment of law and the punishment for viola-
tion of mine regulations are powerless to meet this
exigency; nothing but eternal vigilance on the part
of mine officials and an honest regard for the safety of
human lives can serve to avert the evil results of such
reckless disregard of danger.' As long as the use of mixed
lights is sanctioned by mine officials, there will continue
the same reckless disregard for the mine regulations on
the part of the miner, because he considers his judgment
equal to that of the fire boss, and is willing to take the
risk. But the unguarded raising of his lamp too near the
roof, or an unexpected agitation of the air, caused, it may
be, by a slight fall of slate or coal, ignites the gas, which
may result in a serious explosion. It is a foolish and dan-
gerous practice to light a thin layer of gas at the roof of
a well-ventilated chamber for the sport of seeing it burn

196 MINE GASES AND EXPLOSIONS

or for the purpose of getting rid of the gas. The quiet
burning of the gas may at any moment under the slightest
provocation develop into a serious explosion.

The use of electricity in any form or for any purpose
should not be tolerated in a gaseous mine. Under the
varied conditions of mining the risk of the ignition of fire-
damp by the sparking of wires or brushes, the burning
out of a fuse, or the breaking of a lamp, or other cause is
too great to be assumed by a responsible manage-
ment.

140. Relation of Blasting to Mine Explosions. — It wiK
not be denied that blasting in mines is a prolific cause of
the explosion of gas and dust in the workings. While this
is due in part to carelessness in the manner of firing the
shot, and in part to inexcusable ignorance in regard to
some of the simple principles of blasting, yet much of the
trouble must be attributed to a lack of knowledge, on the
part of the shot-firer, of the tremendous energies that are
locked up in the gas- and dust-laden air about him, even
exceeding by many times the energy of an equal weight
of the powder itself. For example, the energy of a single
pound of methane (marsh gas) mixed with air exceeds
that of a 25-pound keg of common black blasting powder,
while the energy of the same weight of carbon in the form
of fine dust is slightly more than half this amount. These
energies, expressed in foot- tons, have been given in Table 21.
It is then only a question of setting free the great ener-
gies that lie dormant in the stores of combustible matter on
every hand, in the mine, and the result is a mine explosion.
The wonder is that the action once started ever ceases,
the mine becoming a furnace in which the heat and the
pressure due to the combustion are largely confined. The
mine itself forms an immense cul de sac that greatly

MINE EXPLOSIONS 197

intensifies the results, till the lack of oxygen alone puts
an end to the chemical activities.

When a shot blows its tamping instead of breaking down
the coal, a portion of the energy of the charge is expended
on the air. A sheet of flame is projected with much force
from the hole, producing a great commotion in the air and
raising a cloud of fine dust, which is at once converted into
gas and expands with explosive force. Under certain con-
ditions in narrow and contracted workings the action is
accumulative and what takes place on a small scale in
such a chamber or heading is duplicated on a far greater
scale through the mine, in a mine explosion. The point
to be remembered is that the heat and the pressure incident
to blasting in a confined or contracted chamber or heading
may easily reach the danger point when the temperature
of the air in the immediate vicinity of the shot will be suf-
ficient to start fresh chemical activities. The danger is much
increased by the presence of fine dust floating in the air,
and is not wholly dependent on the inflammability of the
dust (Art. 134), though greatly augmented thereby. The
presence of even the smallest quantity of gas in the air
other than the gases produced by the explosion of the
powder adds to the danger of the ignition of the dust if
the latter is combustible.

A blown-out shot furnishes the necessary volume and
intensity of flame required for the ignition of gas and dust,
or even of dust alone in the entire absence of gas except
such as is produced by the burning of the powder, provided
the dust is combustible. The danger arising from fine
incombustible dust floating in the air can only exist when
gas is present. The influence of such dust in assisting the
explosion of gaseous mixtures has been explained as being
due to what Berzelius has called catalysis, or decomposi-

198 MINE GASES AND EXPLOSIONS

tion by contact. There is yet much to be learned in regard
to this action of fine incombustible dust, but little doubt
exists cf its influence being to increase the danger of igni-
tion in a gaseous atmosphere.

A windy shot differs essentially from a blown-out shot,
which does not break down the coal, but simply blows
out the tamping. A windy shot, while it performs the
work intended, expends a portion of its energy on the
air, because the charge was in excess of what was re-
quired to break the coal; the shot was miscalculated.
A similar effect is also produced sometimes when two shots
are fired in rapid succession in a close place where the air
is to a certain extent confined. Neither of the shots
probably, if fired alone, would have caused any trouble;
but fired in rapid succession the flame of the second shot
is projected into an already overheated and overcharged
atmosphere, laden with a considerable percentage of com-
bustible gas and dust — the result of the first shot. As a
consequence a local explosion takes place, which produces
at least a heavy concussion of the air in the adjoining
workings.

, It is a dangerous practice to lay two shots that
$,Te intended to be fired at the same time, so that they
will face each other more or less directly or shoot across
each other; and there is some danger, which may often
be avoided, in laying a shot so as to face a strong air--
current in an airway. The heat energy developed at the
nioment of explosion is greatly augmented by the momen-^
tary arrrest of a ton or more of air traveling at a velocity
of J say 600 feet per minute, representing practically 600
foot-tons, or say 1,500 B.T.U., in addition to the necessary
he^t of the charge. The heat energy of 1 pound of ordinary
black blasting powder (Table 21) is 360 -loot-tons, and fofc

MINE EXPLOSIONS 199

a normal charge of, say 6 pounds of this powder, the heat
energy would be 6x360 = 2,160 foot- tons, or say 5,500
B.T.U. In such a case the effect of shooting against the
air in this airway, in blowing down roof or lifting bottom,
would be to increase the heat energy imparted to the air
at the moment of the explosion more than 25 per cent.

Many attempts have been made and much labor and
money expended to discover an explosive that would be
safe to employ in gaseous mines. It is commonly agreed
that while the different grades of black blasting powder,
owing to the gradual development of the full explosive
force, are best adapted to breaking down the coal in suit-
able shape for loading, yet the flame that always accom-
panies the explosion of this powder renders it an unsafe
explosive to be used in the presence of gas. In seeking
to minimize or wholly overcome this evil, if possible, re-
course was had to different methods. Certain inert sub-
stances were introduced into the composition of the
powder, such as sulphate of magnesia, the carbonates of
sodium and calcium, to reduce the activity and absorb
heat from the gaseous products of the explosion. Another
method was to introduce nitrates into the composition of
the powder to such an extent as to render the gaseous
products of the explosion as nearly as possible incombus-
tible. These highly nitrated powders are the famous
Sprengle or so-called flameless powders. No powder,
however^ is absolutely without flame. Another method
tried was to surround the explosive charge with water;
this was known as the water cartridge, and was found by
the experiments of the Accidents in Mines Commission
(1881) to greatly reduce the risks of shot-firing in the
presence of gas. In other experiments by the same com-
mission wrought iron cylinders of the diameter of the bore

200

MINE GASES AND EXPLOSIONS

hole and containing condensed (liquefied) carbon dioxide
were placed over the charge in the hole for the purpose of
extinguishing the flame of the blast by the liberation of
carbon dioxide gas in large quantity. These methods,
however, while they reduced the risks, offered no certain
immunity from the danger due to the flame of the ex-
plosion.

In the following table are given the computed maximum
temperatures resulting from the explosion of some of the
more conmion explosives used in blasting. These tem-
peratures are given here as suggestive of possible condi-
tions with respect to the use of these explosives in mine
work and for the sake of comparison.

Table 23
computed and estimated temperatures of explosion of

VARIOUS EXPLOSIVES

Explosive

Computed Temperature
of Explosion,
Deg. (Fahr.)

Estimated Tempera-
ture of Explosion,
Deg. (Fahr.)

Gunpowder ....

6,100

4,400 (average)

9,900

6,768

4,000

3,000 to 3,600

5,700

5,745

Black blasting powder

Nitroglycerin

Guncotton

Blasting gelatine

5,828
5,260

Dynamite

Tonite

4,798
3,812

Roburite

Carbonite

3,352

The detonating explosives, as dynamite, guncotton, blast-
ing gelatine, carbonite, gelignite, and others having nitro-
glycerin for a base, or ammonite, roburite, etc., having
ammonium nitrate for a base, or the picric acid compounds,
as lyddite, melenite, etc., all possess such a rapid and
powerful action that the high temperature common to the
explosion of powder is, in their case, maintained but for

MINE EXPLOSIONS 201

a slight fraction of a second, a time far too small for the
ignition of pure firedamp (Art. 127). Unfortunately, how-
ever, firedamp as found in the mine is rarely if ever pure,
being mixed in varying proportions with other hydrocarbon
gases, sulphureted hydrogen, or olefiant gas, or contami-
nated with the fine floating dust of a highly inflammable
coal, all of which lower the ignition point of the mixture.
There is besides, in the explosion of some powders, a
shower of projected, incandescent particles of combustible
matter, coming mostly from the coal powdered by the force
of the explosion, but in part from the powder itself.
The heat of these burning particles is of sufficient inten-
sity and duration to ignite any firedamp present.

The risks incident to blasting in the presence of gas
are reduced to a minimum only when every possible pre-
caution is taken to prevent the ignition of the gas that in
some cases maintains a constant flow and cannot be suffi-
ciently diluted with air, at the face of a breast, to prevent
its ignition. The ventilation of such a breast must be
arranged so that an accumulation of gas cannot occur as
long as the current is maintained, which will insure the
workings against an explosion, should the gas be ignited
at the face, by the flame of a blast or otherwise. The
means adopted for tamping and firing the charge and the
method of lighting the same is of much importance in this
connection. Electric firing must always present a far
greater degree of security than firing by fuse or squib,
and the latter should never be considered under the con-
ditions named. An approved form of touchpaper — a
paper that has been treated with a weak solution of salt-
peter and dried, should be employed to ignite the fuse,
which when used should be the best quality of double-tape
fuse. The method of igniting the fuse by a fine wire heated

202 MINE GASES AND EXPLOSIONS

to redness by inserting it through the meshes of the gauze
of a safety lamp is dangerous, both as being liable to injure
the gauze, and to ignite the gas by its own heat. The wire
is, of course, small and does not retain its heat long, but
its temperature ranges from about 1,000° F. when it first
begins to glow red in the dark, to 2,370° F. at a white
heat; the temperature of the wire at a dull-red heat is
1,290° F., which is above the ignition point of pure fire-
damp (1,200° F.). A charge should never be tamped
with any combustible material; sand or the powdered
clay taken from the roads and moistened makes a good
tamping. A small ball of clay should be carefully pushed
home over the charge first and the stemming or tamp-
ing rammed harder as the hole is filled. The prac-
tice of using powdered coal or slack for stemming is
dangerous.

The firing of shots in a mine should begin on the last
or the end of the air and proceed toward the intake, so that
the gases produced by the first shots fired will be carried
away from the vicinity of later shots. By this means
not only do the shot-firers work in pure air, but the risk
is avoided of the heated and combustible gases produced
increasing the explosive condition of the air passing the
face where shots are being fired. The air at the face dur-
ing firing time should be pure and its temperature normal,
that is to say, neither cool nor hot, since both of these con-
ditions increase the danger. A large volume of pure air
traveling at a moderately low velocity is the ideal con-
dition that should prevail throughout the workings during
and immediately preceding the time for firing, whether or
not gas is generated in the mine.

The slowing of the fan or in any manner reducing the
circulation at or just previous to the time of firing is a dan-

MINE EXPLOSIONS 203

gerous practice. The Mine Inspectors' Reports for Iowa *
give two instances of fatal explosions that occurred where
this practice was in vogue. In the latter case the report
reads: ''The ventilation in the 5th and 6th south entries
was generally good, but as at the request of the shot-
firers the fan was stopped when the miners were leaving
the mine, there was little if any air moving at firing time."
The argument used in support of this practice is briefly
as follows: — A large volume of air means an increased
supply of oxygen, which is the necessary fuel for an ex-
plosion, should one be started by the flame of a windy or
a blown-out shot. — Granting this for a moment, is it not
true that the reduction of the air-current at firing time
permits the accumulation in the mine air of an even more
dangerous fuel in the form of an increased percentage of
carbon monoxide produced by the explosion of the powder,
which with the fine dust blown into the air rapidly in-
creases the explosive condition of the air? The air-
current in its weakened condition and staggered by each
succeeding blast is no longer able to oppose the expansion
of the gas- and dust-laden air, which is forced back into the
adjoining breasts and chambers where shots are yet to
be fired. Could anything be more dangerous? Would any
practical mining man hesitate for an instant in the choice
between such an atmosphere of heated, dust-laden, and
combustible gases and the pure air of a moderate intake
current having a normal temperature? The argument
for reducing the air at firing time is not strengthened by
the statement that a dust explosion always advances and
feeds on the intake air. It could do no otherwise than to

* Tenth Biennial Report of the State Mine Inspectors, Iowa, page
54. Twelfth Biennial Report of the State Mine Inspectors, Iowa,
page 23.

204 MINE GASES AND EXPLOSIONS

feed outwards, since the narrow confines of the inner work-
ings are quickly stopped to the passage of flame by the
products of tne combustion. Let this practice cease, that
no more fives be sacrificed to a foofish misconception of
mining conditions.

141. Relation of Atmospheric Conditions to Mine Ex-
plosions.— The atmospheric conditions that affect or are
commonly supposed to affect the occurrence of mine
explosions are those relating to the pressure, temperature,
and hygrometric condition of the atmosphere. The ear-
nest desire of many investigators and practical observers
to safeguard the work of mining by every possible means
that science could suggest has no doubt led some to over-
estimate the effect not only of atmospheric conditions, but
of all the causes suggested as in any way contributing to
produce an explosive condition of the mine air. The true
significance of barometric changes in relation to the occur-
rence of mine explosions has been much misunderstood,
owing chiefly to the unguarded statements of some writers.
The misapprehension thus caused in the minds of men
charged with the conduct of mining operations has led too
often to an utter disregard for the barometer and its in-
dications.

The effect of a sudden fall of barometric pressure varying,
say from one-half to one inch in from 6 to 12 hours is
quite generally conceded to be followed, or it may be
accompanied, by an outflow of gas from all standing areas
and abandoned places in mines; there is also naturally
an increase of gas on the falls and in proximity to large
faults. Gas that has accumulated above a roof slate is
likewise affected, and doubtless in many such cases the im-
mediate result is the removal of from 50 to 75 pounds of
support per square foot from beneath, which in effect adds

MINE EXPLOSIONS 205

this amount to the weight of the slate and invites falls of
roof in the old workings, thus increasing the amount of gas
set free. Some assert that there is besides an increased
transpiration of gas from the solid face of the coal due to
the decreased atmospheric pressure, but the rate of trans-
piration is not appreciably affected by. any possible fall of
the barometer, since the pressures imder which gases are
occluded, which is estimated by eminent authority to be
as high as 3,000 pounds per square inch, are too great, as
compared with atmospheric pressure, to be affected appre-
ciably by such changes.

As Mr. A. R. Sawyer has remarked, and the statement is
warmly supported by Sir Frederick Abel, — It is idle to
attempt to establish or prove that there is or has been any
fixed relation between such barometric changes and the oc-
currence of mine explosions. Two reasons show at once the
futility of such attempts : First, in all well regulated mines
the slightly increased outflow of gas at such times will be
amply provided for by an efficient system of ventilation,
and the ignition of the gas avoided by preventing its
accumulation and by other precautions and strict regula-
tions enforced by the vigilance of the bosses. Second, a
large number of mine, explosions, both gas and dust ex-
plosions, are plainly due to causes that are independent and
have no connection with any special outflow of gas into the
workings. Thus, while the importance of daily and hourly
observing the barometer in connection with all large min-
ing operations is clearly established, it does not follow that
a sudden fall of barometric pressure is signahzed by the
occurrence of one or more explosions or vice versa. It is
even claimed by some authorities that periods of high
barometric pressure appear from pubfished *' colliery
warnings" to be the more dangerous for no other reason

206 MINE GASES AND EXPLOSIONS

than because men are less careful at such times than
when the barometer is low or falling.

The temperature and hygrometric condition of the air are
go closely associated that the consideration of the one in-
cludes that of the other. There has been much confusion
of ideas in regard to the supposed influence of each of
these conditions in producing an explosion of gas or dust
in mines, and much that has been written in this respect
will hardly stand the test of a scientific analysis. A full
understanding of this important subject involves much
that is yet unknown, which fact alone suggests caution.
There is the gravest danger in speculation such as that
to which reference has already been made, namely, the
pernicious practice of reducing the circulation of air in a
mine at the time of firing, in order, as it is claimed, to
reduce the quantity of available oxygen expecting thereby
to reduce the explosive condition of the mine air.

It is pure speculation at present to assert that a
saturated condition of the mine air, other things being
equal, will reduce its explosive condition to a minimum.
This has not been proved, but rather disproved by experi-
ment (Art. 139) and by explosions that have taken place
in very wet mines. The attempt to show that the colder
seasons of the year are more productive of mine explo-
sions, or that these are attributable to a reduced tem-
perature of the air, has proven almost as futile as the en-
deavor to show a connection between such explosions
and barometric changes, to which reference has been made.

All of these atmospheric influences are operative and
each contributes its share towards creating an explosive
condition of the mine air, but often in a different way
from that supposed. The cold air of winter entering the
mine carries with it, at the best, but a comparatively

MINE EXPLOSIONS 207

small amount of moisture even if saturated. The tem-
perature of this air being raised by the natural heat of
the mine, its capacity for absorbing heat is greatly in-
creased, even exceeding that of ordinarily dry air in
summer. The effect of this is twofold — the moisture is
taken from the coal dust, which is thus rendered dry and
its inflammability increased, and this moisture abstracted
from the dust is added to the air, making it better suited
to the purposes of combustion.

To overcome the danger due to a cold air-current enter-
ing the mine and having its capacity to absorb moisture
raised by the natural heat of the mine, it is a good plan
to use the exhaust steam of the pumps, if possible, to
heat the intake air and saturate the same at a point near
the foot of the shaft, so that the air will pass into the work-
ings at a normal temperature and practically saturated.
It is common for the air-current in a mine to pick up the
moisture of the mine in certain portions of the workings
and deposit it at other points, and this process may be
repeated several times before the upcast is finally reached.
The weight of water in the form of vapor carried up the
shaft by the air-current of a large mine, each minute, far
exceeds the general expectation. A current of 120,000
cubic feet per minute, returning from the mine in a satu-
rated state at a temperature of 60° F., carries up the shaft
1 ton of water every 20 minutes, or 3 tons per hour. A
current of 150,000 cubic feet per minute carries practically
15 gallons, or nearly one-half barrel of water up the shaft
per minute under the same conditions. A current of
175,000 cubic feet per minute would deposit, as is often
the case (Art. 83), in the fan drift at the top of the shaft,
practically one-half gallon per minute for each degree of
fall in temperature, or 5 gallons per minute for a drop of

208 MINE GASES AND EXPLOSIONS

10 degrees from 60° to 50° F., creating thereby a heavy
downpour resembling a driving rain.

142. Earth Breathings. — The observations and experi-
ences of mining men are every day making the fact more
clear, that subterranean influences are very largely re-
sponsible for the spasmodic ebb and flow of gas in the
strata, giving rise to irregular periods of frequency of mine
explosions. It has been observed for some time that
mine explosions occur very often in groups, and that
between these periods or groups of explosions there will
be irregular periods, during which few explosions will take
place. It is not surprising to observe that there is often
a seeming contemporaneity, not to say connection, be-
tween periods of volcanic activity and the periods of
frequency of mine explosions.

In considering a mine explosion there is a general will-
ingness, not to say tendency, to consider the gaseous con-
dition of the workings in any given case as varying only
with the physical conditions in the mine, by which is
meant those conditions relating to the number of feeders
active, extent of faults, area of abandoned workings stand-
ing, frequency of roof falls, etc. Sufficient attention has
not been given to the variation of pressure of gas that
may occur at irregular intervals in the strata. This varia-
tion of pressure has its origin within the earth, and results
in a more or less spasmodic outflow or emission of gas
from the strata, which may be appropriately called earth
breathings.

The direct result of irregular earth breathings is a
corresponding fluctuation in the gaseous condition of
all underground workings. This theory, if true, would
give rise to periods of frequency of mine explosions, assum-
ing that an increased outflow of gas brings an increased

MINE EXPLOSIONS 209

ability of explosion. It is clear, however, that explosions
may occur at times when the outflow of gas from the strata
is less, and may not occur in the proper periods when the
emission of gas is stronger, but these would not neces-
sarily argue against the theory of periods of danger in
mines. At the most, such errant explosions would only
prove that periods of danger in mines are not always
periods of frequency of mine explosions. During such
periods of danger mine officials and miners should exercise
greater care and vigilance, and should employ every pre-
caution to insure safety.

Such a period of frequency would seem to have occurred
in 1902, when within less than three months 550 lives were
lost in four mine explosions and the terrible eruption of
Mt. Pelee occurred, beside a number of other small ex-
plosions. It is well to remember that the fatality of the
occurrence does not mark its importance in this regard.
Few or many may be killed or no fatalities may result,
according to the presence of men in the vicinity and the
conditions that determine the violence and the extent of
the occurrence. The chief occurrences of the 1902-period
were the following:

Lives
May 19, Frayterville mine explosion. Coal Creek,

Tenn 184

20, Mt. Pelee eruption, Martinique, West

Indies 28,000

23, Coal Creek mine explosion, Fernie, B. C,

Canada 127

July 10, Rolling Mill mine explosion, Johnstown,

Pa 112

Aug. 1, Mt. Kembla mine explosion, Wallangong,

N. S. W 127

210 MINE GASES AND EXPLOSIONS

Then followed a period of quiet, the year 1903 being
marked by few explosions; but this period of calm was
rudely broken by the terrible disaster in the Harwick
mine, at Cheswick, Pa., January 25, 1904, costing 178
lives. The frequency of these occurrences steadily in-
creased. The year 1905 was marked by much unrest,
and in the United States alone over 300 lives were sacri-
ficed in thirteen mine explosions (Table 22). The climax
was, however, reached in the early part of the following
year, and this may rightly be called the 1906-07 period.
The chief occurrences of this period, made memorable by
their terrible results, are as follows :

Lives
Jan. 4 to Feb. 19, five mine explosions. United States. 97
Feb. 21, Earthquake and tidal wave, Colombia,

S. A 2,000

Rpported activity of Mt. Pelee, Martinique,
W. I. "^

27, Cahaba No. 2 mine explosion. Piper, Ala ... 9
Mar. 10, Courrieres mine explosion, Pas-de-Calais,

France.. 1,200

17, Earthquake, Island of Formosa, Japan; esti-
mated $45,000,000 property loss, and
thousands of lives.
22, Century mine explosion. Century, W. Va. . . 21

28, Takashima mine explosion. Island of Taka-

shima, Kinshu, Japan 307

Apr. 3, Mt . Vesuvius eruption began, lasting 14 days ;
several towns destroyed and hundreds of
lives.
7, Earthquake, Island of Formosa, Japan, town
of Kagi wholly destroyed and 109 lives
lost.

MINE EXPLOSIONS 211

Lives
Apr. 18, Earthquake, San Francisco, Cal., $300,000,-
000 property loss and estimated 2,000
lives.

20, Earthquake shocks, Calumet, Mich., and

Honolulu; fatal.

21, Mine explosion, 40 miles west of Trinidad,

Col 22

Mt. Hecla, 5,108 feet high, southwest coast

of Iceland, reported active.
Volcano, 9,000 feet high, north coast Las
Palmas, Canary Island, active.

The late summer of 1906 was marked by continued
unrest. The memorable earthquake of August 16,
destroying property valued at $250,000,000 in Valpa-
raiso; the severe shocks in Porto Rico, September 27,
and the great earthquake recorded as having occurred
in the bed of the Indian Ocean, October 1, were followed
by mine explosions at Pocahontas, Va., October 3, loss

37 lives; Blossburg, N. Mex., October 5, loss 15 lives;
Durham Colliery, Wingate, England, October 15, loss 25
lives; Johnstown, Pa., October 24, loss 7 lives.

From October 6 to 10 Mt. Pelee again threw out
clouds of ashes, terminating with a violent eruption on
October 11. That this notable period of disturbance has
not ended yet is shown by the Kingston, Jamaica, earth-
quake, first shock January 14; Primero, Col, mine explo-
sion, 20 lives, January 23; Kingston, second shock, Janu-
ary 28, and the same date two mine explosions, Essen,
Germany, 275 lives, and Lille, France, 20 lives; the day
following, January 29, Stuart mine, Fayetteville, W. Va.,
75 lives; and February 4, Thomas mine, Elkins, W. Va.,

38 lives.

212 MINE GASES AND EXPLOSIONS

Such records point strongly to the possible and indeed
probable connection between seismic disturbances and
periods of danger in mines, if not to periods of frequency
of mine explosions, the latter in fact being a possible in-
cident of the former. A study of these facts cannot but
be suggestive in respect to the need of exercising greater
care at such times in the conduct of all mining opera-
tions, and adopting every expedient tending to reduce
the explosive condition of a mine. Particular attention
should be given to the study of these facts, with respect
to their bearing on the working of soft inflammable coals,
especially when lying in thin seams, necessitating restricted
airways and passageways.

143. Calculation of Initial Pressure of a Gas Explosion. —
At the moment of explosion the expansive force of the
gaseous products is determined by their relative volume
and temperature, referred to the original pressure and
volume of the gases exploded. The first step is to deter-
mine whether there is any change of volume before and
after explosion. In order to do this the equation express-
ing the reaction that takes place when the explosion
occurs must be written. The reaction that takes place
in the complete explosion of pure methane or marsh gas
(Art. 42) is expressed by the following equation :

Before Explosion After Explosion

CH4 +2O2 +8N2 =C02 +2H2O +8N2
Molecular volumes 12 8 12 8

In this case, which represents the explosion of a body of
pure methane in air, there is no change in volume due to
the reaction, since the sum of the molecular volumes of the
gases is the same after as before the explosion took place.
Hence the explosive force must be calculated for the in-

MINE EXPLOSIONS 213

crease of pressure due to the temperature resulting from the
reaction, which was found (Art. 69) to be 460+5,840 =
6,300° F., absolute temperature. Assuming a normal tem-
perature in the mine previous to the explosion, say
60°, or 520° F., absolute temperature; and assuming an
original pressure of 14.7 pounds per square inch (sea
level), and calling the required pressure x, we have (Art.
62)

^ 6,300 , ,, ^ 6,300 ,^^, „

147 "" 520"' a; = 14.7 X-^ =1^^*1 ^^' P^^ ^^' ^^'

In the explosion of carbon monoxide in air there is a
change of volume due to the reaction, and seven volumes
before the explosion are reduced to six volumes after,
which results in a corresponding reduction of pressure.
The reaction that takes place, together with the molecular
weights, and the relative weights and volumes of the
several gases concerned in the reaction and the gaseous
products are as follows:

Before Explosion After Explosion

2C0 +O2 +4N2 =2C02 +4N2

Molecular weights 56 32 112 88 112

Relative weights 1 ^ 2 If 2

Relative volumes 2 14 2 4

The volume being reduced chemically and the gaseous
products expanding to the original volume makes the
volume ratio affecting the pressure 7:6 instead of 6:7.

To find the temperature due to the explosion the relative
weight of each of the gaseous products is multipHed by its
specific heat (Tabic 4), and the sum of the heats thus
obtained gives the heat required to raise the temperature
of the products of the combustion 1° F. (Art. 69).

214 MINE GASES AND EXPLOSIONS

Thus, CO2 .1539x14- = .2418 B.T.U.
N2 .1735x2 =.3470 B.T.U.

Total .5888 B.T.U. required per 1° F. rise.

But these products are obtained from the combustion
of one pound of carbon monoxide, which is the relative
weight of that gas used in the above equation. Now the total
heat produced by burning one pound of carbon monoxide to
carbon dioxide is (Table 5) 4,325 B.T.U. Hence the total

4 325
rise in temperature produced by this reaction is InoQ^

.0000

7,345° F.; and the resulting temperature is, assuming
60° F. as the original temperature of the gases, 7,345 +60 =
7,405° F., or 460 +7,405 =7,865° F., absolute temperature.
Finally, calling the required pressure x, and writing the
pressure ratio equal to the inverse volume ratio (Art. 63)
multiplied by the absolute temperature ratio (Art. 62),
since each of these laws acts independently of the other,

X 6 /7,865\
14.7~7V520 /'

and

a;=14.7Xy ( -ToQ-) =190.5 lb. per sq. in.

The effect of the heat developed chemically by the reduc-
tion of volume, in this case, and which acts adiabatically
to expand the gases, is shown by the use of equation 9
(Art. 48); thus,

/ \-83/7,865\
a: = 14.7(-) (-520 / ^^^^-^ ^^- P^^ ^^- ^^•

The chemical heat thus increases the pressure in this
case about five pounds.

CHAPTER VI
SAFETY LAMPS

144. Early Practices. — ^The history of the lighting of
mine workings dates back to the early part of the eigh-
teenth century when small candles (tallow dips) were used.
These were set or held in a lump of wet clay. When look-
ing for gas the flame of the candle was reduced to a mere
glimmer by surrounding the wick below the flame by
clay. The candle was then very cautiously raised from
the floor toward the roof, the observer screening the brighter
portion of the flame with his hand and watching for the
first appearance of the pale blue cap above the flame,
which was then known to indicate the presence of gas.
When this appeared the candle was lowered quietly and
its flame extinguished before attempting to drive out
the gas. A common and dangerous practice at that time
was to get rid of the gas by firing it; this was done by a
person selected for his nerve rather than his caution.
Dressed in a suit of sackcloth or leather dampened, this
man, who was well named a ''fireman," would lie prone
on the floor of the passage and light the gas above
him by raising his candle fastened to the end of a long
stick. If he survived, which was not always the case,
he would withdraw promptly to fresh air after the flame
had passed over him.

Another practice in deaHng with gas, and one which
until quite recently has been in vogue in some Belgian

215

216 MINE GASES AND EXPLOSIONS

mines, is that of keeping lamps constantly burning in
certain cavities of the roof where the gas would other-
wise accumulate. These were the so-called eternal lamps,
and their purpose was to burn the gas as fast as it came
from the strata. The sad results of these and other dan-
gerous practices aroused a deep interest in the subject,
and many attempts were made to provide a means of
safely lighting underground workings. Various phosphor-
escent substances, such as the putrefying skins of fish,
were carried into the mine, where they were hung up near
the working face only to make the darkness visible.

145. The Steel Mill.— About 1750 Carlisle Spedding, a
promising young miner of Cumberland, England, not only
improved the method of ventilation in mines by coursing
the air, but invented the "steel mill" for giving light.
This mill, as shown in Fig. 17, consisted of a thin disk of

Fig. 17.— The Spedding Steel Mill

steel, so mounted in an iron frame that it could be rotated
at a rapid rate by means of a spur-gear and hand-crank.
A piece of flint held against the rim of the rapidly moving
wheel caused a bright shower of sparks, which gave con-
siderable light as long as it lasted. A boy was employed
to turn the mill. Young Spedding had been selected to

SAFETY LAMPS

217

take charge of the Whitehaven colheries at Cumberland,
and had been sent by the owner of the colheries to New-
castle-upon-Tyne to learn more of coal mining. While
there he was severely burned by an explosion of firedamp.
Five years after the invention of his steel mill, in 1755,
he was killed in an* explosion of gas at the Whitehaven
colheries. The use of both the candle and the steel mill
continued — although they were at times the undoubted
cause of numerous explosions — till the invention of the
safety lamp early in the nineteenth century.

146. The First Mine Safety Lamp. — The honor of con-
structing the first safety lamp that was ever used in a
mine rightly belongs to Dr. William
Reid Clanny, F.R.S., Sunderland,
England, who described and pre-
sented to the Royal Society of Arts
his first lamp, May 20, 1813. This
lamp was first used, in the slightly
modified form shown in Fig. 18, in
the Herring Mill Colhery, October 16,
1815, more than two years later. As
then used the lamp consisted of a
metallic case a, made air tight
and fitted with a semicircular glass
front, as shown. Within the case
was a candle, the air necessary for
its combustion being admitted or
rather forced into the case through
a water seal in the bottom by means
of the bellows b and the tube c. The products of the com-
bustion, escaping through the narrow opening at the top
of the conical tube or cap d, prevented the passage of
flame out at that point. The flame of this lamp was

Fig. 18

The First Safety Lamp—

Dr. Clanny

218 MINE GASES AND EXPLOSIONS

therefore completely isolated from the outer atmosphere,
but the constant attention necessary to keep the lamp
supphed with fresh air prevented its general adoption
in the mine. The lamp was much superior as a means
of lighting to the steel mill but inferior to either the
Stephenson or the Davy lamp, both of which were intro-
duced a few months later.

147. What Constitutes a Safety Lamp.^ — All safety lamps
of the present day consist essentially of an ordinary wick-
er gas-fed flame inclosed in a combustion chamber^ all
the openings to which, for the admission of air or the es-
cape of gases, are carefully protected by wire gauze, or
consist themselves of long narrow tubes through which
no flame can pass. A safety lamp affords protection
only so long as certain conditions regarding its use are
fulfilled. These conditions will be described later.

148. The Principle of the Safety Lamp. — The principle
on which all safety lamps depend to a greater or less degree
is threefold; and as if decreed by fate these three joint
principles, each equally important in its relation to the
protection and security sought, form respectively the chief
characteristics of the original Clanny, Davy, and Stephen-
son lamps. These lamps may be truly said to have repre-
sented in their simplicity the three essential elements
in safety-lamp construction as understood today. Dr.
Clanny was certainly the pioneer, and demonstrated in his
original lamp. May 20, 1813, the first great principle of all
safety lamps, namely, providing an inclosed space or
combustion chamber in which to place the light-giving flame.
The means adopted by Dr. Clanny, however, for supply-
ing air to the chamber and preventing the passing out
of the flame were wholly impracticable for use in the
mine, and it remained for Sir Humphry Davy to discover

SAFETY LAMPS 219

and proclaim to the world, December 15, 1815, the won-
derful property of wire gauze, which under certain con-
ditions would permit the free passage of air through its
mesh, while it presented a solid wall to the flame.

Great as was the work so far performed, it would still
be incomplete without the additional element of protection
that George Stephenson sought to utilize in his first lamps.
Mr. Stephenson's theory was ^^If a lamp could be made
to retain some burnt air above the flame and permit the
firedamp to come in below in small quantity, to be con-
sumed as it came in, the burnt air would prevent the pass-
ing of flame upwards, and the velocity of the current below
would prevent its passing downwards." Stephenson's first
lamp, tried at the Killingworth Colliery, October 21, 1815,
failed to burn satisfactorily; some alterations were made
in the lamp and a second trial was made at the same
blower, November 9, with slight improvement. The
lamp was then reconstructed on different lines and was
found on trial, November 28, 1815, at the Killingworth
blower, to bum with satisfaction and to be "perfectly
safe.''

The threefold principle of all safety lamps may then be
briefly stated as follows: Inclosing the lamp flame in a
case forming a combustion chamber (Clanny); Extinction
of flame by the cooling effect of wire gauze (Davy) ; Extinc-
tion of flame by confining the burnt air in the upper portion
of the lamp (Stephenson).

149. Safety-lamp Construction. — A few points stated
briefly here in reference to the material used and the
fitting of the parts and their correlation will be helpful.

The material used is mostly brass, aluminum, copper, and
iron. Oil vessels are either brass or aluminum; gauzes are
iron or copper; the lamp standards are brass or h'on;

220 MINE GASES AND EXPLOSIONS

hoods brass or ahiminum, and bonnets sheet iron, brass,
or aluminum. Aluminum, while adding a trifle to the cost
of a lamp, owing to its not being as workable as brass,
possesses certain advantages that have caused it to be
used in many lamps. The metal is less than three-tenths
the weight of brass, and about one-third the weight of
wrought iron, which greatly reduces the weight of a lamp
made of this material. It is not as readily corroded by
water containing sulphuric acid as is iron or even brass.
Although its specific heat (.2143) is higher than that of any
other metal used in lamp construction, yet, owing to its
lightness, aluminum heats quicker than either brass or iron.
Brass is quite generally preferred to aluminum for lamps,
chiefly for the reason that it takes a higher polish and is
more easily kept clean.

Copper gauzes are sometimes preferred to those made of
iron wire^ because the copper is more durable and does
not burn out or corrode as rapidly as the iron. On the
other hand, copper (sp. heat =.0951, sp. gr. 8.9) heats more
rapidly than iron (sp. heat =.1138, sp. gr. 7.7), and will
therefore pass flame slightly quicker; besides, a copper gauze
is not a good gauze for a Davy lamp when testing for gas,
because of the strong reflection from the copper wires,
which obscures the flame cap.

The fittings of a safety lamp must be well made with
tight joints. The seams of gauze are lapped, folded, and
hammered flat, except in special cases, where they are
sewed with wire. Fig. 19 shows in sectional detail the
manner of joining the gauze g to the base ring c by means
of the screw collar r, which may fit the same thread as the
oil vessel v. The standards s are screwed into the base
ring c. The wick tube w is provided with a flange /, by
which it is held in place by the screw nipple n. The

SAFETY LAMPS

221

pricker p passes up through a small brass tube brazed
into the oil vessel. This describes in a general way only
the relation of these parts; there are, however, many
different forms of construction, in which the several parts
are fitted together in various ways. All safety lamps are

Fig. 19. — Showing Attachment of Gauze to Lamp and General
Arrangement of Parts

constructed on the same general principles that formed
the chief features of the three lamps previously mentioned.
Dr. Clanny's first lamp was of course only useful as
demonstrating the first great principle of all such lamps.
The Davy and Stephenson lamps were in some respects
rival lamps, but it became necessary for Stephenson to
appropriate the Davy gauze to improve his lamp and
make it more practical for mining use.
No one can read the accounts of the controversy that

222 MINE GASES AND EXPLOSIONS

arose, more between the friends of these two rivals than
between the men themselves, without feeling impressed
with the honest right of each claimant to his due share
of the results, which must be considered as jointly opera-
tive to some extent in all lamps today. While it is true
that Sir Humphry Davy, an educated chemist, un-
doubtedly approached and solved the problem on a more
intelligent basis than did George Stephenson, a practical
mechanic, educated in a night school by devoting his
spare hours to study, yet the fact remains that as every
lamp gauze today bears evidence to Davy's scientific skill,
so every bonnet and hood protecting the discharge area
of a lamp is a silent reminder of Stephenson's practical
insight and ingenuity.

150. Conditions in the Lamp. — When a safety lamp
is brought into a gaseous atmosphere the gas entering the
lamp mixed with the air burns in the lamp, the products
of the combustion passing out through the discharge open-
ings at the top of the lamp. If the feed air is inflammable,
it may cause the whole lamp to fill with flame, which con-
dition is called flaming. A lamp having a free circulation
of air in and out of the lamp flames more readily, and is
said to be more sensitive to gas than a lamp in which the
free circulation of the air is obstructed by a bonnet, shield,
deflector, or other device for controlling the condition in
the lamp. The upper portion of the lamp is exposed to a
greater heat, accumulates more soot and dust, and there-
fore requires more protection than the lower portion. For
this reason the top of the gauze chimney is in most cases
provided with a gauze cap, called also the smoke gauze,
that doubles the security at that point. The gauze chim-
ney in some lamps is covered with a metal bonnet to
protect the lamp from strong air-currents. Incidentally

SAFETY LAMPS 223

the bonnet affords additional security against the passage
of flame through the gauze at the top of the lamp, by restrict-
ing the circulation and thus confining the burnt air or prod-
ucts of the combustion in the upper portion of the chimney.
This burnt air acts as a mantle to extinguish the flame at
the top of the chimney. Some lamps have their wick
flame more easily extinguished than other lamps, owing
to the readiness with which this burnt air descends in the
lamp at the slightest cause.

Not infrequently, in a lamp having a good circulation,
small balloons of flame will form above the wick flame,
when the lamp is exposed to a lively current of sharp gas,
as a gas feeder. Slight explosions will then occur in the
lamp, and these may be of sufficient violence to drive the
flame of the explosion through the gauze. It often hap-
pens that the gas entering the lamp is so sharp (unmixed
with air) that the wick flame is completely extinguished,
while the gas continues to burn in the upper portion of
the lamp where it is more diffused. As the lamp is then
withdrawn cautiously and fresher air enters the lamp below,
the flame may at times dart down from above and relight
the wick. So changeful, however, are the conditions pro-
ducing these phenomena, that they may or may not be
repeated in any given trial. The writer has had all of
these happen in his lamp within a short time, while examin-
ing very gassy workings, and then none of them return
again for a long period. The most dangerous condition
occurs usually in testing, when withdrawing the lamp
from a body of sharp gas. As the lamp is removed from
the gas and fresh air enters from below, a very explosive
mixture is often formed in the lamp. This is more apt
to occur with a closely bonneted lamp than with a lamp
having a free circulation.

224 MINE GASES AND EXPLOSIONS

One peculiar effect, alvrays noticeable within the com-
bustion chamber of a saf ei y lamp, is the diminished activity
of the combustion. The flame of the lamp is reduced in
size and intensity in proportion to the closeness of the
bonnet or chimney and the manner of circulation of air
in the lamp. The tendency of an upward current enter-
ing below the flame is to lengthen the flame somewhat,
while its volume is reduced. In some lamps the effect
of the chimney to reduce the activity of the combustion is
more marked than in others. At times, when the chimney
is first placed over the lamp the flame will diminish
and be almost extinguished, as the result of the extinctive
gases accumulating in the chimney, but this effect
quickly passes off as the circulation starts and the flame
recovers itself.

151. Influence of Wire Gauze. — In the flaming of a
safety lamp the flame may reach to the top of the gauze
chimney and fill the chimney without, however, coming
into actual contact with the metal. The absorption of
the heat of the burning gas by the cool metal reduces
the temperature of the gas in contact with it, below that
required for ignition, and the flame next to the metal is
extinguished (Art. 121). The passage of flame through
wire gauze is rendered more diflSicult, owing to the passing
gas being broken up by the fine mesh of the gauze into
numerous tiny streamlets, each of which is surrounded by
sufficient metal to abstract enough of its heat to insure
the extinction of the flame. The heat thus absorbed
is as quickly radiated outwards unless too much gas be
present, when a surplus of heat accumulates in the metal
and raises its temperature. The heating of the metal
is more rapid as the quantity of gas present in the air
is greater. The accumulation of heat in the metal soon

SAFETY LAMPS 225

destroys its power to absorb a sufficient quantity of
heat from the passing gas to extinguish the flame, and as
a consequence the flame then passes through the gauze and
ignites the gas outside of the lamp, causing what is known
as a failure of the lamp. Flame will thus pass through
a lamp gauze when heated to low redness; at this point
the temperature of the wire is somewhat above that of the
ignition point of pure marsh gas (Art. 140). When fine
coal dust is present or other gases, as olefiant gas or hydro-
gen sulphide, are mixed with the marsh gas the danger
point is reached much sooner. A dirty or oily gauze
assists the passage of the flame. A slight explosion of
gas in the lamp, or a heavy concussion of the air, a sudden
fall or jar of the lamp, especially if the gauze is dusty, or
exposing the lamp to a strong air-current, may cause the
lamp to fail and pass flame.

Mr. eTames Ashworth proved by experiments (1879) that
flame would not pass through the gauze of a Davy lamp
when exposed to an air-current containing 4.5 per cent,
of pure marsh gas and traveling at a velocity of 370 feet
per minute; but the addition of so much fine dust as
would be normally carried in suspension in a current
traveling at that velocity caused the lamp to pass the
flame in 10 seconds. This was due, in the writer's opinion,
to the additional heat produced by the combustion of the
dust and to the incandescent dust passing out through
the gauze. After experimenting with gauzes of different
sized wire Davy found that a steel wire gauze containing
28 wires (No. 28 B.W.G.) to the inch, or 784 openings per
square inch, gave the best results, and this has ever since
continued as the adopted standard wire gauze for safety
lamps. Davy stated, as the result of his protracted ex-
periments^ that ''When a cylindrical gauze is used, it

226 MINE GASES AND EXPLOSIONS

should not be more than 2 inches in diameter, for in larger
cylinders the combustion of the firedamp renders the top
inconveniently hot." He further limited the height of
the gauze to 7 inches. The generally adopted standard
gauze for Davy lamps is IJ inches in diameter and 41
inches high, not including the gauze cap. In the Clanny
lamp the height of the gauze is about 4 inches.

152. Testing Safety Lamps. — Any imperfection in a
lamp gauze, which may be so small as to easily escape
detection by the eye, will at a critical moment cause the
lamp to fail. It is therefore necessary that all safety
lamps should be tested to ascertain their perfect security
before they are allowed to be taken into the mine. The
only safe plan is to do this regularly with every lamp after
the same is lighted and before it is given out at the lamp
house.

It is not likely that a colliery will be provided with
an elaborate lamp-testing apparatus as part of its equip-
ment, and therefore it is not generally possible to carry
out exhaustive tests as to the velocity of explosive mix-
ture that lamps will withstand, etc. But if the lamps
are carefully selected, in the first instance, of a good
and approved type, such tests are not necessary. At the
same time it is well to have a means of testing the lamps
from time to time, more with a view of detecting the
defects that may have come into existence with wear
and tear, or through carelessness in handling or fitting
together. For this purpose a strong wooden box may
be used, with a trap door at the top opening upwards,
and a door at the side fitted with a window of stout glass
to observe the test. Coal gas or feeder gas mixed with air
in any proportions desired, can be passed through the
box and some means provided at the end of the box for

SAFETY LAMPS 227

producing a current of any desired velocity. Lamps to be
tested are put in singly. A defective lamp will ignite
the explosive mixture in the box and the trap door will
be blown open by the explosion. There should also be
at hand suitable means for the daily testing of all safety
lamps taken into the mine.

CLASSIFICATION OF SAFETY LAMPS

153. Classification. — All safety lamps may be divided
into two general classes, according to the use for which
they are designed :

(a) Lamps for testing for gas;

(b) Lamps for general use.

From the nature of the conditions a good lamp for
testing does not make a good lamp for general work. The
test for gas by means of a safety lamp requires that the
lamp be sensitive to gas; the gas must have ready access
to the flame, and the condition within the lamp must rep-
resent correctly the condition of the air outside of the
lamp. In order that this may be the case, the lamp must
be so constructed as to permit of a good circulation of air
in and out of the lamp. On the other hand, a good lamp
for general work must be less susceptible to the presence
of gas; the chief purpose of this lamp is to give light
and protection. Thus it is clear that the conditions
and requirements of these two classes of lamps are essen-
tially different. ^

154. Lamps for Testing for Gas. — The principal require-
ment of a lamp designed to be used exclusively for testing
for gas, as explained above, is, such a circulation of air
through the lamp as will insure the same gaseous con-
dition of the air surrounding the flame within the lamp
as that of the air outside of the lamp. This is necessary

228 MINE GASES AND EXPLOSIONS

in order that the indications of the flame as observed
within the lamp shall correctly represent the state of the
mine air with respect to gas; it is the first requirement of
a testing lamp, and practically determines its sensitiveness.
This freedom of circulation is best secured by arranging
for the free admission of the air and gas, either through
the lower portion of the gauze chimney at a point not
above the flame, as in the Davy lamp (Art. 157), or
through openings in the lamp itself at a point below the
flame, which may be called the Eloin principle (Art. 155)
though adopted also in other early lamps.

The second requirement of a testing lamp relates to the
protection that its construction must afford, firstj against
strong air-currents or a concussion of the air; second^
against the transmission of flame at the top of the lamp,
which is the danger point for all lamps. The danger of
the transmission of flame through any portion of the
gauze chimney is always greater in a testing lamp, because
its continued and repeated exposure to bodies of gas often
renders the lamp very hot, so that, in the writer's expe-
rience, it could not be held comfortably in the hand. Pro-
tection against air-currents and concussion of the air is
best secured by a shield, which should be movable, so that
it can be slid up and down outside of the gauze, as the
condition of the mine may require, as in .the Hughes Evan
Thomas lamp (Art. 157). Protection against transmission
of flame is best secured by the use of a double gauze chim-
ney, which, as will be seen later, is the characteristic feature
of the Marsaut lamp (Art. 162).

The third requirement of a testing lamp relates to the
accurate measurement of the height of the flame cap
produced by the gas present in the air. The height of
this flame cap increases with the percentage of gas present^

REQUIREMENTS OF TESTING LAMPS 229

and thus furnishes a means of determining that percent-
age more or less closely, according to the accuracy of the
measurement of the height of the cap. It has been the
custom for a long time to guess at the percentage of gas,
or rather guess at the relative gaseous condition of the
mine air from the appearance of the cap. This flame cap,
however, cannot be discerned by the ordinary observer
when less than 2 per cent, of gas is present in the air;
others cannot detect the cap with certainty under 2.5 per
cent., and many fire bosses report "no gas" for anything
under 3 per cent., being unable to see the faint, non-
luminous cap formed above the flame by the gas till a
dangerous proportion of gas is present in the air. This
method clearly depends wholly on the observer's ability
to discern the cap, and to correctly measure its height with
his eye, making possible a twofold error at any time.
In a recent discussion of this subject that took place in
a meeting of the Institution of Mining Engineers, Eng-
land,* it was stated that the observance of a small flame
cap by two individuals will differ according to the object
each has in view. An instance was cited where a mine
inspector and a mine overman, both experienced mining
men, entered a place where the inspector wanted to show
the presence of gas; the overman failed to detect the
flame cap, which was plainly visible to the inspector.
Shortly after, the inspector failed to see any appearance
of gas on the flame in the overman's lamp in another
heading where the latter claimed he had found gas. As
a matter of fact, there is too much guessing in the method
of detecting the presence of gas by the height of the flame

* Transactions of the Institution of Mining Engineers, Vol. xxvi.,
p. 217.

230 MINE OASES AND EXPLOSIONS

cap, which is very indistinct except when the proportion
of gas reaches 3 per cent.

An important requirement of a good testing lamp is
therefore some simple means of gauging the height of the
flame cap and, if possible, indicating the presence of small
percentages of gas. Any device for this purpose must be
simple, inexpensive, and adapted to a small lamp of light
weight, such as a fire boss would use in making his rounds.
These requirements are met in the simple Beard-Mackie
Sight Indicator (Art. 204). Some special testing lamps
have been devised to burn alcohol, naphtha-benzine, or
hydrogen, so as to render the flame more sensitive to small
percentages of gas. Such are the Pieler, the Stokes, and
the Ashworth lamps burning alcohol; the Wolf lamp
burning naphtha-benzine, and the Clowes hydrogen lamp.
The flames of all of these lamps, however, are easily ex-
tinguished and require extra care in making the test for
this reason. They are besides, for the most part, expen-
sive, heavy, and inconvenient.

155. Lamps for General Use. — The first requirement of
a safety lamp for general use is maximum illuminating
power consistent with conditions of safety. This should
not depend on the burning of a highly volatile oil. Such
an oil, even when absorbed in cotton, is a menace to safety,
either from a possible leak or from the explosive vapor
that fills the combustion chamber of the lamp, after the
lamp has been extinguished for a short time, and which
causes the lamp to flash when it is relighted. Good illu-
mination should be secured by improving the circulation
in the lamp, and by so arranging the admission of air
to the flame that the circulation in the lamp will always
be ascensional. By this means there will be no conflict-
ing air-currents within the lamp, and the common ten-

REQUIREMENTS OF WORKING LAMPS

231

dency of the lamp to smoke will be largely avoided. The
majority of the working lamps in common use admit the
air at a point above the flame, and to reach the flame
this air must pass downwards in the lamp. A few lamps
are designed on what may be called the Eloin principle;
these lamps admit the air through gauze-protected open-
ings at a point below the flame. By this method a direct
upward draft is produced, the circulation in the lamp
is wholly ascensional, and the illuminating power of the
lamp is greatly improved.

In Fig. 20 the arrows show the manner in which the air
enters the lamp through the openings o in the lower ring
c of the chimney, and passes upwards through openings
in the plate a into the combustion chamber m. The ring
c is provided with two threads of
slightly different diameter, the
one above the openings o for hold-
ing the plate a, which supports
the glass chimney b, and the other
below the openings for holding
the oil vessel v. The standards
s, which support the upper plate
forming the base of the gauze
chimney above the glass, are
firmly riveted into the base of the
ring c. Flat washer rings of
asbestos are fitted
and above the glass chimney b, so
as to make a tight joint. The
openings o are protected by a gauze ring that fits snugly
inside the ring c. The wick tube w is supported by a
thin brass disk fastened to it near its lower end. This
disk fits within a collar turned on the upper surface of

underneath Fig 20.-Showing Principle
of Eloin Safety Lamp ad-
mitting Air below the
Flame

232 MINE GASES AND EXPLOSIONS

the oil vessel, and is held in place by the nipple n, which
screws into the collar. The small rod p running up
through a fine tube brazed into the oil vessel is the
pricker for raising and lowering the wick to regulate the
flame.

Good illiunination requires that the lamp flame be set
sufficiently high in the combustion chamber not to cast
too wide a shadow on the floor.

The second requirement of a good working lamp is security
against strong air-currents. The most common form of
protecting the lamp in this respect is to incase the gauze
chimney in an iron or steel bonnet provided with suitable
openings at the top of the bonnet for the escape of the
products of combustion from the lamp. The bonnet in-
cidentally restricts the outflow or discharge from the
lamp, and thus affords an additional protection against
the transmission of ffame at the top of the lamp. Instead
of the bonnet, or sometimes in addition to the bonnet,
double gauzes or triple gauzes are used, as in the Marsaut
lamp. A good protection against explosion of gas in the
lamp is the sheet-iron, conical chimney of the Mueseler
lamp (Art. 167); but this lamp is easily extinguished by
canting to one side, owing to the change that then takes
place in the circulation in the upper portion of the lamp,
which drives the burnt air and gases downwards upon
the flame. The bonneted Marsaut lamp when properly
constructed will give as great protection as any means
thus far employed.

The third requirement relates to simplicity of con-
struction, an important element being the fewness of parts.
The parts of a safety lamp should, as far as practicable, so
depend one on another that the lamp cannot be put to-
gether without all its parts being in place. It should be

TYPES OF SAFETY LAMPS 233

practically impossible to put a bonneted lamp together
and omit the gauze; but with certain lamps this has
been done inadvertently. To avoid accident arising from
such oversights and from any slight defect in the gauzes
or glass, it should be customary to regularly test every
lamp in a box, through which is made to pass a current of
feeder gas diluted to its most explosive point. It is not
sufficient, as has been done in some instances, to expose
the lamp while burning to a jet or blower of gas to see
whether the gas would be ignited. The issuing gas is
diffused so rapidly into the air that the chances of ignition
taking place through any possible defect in the lamp
coverings are very slight. In one instance a lamp having a
hole the size of a slate pencil punched purposely in the
top of the gauze failed to ignite a piped jet of feeder gas
to which it was exposed for some time. The lamp must
be surrounded by an atmosphere of gas at the explosive
point in an inclosed space, in order to detect any possible
defect in the lamp.

A fourth requirement is that a lamp for general use in
the mine should be provided with a lock fastening that will
plainly reveal any attempt to open the lamp. Of the dif-
ferent forms of locks that have been employed the lead-
plug lock (Art. 178) seems to give the best satisfaction,
because of its simphcity and the security it affords, which
is as great as that of any other lock.

TYPES OF SAFETY LAMPS

156. In the following description of the different types
of safety lamps no attempt will be made to separate lamps
that are specially adapted to the work of testing for gas
from those adapted to general work, since some are adapted
and designed to meet the requirements for both purposes.

234

MINE GASES AND EXPLOSIONS

The description of each lamp will have particular reference
to its distinctive features, and only those lamps will be
described that possess such features, or have come into gen-
eral use.

157. The Davy Lamp. — ^This lamp consists of an oil
vessel of brass or aluminum surmounted by a cylinder of
wire gauze to which it is attached by a screw joint. Fig. 21
shows an unbonneted Davy and a sectional elevation of

View Section

Fig. 21. — Unbonneted Davy Lamp

the same, the arrows indicating the circulation of the air
in and out of the lamp. The wire gauze forming the
chimney in the standard Davy lamp is 1^ inches in
diameter and varies from 4J to 6 inches in height, the

THE DAVY LAMP

235

former beiiig used in what is called the iire-hoss Davy
(Fig. 22). A still smaller sized lamp called the pocket Davy
has a gauze 4 inches high. In each case the gauze is sur-
mounted by a gauze cap to afford greater protection at
the top of the chimney. As shown in the figure, the lamp
has three standards or upright rods that serve to unite the
upper and lower rings supporting the gauze. The bale
or handle of the lamp is attached to the hood that protects
the top of the chimney from falling dust and dirt or water.
The distinctive feature of the Davy lamp is its large gauze
area, admitting of a free circulation of air in and out of the
lamp, and making this lamp extremely sensitive to gas.
The condition within the lamp represents correctly the
gaseous condition of the outer air,
and for this reason the unbonneted
Davy makes the best form of test-
ing lamp. Owing to its sensitive-
ness the lamp flames readily, and is
therefore a dangerous lamp to place
in the hands of the ordinary miner,
or to use at the working face for any
purpose other than testing.' The un-
bonneted Davy lamp is unsafe in an
explosive current, having a velocity
exceeding 6 feet per second, or
360 feet per minute. The different
forms of protected Davy lamps are
able to withstand current velocities
varying from 600 to 1,200 feet per
minute. The tin-can Davy has
successfully withstood a velocity
of 2,000 feet per minute without causing an explo-
sion. The illuminating power of the Davy lamp will

Fig. 22.— Fire-boss
Davy Lamp

236 MINE GASES AND EXPLOSIONS

not average above .16 candle power. The use of the Davy
lamp in the mine, except for the purpose of testing for gas,
is prohibited by the bituminous mining laws of Pennsyl-
vania; the mining laws of England permit of the use of the
bonneted Davy only, for testing for gas; and in France and
Belgium the Davy is wholly excluded from the mine. The
Davy lamp is constructed to burn sperm or lard oil or
colza. Numerous types of the Davy lamp have used
different forms of oil vessels; that known as the New-
castle had a wide expanding base (Fig. 21); another
type has a straight oil vessel (Fig. 20); while the Ameri-
can fire-boss Davy has usually an oil vessel shaped like
a dice box (Fig. 22).

In England, various forms of cases have been used for
shielding the Davy. One of these, an early form called
the Davy in case, or the tin-can Davy, consisted of a
metal shield covering the entire lamp and provided with a
glass window in one side, which gave the lamp the appear-
ance of a lantern. Another form was similar to the first,
except that the window was replaced by a glass cylinder
that encircled the lamp, giving it the appearance of a
bonneted Clanny lamp. Still another form consisted of
the ordinary Davy, but having a glass cy Under surround-
ing the gauze chimney for its full height; it was called
the Davy with glass shield. The Davy Jack or Jack Davy,
sometimes called the fire tryer^s or gas finder'' s or fireman's
lamp, was a Davy of smaller size corresponding to the
American fire-boss Davy and the pocket Davy. These
small sizes of Davy lamps heat quickly and are not safe
in presence of much gas. Fire bosses often prefer them
for their small size, which allows of the lamp being
carried in the pocket, or held in the teeth when climbing
over falls.

THE DAVY LAMP

237

A Davy lamp with bonnet and glass shield, that has given
good satisfaction both here and in England, is shown in
Fig. 23. This lamp was designed by Mr. W. S. Hughes,
Scranton, Pa., who was at the time he designed the lamp
associated with Mr. Evan Thomas, England; the lamp has

View Section

Fig. 23. — Hughes-Evan Thomas Lamp

thus come to be known as one of the many Evan Thomas
lamps. The lamp consists of a common Davy provided
with a special wide brass ring at the base of the gauze
chimney. This ring has openings for the admission of air
on the Eloin principle, as shown by the small arrows,
and is joined by standards to another ring at the base of
the bonnet. The lower ring screws onto the top of the oil
vessel in the usual manner, while the upper ring is threaded

238

MINE GASES AND EXPLOSIONS

to receive the bonnet. Holes for the admission of air, as
shown by arrows, are made in the lower portion of the
bonnet, while at the top somewhat larger holes are pro-
vided for the escape of the products of combustion.
The interesting and useful feature of the lamp is the
sliding glass chimney that rests on
the lower ring and extends to just
above the upper ring, thus sur-
rounding the lower half of the
gauze, below the metal bonnet, and
affording the much-needed protec-
tion of the flame from strong air-
currents. When desired in testing
for gas in chambers or rooms
where the air has a more moderate
velocity, the glass cylinder can be
raised so as to occupy the space
between the bonnet and the gauze,
and is held in this position by the
small pin a operated by the spring
b. This leaves the air free to enter
the lamp through the lower por-
tion of the gauze, and makes an
excellent testing lamp when prop-
erly used.

The Scotch Davy (Fig. 24) was
for a long time a favorite lamp
in the mines of Scotland. The lamp has an extremely
home-made appearance, but its particular point of in-
terest is the fact that it was constructed contrary to
the results obtained by Davy in his experiments (Art.
151). The diameter of the gauze of the Scotch Davy
was 2.9 inches and its height 10 inches to the base of the

Fig. 24.— The Scotch
Davy Lamp

THE STEPHENSON LAMP 239

conical cap. This height was afterwards reduced to 7
inches, but the actual length of gauze exposed was only 4^
inches, owing to a rim of sheet copper 2 inches wide at
the bottom of the chinmey, and another metal band J inch
wide at the top. The gauze was fastened by heavy rivets,
and a double thickness of gauze was used at the top of
the cap. This covering set tightly into a cup of sheet cop-
per, holding a socket or pedestal 1| inches in height, which
could be used either to support a tallow candle or an oil
lamp. The lamp used was a small tin oil vessel having a flat
burner; to the side of this vessel was attached a tin shield
shaped like a round-pointed spade to protect the flame of
the lamp from a strong draft. Accidents that were trace-
able to the use of this lamp in the mine, finally (1886) led to
the appointment of a committee to investigate the subject
and recommend a proper lamp as a substitute for the one
in use. So strong was the prejudice, however, in favor of
the lamp, that a number of colliery officials were found
who were strongly opposed to giving up the old lamp. The
incident serves to illustrate the strong prejudice that
exists generally among practical mining men that leads
them to oppose the adoption in the mine of something
that is unfamiliar and untried. This prejudice is not
scientific, but is born of environment.

158. The Stephenson or "Geordie" Lamp. — There is
no accurate description of the original Stephenson lamp
at hand. This lamp was ordered made from Stephen-
son's drawings, October 2, 1815, and tried in a gas blower
at Killingworth Colliery, October 21, without satisfactory
results. The lamp admitted its air through a half -inch
tube in the bottom of the lamp, the tube being provided
with a sliding tip to reduce the size of the opening. Some
alterations were then made and the lamp again tried in

240 MINE GASES AND EXPLOSIONS

the same blower, November 9, with but sHght if any im-
provement in the burning quaUties of the lamp. The
theory on which Mr. Stephenson operated was that by
confining to a certain extent the products of the combus-
tion in the upper part of the lamp, and restricting the in-
flow of air and gas below, the flame of any gas burning
in the lamp would be prevented from passing upwards and
out of the lamp by the extinctive gases in the top.

The present Stephenson, or "Geordie" lamp as it is
commonly called, resembles in its outward appearance the
Davy lamp. The gauze chimney is 2.1 inches in diameter
and 6i inches high, and has no gauze cap above or smoke
gauze, as this cap is frequently called. The gauze chim-
ney incloses a very slightly conical glass chimney 1.9
inches in diameter and 5 inches high. This glass chimney
is surmounted with a perforated copper cap that takes
the place of the smoke gauze. The glass chimney is loose
within the gauze, and in most of these lamps can be raised
slightly, so as to admit air more freely at the bottom.
The lamp is arranged to burn ordinary sperm or lard oil.
It is a great favorite with some fire bosses and is still
used in certain localities in Pennsylvania for the pur-
pose of testing. It is claimed by those who use the
lamp that it is superior to the common Davy for this work.
The glass, however, produces a reflection that interferes
with the careful observance of the flame cap. Its illumi-
nating power is less than the Davy, being about .10 candle
power.

159. The Clanny Lamp. — The improved Clanny lamp
is the most common form of safety lamp for general work
and the most widely used, owing to its simplicity. It is
an essentially different lamp from that first designed by
Dr. Clanny (Art. 146). In his improved lamp Dr. Clanny

THE CLANNY LAMP 241

adopted the wire-gauze chimney of the Davy lamp,
replacing therewith the conical cap of his first lamp; he
also substituted for the glass window of his first lamp a
cylinder of glass. There was now no further need of the
bellows attachment for forcing air into the lamp, as the
circulation was natural. The improved lamp was in fact
a Davy lamp, in which the lower portion of the gauze was
replaced by a glass cylinder 2 J inches in diameter and the
same height, leaving practically a 4-inch gauze above the
glass. This greatly improved the illuminating power of
the lamp, making it in this respect much superior to the
Davy; it also gave added protection to the flame, adapt-
ing the lamp better to the purposes of general work, as
this lamp was less sensitive to gas.

Fig. 25 shows a view and sectional elevation of an
unbonneted Clanny lamp. As indicated by the arrows,
the air enters the lamp through the lower portion of the
gauze and must descend to reach the flame, while the
products of combustion rising in the center of the lamp
pass out through the top of the gauze. These two con-
flicting currents create in the lamp a tendency to smoke,
which dims the glass and reduces the illumination. The
lamp is provided with a gauze cap to give greater pro-
tection at the top of the chimney where the heat and
pressure of the ascending currents are greatest. An or-
dinary pricker for raising and lowering the wick passes
up through the oil vessel as shown. The lamp is usually
constructed to burn ordinary sperm or lard oil, except
when, for a special purpose, another illuminant is desired;
the oil vessel must then be adapted to the purpose. A
flat burner is frequently used in this lamp instead of the
round burner shown in the figure. The lamp is used
with or without a bonnet, according to the conditions

242

MINE GASES AND EXPLOSIONS

in the mine where it is used. The unbonneted Clanny
is unsafe in an explosive current having a velocity exceed-
ing 8 feet per second or 480 feet per minute. The letters

View Section

Fig. 25. — Improved Unbonneted Ganny Lamp

in Fig. 25 correspond to those used in Figs. 19 and 20
and already explained in Arts. 149 and 155.

The various types of bonneted Clanny lamps afford
security varying with the construction of the lamp, and
are able to withstand current velocities varying from
1;500 to 2,000 feet per minute. Some makes of this
lamp have been provided with tangential openings in
the bonnet for deflecting the air as it enters the lamp,

THE EVAN THOMAS LAMP

243

which feature has increased its security. The illuminating
power of the different types of Clanny lamps varies from
.25 to .50 candle power, depending on the form of con-
struction. The use of the unbonneted lamp is prohibited
by the bituminous mining laws of Pennsylvania; the
lamp is practically debarred from
the mines of Great Britain, and is
wholly excluded from the mines of
France and Belgium.

i6o. The Evan Thomas No. 7. —
There are a large number of lamps
known under the general name of
the Evan Thomas lamp. For the
most part these are all some modi-
fication of the bonneted Clanny
lamp. One of these, known as the
Evan Thomas No. 7, has been found
to give a much greater amount of
security than other forms of bon-
neted lamps with single gauze chim-
neys. The characteristic feature of
the lamp is the special manner of
protecting the intake and the dis-
charge openings, so as to maintain
an atmosphere within the lamp
wholly undisturbed by the move-
ment of the air outside. The letters
in this figure are the same as those used to indicate the
corresponding parts in Figs. 19 and 20. As indicated by
the arrows, the air enters the lamp through the openings
0 in the lower end of the bonnet; here it strikes the brass
deflector ring d that encircles the lower portion of the
gauze g. The deflector is secured to the gauze by the screw

Section

Fig. 26.— Evan Thomas

No. 7

244 MINE GASES AND EXPLOSIONS

collar r; at its top is a broad flange that almost closes
the space between the gauze and the bonnet. Through
this annular opening rV inch wide the air entering the lamp
must pass before it reaches the gauze, where it enters
the combustion chamber m above the flame. The open-
ings u Sit the top of the bonnet, for the discharge of the
products of combustion, are protected within by a conical
deflector i, over which the heated gases must pass, through
a narrow slit between the deflector and the top of the
bonnet. The gauze g is surmounted by a smoke gauze or
cap t, which fits tightly over the main gauze, and is gener-
ally indented as shown, to prevent its slipping down too
far and blocking the gauze below where the air must
enter the lamp.

In this lamp is realized the principle of the Stephenson
lamp, since the flame is extinguished just above the lower
edge of the smoke gauze where it loses the oxygen of the
entering air. On this account but a small area of the
gauze is heated by proximity to the flame, which fact
greatly increases the security of the lamp. This lamp
has been tested and did not fail, in an explosive current
having a velocity of 3,200 feet per minute. The flame
continues to burn steadily, even when the lamp is con-
siderably inclined from the vertical, and is extinguished
only when a horizontal position has almost been reached.
Swinging the lamp, or rapid upward or downward motion
does not seriously affect the flame. The lamp has an
illumination of .40 candle power. Like all Clanny lamps
of this type it has a tendency to smoke, owing to the
conflicting currents, as shown by the arrows. The bon-
net is arranged to screw on the base of the deflector ring,
to which also the standards s are attached. The same
ring also forms the upper seat for the glass chimney b.

THE BULL'S EYE (MAUCHLINE) LAMP 245

One of the standards is made movable and lengthened;
so as to pass through the base ring c, and by this means
the bonnet is locked when the oil vessel is screwed in
place, by the standard being forced upwards into a hole
in the ring I, which forms the bottom of the bonnet.

What is now known as the Cambrian lamp is a modifica-
tion of the No. 7 lamp shown in Fig. 26. In the Cambrian
lamp the deflector or cylindrical baffler has been removed,
because it checked the current or circulation in the lamp
and reduced its illuminating power. This lamp has also
been fitted with an automatic air lock, which locks as
the oil vessel is screwed into place, but which requires a
powerful air pump to unlock the same (Art. 178).

Another form of Evan Thomas lamp is a bonneted Qanny
similar to that shown in Fig. 26, except that the lamp
has two glass cylinders, one within the other, with a
thin annular air space ^ inch wide between them. There
is no deflector d to deflect the entering air upwards, but
the air passes down between the two glass cylinders and
enters the combustion chamber at a point below the flame.
This arrangement not only keeps the glasses cool and
perhaps improves their power to transmit light, but avoids
the tendency of the flame to smoke by creating a direct
circulation upwards through the combustion chamber and
thus greatly improves the illuminating power of the
lamp.

i6i. The Bull's Eye (Mauchline) Lamp. — This lamp.
Fig. 27, does not differ in principle from an ordinary Clanny
lamp. The lower portion of the lamp casing, however,
consists of a brass cylinder a, having a strong convex
lens 6, about 2 inches in diameter inserted in and form-
ing the front of the lamp; two small round openings c,
one on each side of this casing and protected by wire

246

MINE GASES AND EXPLOSIONS

gauze afford opportunity to observe the flame. A re-
flector d, at the back of the lamp, behind the flame,
concentrates the hght rays on the
lens. As shown in the figure, the
metal casing is surmounted by
a gauze chimney g and cap t, similar
to the ordinary Clanny lamp. The
air enters the lamp by the gauze
openings c, at the side, as well as
through the lower portion of the
gauze chimney. The lamp is gen-
erally used without a bonnet; it
throws a strong light in one direc-
tion only, and was designed by Mr.
Mauchline as a surveyor's lamp.

162. The Marsaut Lamp. — ^The
bonneted Marsaut (Fig. 28) is to all
outward appearance a bonneted
Clanny, but the sectional view on
the right shows that the inner con-
struction differs from that of the
Clanny by having more than one
gauze forming the chimney. The
lamp shown in the figure has three
gauzes; other Marsaut lamps have
but two gauzes. The multiple gauze is the characteristic
feature of this lamp. In all other respects the lamp is
identical with the Clanny lamp. The lamp may be used
with a bonnet as shown here, or where the conditions are
such as not to require the protection afforded by the
bonnet this is omitted. The unbonneted Marsaut is
much safer for common use than an unbonneted Clanny
lamp, although no unbonneted lamp should be used

Fig. 27. — Mauchline's
Bull's Eye Clanny
Lamp

THE MARSAUT LAMP

247

under conditions where the gauze will be exposed to
much dust and dirt. An unbonneted lamp in constant
use should have its gauzes carefully cleaned at the end
of each shift.

The multiple gauzes of the Marsaut lamp are a great
protection to the upper portion of the lamp, as the space

View Section

Fig. 28. — Bonneted Marsaut Lamp — Three Gauzes

between the gauzes becomes filled with extinctive gases,
especially where the lamp is bonneted or the intake open-
ings are at all restricted. The multiple gauze chimney
has been found by the writer to be extremely valuable for
the protection of lamps that admit the air below the flame,
and thus have a strong draft naturally. On this account

248 MINE GASES AND EXPLOSIONS

any lamp built on the Eloin principle of admitting the
air below the flame should combine with this the principle
of the multiple gauzes of the Marsaut lamp. The two-
gauze Marsaut has been found to be safe in an explosive
current having a velocity not exceeding 2,600 feet per
minute, while the three-gauze lamp has easily withstood
a velocity of 3,100 feet per minute, without showing any
signs of failing, after an exposure of two minutes, the
inner gauze being then a bright red and the second gauze
a dull red, while the outer gauze remained dark and
cool. The illuminating power of the two-gauze lamp is
.70 candle power when first lighted, reducing to .60 after
burning a half -hour; while that of the three-gauze lamp
is about .50 candle power, reducing after a half-hour to
.45. Like the Clanny this lamp has been commonly de-
signed to burn ordinary sperm or lard oil, but at times,
for special purposes, the oil vessel has been adapted to
burn a more volatile oil.

163. The Gray Lamp. — Primarily the Gray lamp con-
sists of a bonneted Marsaut having two gauzes but ad-
mitting the air below the flame on the Eloin principle.
The distinctive feature of the lamp consists of the large
hollow tubes, which serve the double purpose of stand-
ards and of conducting the air into the lamp from a point
nearer the top of the lamp. Fig. 29 shows the Gray No. 2
lamp, in which the tubes extended only to the base oi
the bonnet; the lamp is shown here in sections so as to
make clear its construction. The tubes forming the
standards of the lamp are called the Gray inlet tubes.
Later a single tube was added, extending one of the stand-
ard tubes to the top of the bonnet, which enabled the
lamp to draw its air from above and thus to test a thin
layer of air at the roof for which purpose the lamp was

THE GRAY LAMP

249

designed. The glass of this lamp was a cylinder, as was
also the outer gauze, while the inner gauze was conical as
shown. The bonnet is made to screw onto the upper
plate above the standards. The openings in the bonnet
are punched in such a way as to deflect the entering air
and break the force of a strong air-current or concussion

Bonnet Removed Lamp and Chimney
Fig. 29.— Gray No. 2 Lamp

of air. This is the Ashworth bonnet. As appears in the
figure, the openings are arranged in two sets, the lower
being the intake and the upper the discharge openings. On
the inside of the bonnet is a shield dividing the two and
deflecting the intake air downwards to the tubes, which
lead to the combustion chamber entering this below the
flame.

250 MINE GASES AND EXPLOSIONS

The Gray lamp is made to burn sperm or lard oil; its
illuminating power is .38 candle power when first lighted,
but reduces in a short time to .33 candle power. The
flame of the lamp is not much affected by inclining the
lamp, or by swinging, or by rapid motion up and down.
The lamp has been tested without causing an explosion
in an explosive current having a velocity of 3,000 feet
per minute; the glass, however, was cracked by the heat,
but the lamp did not fail during an exposure of 1 min.,
40 sec.

An annoying feature of the Gray lamp was that when
the lamp was introduced into a body of sharp gas, the
gas entering the lamp would extinguish the flame
before the lamp could be withdrawn and pure air could
reach the combustion chamber. This was largely or
wholly due to the fact that no pure air could reach
the flame till all the gas filling the inlet tubes had passed
into the lamp, which was sure to extinguish the light.
This and other considerations led later to the construc-
tion of a lamp combining the best features of the Gray
and the Ashworth lamps.

164. The Ashworth Lamp. — ^This was primarily a test-
ing lamp though used also for general work. The dis-
tinctive features of the lamp (Fig. 30) were a double
bonnet, the outer one a being perforated in different ways
and having a greater or less number of holes 0 for the admis-
sion of air to the annular space between the two bonnets,
and the inner one t having holes p at the bottom through
which the entering air reached the combustion chamber
m, and being surmounted by a truncated cone i that
reached almost to the discharge openings u in the top
of the bonnet. The conical glass chimney b was sur-
mounted by a small conical gauze g. In this lamp the

THE ASHWORTH LAMP

251

usual pricker was replaced by an arbor carrying two
toothed wheels for moving the wick up or down when
alcohol was used. Three forms of oil vessels v were used
in this lamp, designed to burn paraffin spirit, or oil,

View Section

Fig. 30. — The Ashworth Testing Lamp

respectively. These oil vessels are shown in Fig. 31. The
illuminating power of Ashworth No. 4 lamp was .68 after
being lighted a few minutes, but this reduced to .55 after
burning half an hour.
The particular Ashworth features in these lamps are

252

MINE GASES AND EXPLOSIONS

the conical glass and the double bonnet, the inner bonnet f
being surmounted by a truncated cone i. Conical gauzes
had been used in earlier lamps. The lamp, though possess-
ing admirable features, was prone to go out when inclined
to a considerable angle from the vertical, owing to a change
being produced in the circulation, which brought the
burnt air and gases from the top of the lamp down on the
flame. There were other forms of Ashworth lamps that

Paraffin Alcohol Oil

Fig. 31. — Vessels of the Ashworth No. 4 Lamp

differed from each other in unimportant details. The
Ashworth tester, burning oil and alcohol (Fig. 42) will
be described later.

165. The Ashworth-Hepplewhite-Gray Lamp. — This lamp
combines the best features of the Gray and Ashworth
lamps described above. The short pattern A-H-G lamp
is shown in sections, in Fig. 32, which makes clear its
essential features. On the left of the figure is shown the
oil vessel and resting on this a gauze ring, through which
the air brought down the inlet tubes or standards enters
the combustion chamber. Above the gauss ring is a plate
that forms the seat for the conical glass chimney sur-
mounted by the inner bonnet of the Ashworth lamp.

THE ASHWORTH-HEPPLEWHITEGRAY LAMP 253

This inner bonnet, as shown, is a cyhnder topped with a
truncated cone. Within the inner bonnet is the small
conical gauze. In this lamp, unlike the Ashworth lamp,
the intake air does not enter through the gauze chimney,
but passes down the standards and finds admission below

Bonnet Removed Lamp and Chmmey

Fig. 32. — Ashworth -Hepple white-Gray Lamp — Short Pattern

the flame. The entire gauze area above is therefore
available for discharge, which makes possible a smaller
gauze. The space between the inner bonnet and the
gauze chimney is, moreover, a great source of protection,
because the gauze is completely surrounded, in fact im-
mersed, in an extinctive atmosphere of burnt air and gases

254

MINE GASES AND EXPLOSIONS

that prevents the flame of any gas burning in the lamp
from approaching the gauze. This extinctive zone at
the top of the lamp illustrates the Stephenson principle,
and acts as a mantle to protect the discharge area against

the transmission of flame.
This condition is main-
tained more certainly by
the contraction of the dis-
charge area at the top of
the cone, which increases
the velocity of discharge
and completely divides the
intake air from the gases
discharged from the lamp,
without making it neces-
sary to insert a soHd parti-
tion to accomplish this
purpose. In this respect
the lamp represents the
most perfect construction
of any safety lamp now
made.

Mr. Ashworth recog-
nized that '' Theoretically
the Gray arrangement was
the best for obtaining ac-
curate indications of the
state of the air close to the roof; but practically it was
wrong, because when gas entered the tubes it was com-
pelled to pass through the lamp before any fresh air
could enter."* To overcome this diflftculty one or more
of the Gray inlet tubes of the A-H-G lamp were provided,

Fig. 33. — Showing Manner of Testing
for Gas with the A-H-G Lamp

* J\lining Accidents, Abel, page 73.

THE ASHWORTH-HEPPLEWHITE-GRAY LAMP 255

at Mr. Ashworth's suggestion, with openings at their base
that could be closed with slip muffs, as shown in the figure.
This form was particularly convenient and practical when
making a test for gas, because with the slides pushed up

View Section

Fig. 34 —Standard A-H-G Lamp

and the openings partly covered by the forefinger and
thumb, as shown in Fig. 33, it was possible to so control
the admission of the air and the gas as to prevent the
extinction of the flame.

256 MINE GASES AND EXPLOSIONS

Fig. 34 shows the standard A-H-G lamp. In this lamp
the outer bonnet is omitted, the inlet tubes being here
carried to the top of the lamp, where they terminate in
the plate to which the bale of the lamp is shown as attached ,
Above this is another closely fitting plate provided with
holes corresponding to the inlet tubes below; this is the
cut-off plate for opening or closing the tops of the tubes.
A small pin fixed in the lower plate fits the cut shown in
the upper one and Hmits the movement of* the cut-off
plate. When the tops of the inlet tubes are closed and
the slides at the bottom of the lamp pushed up, air enters
the lamp through the lower openings, but when testing
for gas close to the roof the lower openings are closed and
the cut-off plate shifted to admit air at the top of the
tubes. The plain brass cylinder shown between the stand-
ards above the glass chimney is the inner bonnet shown
on the right in Fig. 32, and has the same form as that
bonnet, terminating in a truncated cone within the hood
that covers the top of the lamp, as shown in the sectional
view on the right, Fig. 34.

Fig. 35 shows two of the most recent forms of the A-H-G
lamp. These have a single inlet tube, in each case, there
being but three standards instead of four as in previous
lamps of this type. Two of these standards are made
of light No. 7, B.W.G. brass wire, so as to reduce to a mini-
mum the obstruction of the light by the uprights. The
illuminating power of these lamps is high, being given
as .79 candle power. The resistance of the lamp to ex-
plosive currents having a high velocity is remarkable.
The lamp is said to have successfully withstood a current
velocity of 6,000 feet per minute, which is about double
the velocity at which other lamps have been tested. The
A-H-G lamps are generally designed to burn ordinary

THE BEARD DEPUTY LAMP

257

sperm or lard oil, but are sometimes fitted with oil vessels
specially designed to bm*n some form of methylated
spirits, alcohol, naphtha or benzoline.

In what manner Mr. Hepplewhite's name became con-
nected with this lamp does not appear. Mr. Hepplewhite
was mine inspector at the time when Mjr. Ashworth and
Mr. Gray brought out their joint lamp under the name
of the Ashworth-Hepplewhite-Gray lamp, and it may

Fig. 35
Improved A-H-G Lamps

have been in recognition of some suggestion of improve-
ment or use of the lamp.

i66. The Beard Deputy Lamp. — This lamp is a Marsaut
lamp designed by the author on the Eloin principle, for
the purpose of producing a safe working lamp that would
give at once a good illumination and permit the use of the
Sight Indicator for revealing the gaseous condition of the

258

MINE GASES AND EXPLOSIONS

mine air. The indicator is shown in position in the lamp,
Fig. 36, but will be described later (Art. 204). This lamp
should be bonneted when used for general work; the un-
bonneted lamp, Fig. 36, is adapted to the work of testing
for gas. Both as a working and a testing lamp it gives ex-
cellent results. With two gauzes the bonneted lamp will
withstand a current velocity of 2,000 feet per minute, while
with three gauzes it can safely be used in an explosive
current of 2,500 feet per minute. Its illuminating power
is .75 for a two-gauze, and .60 candle
power for a three-gauze lamp burning a
good quality of sperm or colza oil.

The advantage derived from the use of
this lamp is the increased illumination,
freedom from smoking and the conse-
quent bedimming of the glass and ob-
struction of the gauze. With the indica-
tor in the lamp the slightest change in the
gaseous condition of the air is made
known quickly by the bright incandes-
cence of the looped wires shown above
the flame. These wires are called the
percentage wires, and show the exact
percentage of gas present in the air at the
moment and place of exposure. This
indication being made on the normal working flame of the
lamp, without its being necessary to draw down the flame,
is a sight indication that is always present; hence, the use
of this lamp avoids the danger arising from any lack of judg-
ment on the part of the man in charge of the lamp as to
whether a test is necessary, and his disposition to assume
that a place is clear of gas, which has been the cause
of many fatal accidents.

Fig. 36

Beard Deputy
Lamp

THE MUESELER LAMP

259

167. The Mueseler Lamp. — This lamp in its simplest
form consists of an ordinary Clanny lamp, in which is
inserted a conical sheet-iron chimney. There are two gen-
eral types of the Mueseler lamp, known as the EngHsh
Mueseler, Fig. 37, and the Belgian Mueseler, Fig. 38.
These differ only in the dimensions of their metal chimneys.

View Section

Fig. 37. — English Mueseler Lamp

The English chimney is broader and shorter and its bell-
mouth wider than that of the Belgian lamp, in which, at
times, the mouth is made straight instead of flaring, as
shown in Fig. 38.

In each of these lamps the air enters, passing through the
lower portion of the gauze above the glass chimney and
descending to the flame; the burnt air and gases pass

260 MINE GASES AND EXPLOSIONS

upwards through the central tube or chimney and escape
through the upper portion of the gauze. The chief char-
acteristic of the Mueseler lamp is the security it presents
against the transmission of the flame due to an explosion
within the lamp. In this respect the lamp has perhaps no
superior. The force of the explosion is mainly spent
within the sheet-iron tube, and is exerted downwards,
owing to the conical shape of the chimney. The central
chimney produces a strong upward draft and gives this
lamp a higher illuminating power than the Clanny, but it
is still far inferior to the Marsaut in this respect, being
only from .30 to .40 candle power. In Belgium a royal
edict makes the legal lamp of the following dimensions
with respect to its chimney:

Millimeters Inches

Interior diameter at top of upper cone. ... 10 .39

at base of upper cone. . . 25 .98

" at base of expansion ... 30 1.18

Height of chimney (total) 117 4. 61

" ' ' expanded base 6 .24

" '' base of chimney above wick tube 22 .87
" " top of chimney above gauze

diaphragm 90 3 . 54

The tests of The Royal Accidents Commission proved that
the Belgian lamp constructed with the above dimensions
was much superior to the English Mueseler, whose central
chimney was generally shorter and wider and set higher in
the lamp. While the Belgian lamps tested by the com-
mission successfully withstood an explosive current hav-
ing a velocity of 2,857 feet per minute, the English lamps
tested at the same time failed in a current velocity of only
1,000 feet per minute.

(( (C

THE MUESELER LAMP

261

In the genuine Mueseler lamp the combustion chamber is
divided at the top of the glass chimney by a horizontal
diaphragm of wire gauze, its purpose being to prevent, as
far as possible, the flame of the burning gases in the lamp
ascending between the central chimney and the outer gauze
chimney, which would heat the gauze to a dangerous

View Section

Fig. 38. — Belgian Mueseler Lamp

degree. This horizontal gauze diaphragm is shown at e,
Fig. 37. It is evident that the Mueseler lamp, owing to
its construction, is more dependent on a uniform and un-
changing circulation in the lamp than perhaps any other
type of lamp. The reason for this is that the upper por-
tion of the space between the central chimney and the
outer gauze -becomes filled with gas that may be highly

262 MINE GASES AND EXPLOSIONS

explosive, especially on the addition of a little air. A
slight inclination of the lamp from the vertical, or a de-
flection of the air-current striking the lamp, may cause this
gas to enter the combustion chamber, or in certain cases
may even cause its ignition in the ga'uze cap outside of
the chimney, which would present a greater danger than
an explosion in a Davy or a Clanny lamp. Owing to the
same conditions the Mueseler lamp is easily extinguished
when it is inclined at a slight angle from the vertical
and requires careful handling, because the products of
the combustion, filling the upper portion of the lamp
are at once thrown down upon the flame of the lamp on
the slightest diversion of the uniform circulation.

As compared with the Marsaut lamp the Mueseler gives
but about two-thirds as much light; it will not withstand
the current velocity that a three-gauze Marsaut will
withstand; it is extremely sensitive to oblique air-cur-
rents or any inclination from the vertical, which may
cause the extinction of the light or render the lamp under
possible conditions more unsafe than a common Davy
or Clanny lamp.

SPECIAL SAFETY LAMPS

i68. There are a large number of lamps designed for
special purposes or making use of special means. Of the
former class may be mentioned the Pieler, the Chesneau,
the Stokes alcohol lamp, the Clowes hydrogen lamp,
and the Beard-Mackie lamps, all of which save the last-
named make use of special flames for the purpose of test-
ing for gas in mines; of the latter class of lamps the Wolf
lamp is a prominent type, being designed to burn a special
illuminant, and having beside other special features.

169. The Pieler Lamp. — This lamp (Fig. 39) was de-
signed to test for gas by means of the alcohol flame, since

THE PIELER LAMP

263

this flame has been found to be extremely sensitive to
the presence of gas. The oil vessel is constructed to burn
alcohol. As shown in the sectional view a cylindrical
hood or shade is arranged about the flame; the height
of the shade being such that the tip of an ordinary sized

View Section

Fig. 39.— The Pieler (Alcohol) Testing Lamp

alcohol flame will just reach the top of the shade when
no gas is present. In appearance the Pieler lamp re-
sembles a tall Davy. The gauze of the lamp is about
7i inches high in order to accommodate the reach of the
alcohol flame when gas is present. When the lamp has
no bonnet a fixed scale is attached to the lamp standards

264 MINE GASES AND EXPLOSIONS

and provided with narrow slots to observe and measure
the height of the flame cap. Each slot is marked as in
the figure to indicate the percentage of the gas. If the
lamp is bonneted, a glass window is inserted in the bon-
net and the same scale is marked on the glass.

Like all alcohol lamps the Pieler is very apt to be extin-
guished when making a test, this often occurring before
the test has been completed, which is a great annoyance
and makes this lamp impracticable for the use of fire
bosses when examining a mine. The lamp is only useful
for the detection of small percentages of gas, since anything
over 2 per cent, of gas in the air will cause this lamp
to fill with flame; the top of the metal shield corresponds
to 2 per cent, of gas. Owing to the large gauze area and
the increased danger of the transmission of flame, the
lamp requires careful handling and should only be in-
trusted to an experienced person, who should exercise
due care not to expose the lamp to a body of accumulated
gas. When making a test to determine the percentage of
gas in an air-current, care must be taken to protect the lamp
from the direct force of the current. Within the brass oil
vessel is placed an amount of cotton that will absorb and
retain the alcohol in case the lamp is overturned, but
when the cotton is sufficient for this purpose its absorptive
power is so strong as to interfere with the heights of flame
cap and the correct determination of the percentage of
gas present in the air. The oil vessel is closed tightly by
a screw plug and a thin leather washer, as shown in the
sectional view.

The Pieler lamp was designed by an Austrian mining
engineer whose name it bears; it has been most largely
used on the continent in Austria, Germany, Belgium, and
France. The lamp is unsafe when the velocity of the air-

THE CHESNEAU LAMP

265

current exceeds 750 feet per minute, unless carefully
screened, when it may withstand a current velocity of 900
feet per minute, provided the quantity of gas present in
the air is small.

170. The Chesneau Lamp. — ^This lamp hke the Pieler

Bonnet Removed Lamp and Chimney

Fig. 40. — The Chesneau (Alcohol) Testing Lamp

is an alcohol lamp, designed for the purpose of testing for
gas in mines; the lamp is much safer in gas than the
Pieler. The inventor, G. Chesneau, an eminent French
mining engineer, professor of Mining at the National School
of Mines, Paris, and secretary of the French Firedamp Com-
mission, has given much thought and study to the forma-

266 MINE OASES AND EXPLOSIONS

tion of flame caps in gaseous atmospheres as a means of
measuring the percentage of gas present. The experi-
ments of MM. Mallard and Le Chateher, members of the
same commission, first drew attention to the higher caps
given by the alcohol flame. The Chesneau lamp (Fig. 40)
differs from the Pieler in the manner in which the air is ad-
mitted into the lamp through the double-gauze openings
a at the bottom of the chimney, shown immediately above
the oil vessel on the right of the figure. When the bonnet
shown on the left is screwed to the lamp, the entering air
passes through the openings c before it reaches the gauze
a. Setting on top of the base ring that holds the gauze a
is a hollow sheet-metal cylinder that surrounds the flame
and corresponds to the metal shield in Fig. 39, acting with
the base ring of the upper gauze ^ as a shade, to the top of
which the tip of the flame is adjusted in pure air. The
main gauze g rests on the upper flange of the shield b, the
whole being held in place by the sheet-iron bonnet d. The
gauze in this lamp is a much finer mesh than the standard
Davy gauze, since it has 1,264 openings to the square inch
instead of 784. The bonnet d is provided with a window
of mica or isinglass, on each side of which is a white scale
graduated, the one to read percentages and the other
centimeters. Surrounding the bonnet is a sliding shield
s that assists in obtaining a closer reading of the scale,
as this shield can be set to the exact tip of the flame cap
and the reading then taken. The brass oil vessel contains
cotton, but in much less quantity than in the Pieler lamp,
so as to avoid the impairing of the formation of the flame
cap by the absorption of the alcohol to such an extent as
to impede its flow.

The Chesneau lamp has been found to withstand a
current velocity of 11 meters per second, or 2,160 feet per

THE STOKES ALCOHOL LAMP 267

minute, in an explosive mixture of gas and air. One
peculiar difference between this lamp and the Pieler
is the time required for each to assume a normal state or
condition of the flame, so that the flame caps will indicate
by their height the correct percentage of gas present.
When a lamp is exposed to an atmosphere containing a
high percentage of gaS; it heats rapidly and retains this
heat for some time after being withdrawn from the gas.
Owing to the volatile character of the alcohol burned in
these lamps, the temperature of the lamp is sufficient for a
considerable time thereafter to vaporize the spirit, pro-
ducing an artificial gaseous atmosphere within the gauze,
which increases the height of the flame cap and renders
the lamp practically useless for making an accurate test.
It is stated that while the Pieler lamp requires about 30
minutes to assume a normal state, the Chesneau lamp
regains a normal condition in 30 seconds, but this will
depend largely on conditions and the length of time the
lamp was exposed to gas, and the degree of heating. The
ready vaporization of the more volatile ifluminants renders
them unreUable for the purpose of testing for gas in mine
workings where the lamp is often necessarily exposed con-
tinuously to a gaseous atmosphere, and the consequent
heating of the lamp causes it to give indications higher
than the actual.

171. The Stokes Alcohol Lamp. — In this lamp Mr. A. H.
Stokes, inspector of mines for the Midland district, has
endeavored to supply an alcohol flame, as desired, in a lamp
burning ordinary sperm oil or colza. For this purpose he
chose the Ashworth-Hepplewhite-Gray lamp shown in
parts in Fig. 41. This lamp is identical with that already
described and illustrated in Fig. 34, except for a small
tube that passes up through the oil vessel of the lamp and

268

MINE GASES AND EXPLOSIONS

the arrangement of a screw thread 5n the bottom of the
lamp to receive and hold the small alcohol lamp a. This
alcohol lamp is thus detachable from the oil vessel h, and
the cover c is then screwed in its place to close the opening.
The lamp a is provided with a long neck that reaches to

Oil Vessel and Alcohol Lamp Bonnet Removed
Fig. 41. — ^The Stokes Testing Lamp

the level of the top of the wick tube of the oil vessel h
when screwed in place. The top of the tube through
which this long neck passes is closed automatically by the
stop 0 when the lamp is withdrawn; this stop is operated
by a spring, being pushed upwards by the lamp a as it is
screwed in place and forced back by the action of the

THE ASHWORTH TESTING LAMP

269

spring. A spiral groove causes the stop to swing to one
side as it rises, so as not to interfere with the alcohol flame.
The latter is ignited by the oil flame, which is then ex-
tinguished by drawing down the wick with the pricker
p, leaving the alcohol flame alone in the lamp. After
making the test the oil wick is again raised and ignited
and the alcohol flame withdrawn. When the small lamp
a is not in use it is protected by the cap or cover /, which
is screwed to the top of the
lamp. The oil lamp is shown
here with a flat wick.

Other attempts have been
made by Ashworth, Chesneau,
and others to convert the com-
mon types of oil-burning lamps
that were considered safe lamps
into testing lamps burning
alcohol; but owing to the ex-
treme sensitiveness of the al-
cohol flame, the volatile char-
acter of the fluid, and the
generally unfavorable -condi-
tions for testing in the mine,
these attempts have met with
but partial success.

172. The Ashworth Tester. —
This lamp has a purpose simi-
lar to that of the Stokes lamp
just described, being indeed
the earlier lamp. It is not,
however, as light and portable as the above lamp. It has
two vessels, as shown in Fig. 42, the upper one for oil
and the lower for alcohol, the neck of the latter passing

Fig. 42.

The Ashworth Tester,
Oil-Alcohol

270 MINE GASES AND EXPLOSIONS

up through the oil vessel. The lamp is a combined
Ashworth-Gray type, all the features of which have been
described as those of the A-H-G lamp, Fig. 32 (Art. 165).
The oil-wick tube stands up higher in the lamp than the
alcohol burner, and is utilized as a shade to screen the eye
from the body of the alcohol flame when observing a cap.

Bonnet Removed Oil Vessel and Gas Cylinder

Fig. 43. — The Clowes Hydrogen Lamp

173. The Clowes Hydrogen Lamp. — This lamp is shown
in parts in Fig. 43, a section of the oil vessel being shown
in Fig. 44. It consists of a short-pattern A-H-G lamp
(Fig. 32) into the oil vessel of which has been inserted
a fine copper tube having a capillary bore for the passage
of the hydrogen gas. This tube h (Fig. 44) extends from
the opening 0 on the side of the oil vessel up through the
vessel, and its upper end terminates at the side of the wick

THE CLOWES HYDROGEN LAMP

271

tube w even with its top. The conical nozzle of the
gas cylinder a (Fig. 43) fits into the opening o (Fig. 44)
and is held in place by a union screwed to the lamp,
making a gas-tight joint. The nipple n screws into the
neck of the oil vessel and holds in place both the wick
tube w and the collar c, to which is attached the scale s
(Fig. 43) for gauging the height of the flame. A flat wick
is used in this lamp and is raised and lowered by the
usual form of pricker.

In Fig. 43 the hydrogen cylinder a is shown as connected
to the side of the oil vessel v. If the valve in the lower

Fig. 44.— Section of Clowes Hydrogen Lamp
end of the cylinder be now opened by a key fitted at t,
hydrogen will flow from the cylinder, where it is compressed
to a pressure of 1,800 pounds per square inch, to the tip
of the tube h, where it is ignited by the oil flame when this
is burning. When putting the lamp together the cylinder
is first detached from the oil vessel and the latter screwed
into the base ring of the chimney. The hook or claw b
is then made to engage the prongs at c, after which the
final connection is made by a screw nipple at d. The

272 MWB GASES AND EXPLOSIONS

hydrogen cylinder a of this lamp has been tested by
hydraulic pressure to 3,000 pounds per square inch.

When making a test the manipulation of the hydrogen
flame is the same as that previously described in the case
of the alcohol flame of the Stokes lamp. The height of
the flame cap is measured by the scale s attached to a
ring c (Fig. 44) that fits over the neck of the oil vessel and
is held in place by the nipple of the wick tube. The lowest
bar of this scale (see Fig. 63) is even with the top of the
wick tube; the second bar determines the height of the
standard flame, .4 inch. The four bars above this indi-
cate respectively .5, 1, 2, and 3 per cent, of gas being
set at .9, 1.1, 1.4, and 2.3 inches respectively above the
top of the wick tube. At these heights each bar is exactly
.2 inch below the tip of the corresponding flame cap,
which causes the bar to appear as a black line across
the flame. The position of the bar is thus clearly dis-
cernible, but allowance must always be made of .2 inch
when observing the cap. Like the alcohol flame the
hydrogen flame must be carefully handled to avoid its
accidental extinction, though it is not as sensitive in
this respect as the flame of alcohol. Cylinders of different
capacity are furnished as desired, but the small pocket
cylinder a (Fig. 43) charged to 120 atmospheres, which
is the most usual charge, contains 1,080 cubic inches of
hydrogen and will maintain the standard hydrogen flame
a little over two hours, permitting 200 tests to be made.
When empty the small cylinder is recharged from a large
stock cylinder, which must be kept on hand. The weight
of the lamp, filled with oil and the cylinder complete,
ready for use, is 4 lb. 14 oz. brass, or 2 lb. 7 oz. aluminum.
The Clowes lamp will determine with certainty the pres-
ence of .5 per cent, of gas, but below this point the cap

THE BEARD MACKIE LAMPS

273

is hazy and uncertain in its outline, and the percentage
of gas must be estimated more or less roughly. The
hydrogen flame is used for determinations up to 3 per
cent., while the oil flame is used as usual for determin-
ations from 3 to 6 per cent. (Art. 213).

174. The Beard-Mackie Lamps.— These are lamps that
have been specially designed to hold the Beard-Mackie
sight indicator, and are in most cases adapted to its use.
Such are the Eloin-Marsaut lamp
designed by the author (Fig. 3G), the
specialA-H-G lamp designed by John
Davis & Son, Derby, England (Fig.
45), a special French model lamp
designed by Paul Renaud, Paris^
France, and others. These lamps
have, in general, a glass SJ inX 2f in.,
and are arranged to admit the air be-
low the flame, so as to secure a more
uniforjn condition within the lamp
and give an atmosphere that will rep-
resent accurately the gaseous condi-
tion of the air surrounding the lamp.
This is a most important point in designing a good testing
lamp, as otherwise the results obtained are erroneous, al-
• though the indications may themselves be extremely accu-
rate. This is one of the greatest faults of a bonneted testing
lamp; under many of the conditions common in mine
workings, the bonnet, by restricting the free circulation of
air through the lamp, prevents the condition within the
lamp from representing accurately that of the outside air.
The Beard-Mackie lamps aim to avoid this fault by estab-
lishing and maintaining in the lamp a strong upward
draft, while the necessary protection at the top of the

Fig, 45. — Beard-Mackie
Lamp (English Model)

274

MUSE GASES AND EXPLOSIONS

lamp is secured either by the multiple Marsaut gauzes or
the Ash worth shield (Fig. 32). The principle of the sight
indicatoi insures an accurate sight determination at all
times to within one-half of one per cent, and ranging
from .5 to 3 per cent., owing to the bright incandescence
of the six looped percentage wires, which indicate by
their successive incandescence 0.5, 1, 1.5, 2, 2.5, and 3 per
cent, of gas present in the air. The single straight wire
above the flame is the standard wire for setting the flame
to the proper height when the lamp is in pure air. The
lamp glass is provided with a black enameled strip that
furnishes a good background for observing the indicator.
The construction and use of the indicator will be ex-
plained more in detail later (Art. 204).

175. The Wolf Lamp. — The usual form of this lamp
for general mine work is shown in Fig. 47. On the
left is the lamp surmounted by its
combined glass and gauze chimney,
while on the right is the corrugated steel
bonnet firmly attached by the standards
to the ring by which it is screwed to
the lamp vessel. In the foreground is
shown detached from the lamp the spe-
cial friction igniter i, of which a detail
sketch is shown in Fig. 46. The igniter
is shown in position in the lamp in
Fig. 48. It consists of a box i, into
which is inserted from the top a small
Fig. 46.— Igniter De- rod or puU bar /. To the upper end of

tached from Lamp ^^^^ ^^^^ ^^ ^^^^^ ^^ ^^^ ^^^^^^ j.^^^^

is attached a thin ribbon of spring steel bent double;
this is the scraper by which the friction match is ignited.
The right arm of the scraper is provided with sharp teeth

THE WOLF LAMP

275

at its upper end, and when the rod / is pushed up these
teeth are pressed into the match ribbon m, which is
threaded upwards through the opening o. The match is
thus carried up into position for lighting. It is here
shown coiled on a hinged plate a, which is turned down
for its insertion. The match consists of a waxed paper

Lamp and Chimney Bonnet Removed

Fig. 47.— The Wolf (Naphtha-Benzine) Lamp

ribbon, containing in its folds small nubs of a fulminate,
about three to the inch. The spring holds the scraper
against the match ribbon and keeps it in place. When,
now, the pull bar / is drawn down quickly, the cap is
exploded by the teeth of the scraper and the wax paper
is ignited and burns till extinguished at the top of the box,
the momentary blaze kindling the lamp wick.
While there may be times when it would be an unques-

276

MINE GASES AND EXPLOSIONS

tionable advantage to be able to relight an extinguished
lamp, the means to this end should be such as do not invite
danger at another time. The particular danger in this
case arises from the kindling of a flame in an atmosphere
at times heavily charged with an explosive vapor, which

Fig. 48. — Detail Section of Oil Vessel of Wolf Lamp

may cause a flash of flame to pass through the gauze of the
lamp and ignite gas outside of the lamp. So volatile is
the naphtha burned in this lamp that but a few seconds are
required to produce a dangerous flash (Art. 187), especially
if the gauze of the lamp be dusty or the mine air laden
with gas and dust. The writer is not questioning the

THE WOLF LAMP 277

advantage of relighting a lamp in case of necessity, but
would emphasize the danger in a gaseous mine when the
temptation to extinguish and relight a lamp is thus placed
promiscuously in the hands of boys and irresponsible
miners. Again, it may chance that the same blow that
extinguished the lamp may have broken the glass or in-
jured the gauze, in which case the relighting of the lamp
would be a positive danger, of which the miner is wholly
unconscious.

The construction and arrangement of the various parts
of the oil vessel of this lamp are shown in detail in Fig. 48.
The lamp is constructed to burn naphtha (benzine). This
fluid is highly explosive; it vaporizes rapidly and requires
the utmost care and caution in handling, to avoid accidents
when filling the lamps. The body of the font is made of
sheet steel and is provided with an extra heavy brass plate
a, which forms the top of the vessel. The only opening into
the oil vessel beside that for the wick tube w is that closed
by the screw plug p, having the same thickness as the top
plate a; this plug is removed by a forked key inserted in
the two holes shown in the top of the plug. Owing to
the explosive character of the naphtha burned in this lamp,
it is necessary to fill the font first with a specially prepared
filling cotton cut in strips about an inch wide. About two-
thirds of an ounce of this cotton is used in a lamp at one
time, a cyUndrical cotton spreader c being inserted to hold
it in place and to form a well from which the surplus fluid
is drained after fiUing the lamp and before closing the
font. A leather washer is inserted under the plug to
prevent leakage. The wick in this lamp is held in a
sheath s that sUdes up and down within the wick tube w^
being operated by the screw on the end of the rod r, which
passes through the small collar shown attached to the

278 MINE GASES AND EXPLOSIONS

upper end of the sheath s. The rod r is itself incased in
a brass tube that passes through the oil vessel. A small
lid b closes the top of this tube, and when removed permits
the sheath s to be taken out for renewing the wick. Rest-
ing on the shoulder of the font and firmly attached to it
is a steel corrugated ring provided with openings o for
the admission of air to the lamp, as indicated by the
arrows, the air being deflected upwards and entering the
combustion chamber through the protected openings in
the gauze ring g. Resting above the corrugated ring o
to which it is firmly attached is the screw ring t, forming
the means of securing the bonnet, which likewise holds
in place the glass chimney h and the gauze above. As
shown in the figure, the glass chimney rests on a washer
that fits over a spring ring n for the purpose of making a
tight joint between the chimney and the lamp. This ring
has at times been inadvertently omitted in putting the
lamp together, the glass chimney then resting on top
of the gauze ring g, which might cause the lamp to fail
in gas. The igniter box i (Fig. 46) is inserted in a special
well hole prepared to receive it, being sunk into the body
of the font but closed to the oil chamber. Its position
is shown by the dotted fines in Fig. 48, the end of the
burned match being shown at m.

After placing fresh filling cotton in the lamp the latter
is filled with as much naphtha as the filHng cotton
will absorb. Only 70-degree naphtha must be used, and
this should be placed in the lamp by means of a special
filling apparatus consisting of a tank holding, say 20 gallons
of the fluid. One form of fiUing tank used is shown in
Fig. 49. A small rotary pump is used to fill the tank
through the pipe a; from this tank the fluid is forced into
the glass cylinders 6, of which there are three attached

THE WOLF LAMP

279

to the side of the tank. Each cyhnder holds sufficient
oil to fill one lamp. A glass gauge c shows the level of
the oil in the tank; dripping pans d are placed beneath
each filling cock.
Great care is necessary to keep both the wick and the

Fig. 49. — Tank for Filling Wolf Lamps with Naphtha

filling cotton free from oil and grease, and they therefore
require to be renewed from time to time that the fluid
absorbed by the filling cotton in the lamp will rise readily
to the flame and the illuminating power of the lamp be
not impaired. Only specially prepared cotton must be
used in the lamp. When the lamp is to be filled the screw

280 MINE GASES AND EXPLOSIONS

plug is removed by means of a forked key, and the lamp
held so that the nozzle e of the faucet reaches well down
into the lamp. When the faucet is now opened the con-
tents of the glass cylinder flows into the lamp and is
absorbed rapidly by the cotton till the latter has taken
up all it will hold. The flow is stopped automatically as
soon as any surplus fluid accumulates in the lamp vessel.
The faucet is then closed and the lamp removed, the glass
cylinder again filHng automatically upon the closing of
the faucet. The surplus oil is drained from the lamp and
the plug again screwed in its place, having a washer be-
neath.

The principal features of the Wolf lamp are the self-
lighting attachment, of which mention has been made;
the increased illuminating power of the naphtha, which is
rated in this lamp as being 1 -candle power when first
lighted, reducing to .8 towards the close of the shift; a
magnetic lock, which it is claimed cannot be opened out-
side of the lamp room where a strong magnet is required
to loosen the fastening. Like all closely bonneted lamps,
this lamp goes out when exposed to a body of sharp gas.

LOCKS FOR SAFETY LAMPS

176. One of the important features of a safety lamp is
the lock, which prevents the lamp being opened while it is
in the mine. Locks have been designed from time to
time with different purposes in view; some of these afford
protection only against the lamp being opened inadver-
tently; others prevent the lamp being opened without
detection by the lampman having the lamps in charge;
others are so arranged that the lamp cannot be opened
without its flame being extinguished by so doing; and

LOCKS FOR SAFETY LAMPS 281

in another class the lamps are locked in such a manner
that they cannot be opened excepi through the agency
of a strong electro-magnet, or a powerful air-pump which
cannot in general be found outside of the lamp room.

177. Requirements of Locks for Safety Lamps. — ^A chief
requirement is simplicity of construction and absolute
certainty of action. It is not sufficient that a lamp be
made secure against being opened inadvertently, because
all men are not honest. It is sometimes inconvenient and
is often considered inadvisable to construct a lamp in such
a manner that it cannot be opened and the light retained.
When everything is considered, that form of lock that is
simplest, most quickly adjusted, and will most certainly
reveal any attempt to open the lamp is the lock that best
meets the practical requirements in a mine. This seems
to be the case with the common lead-plug lock.

178. Kinds of Locks. — The screw holt or screw plug is a
very common form of lock in mines, where the conditions
with respect to gas are not such that rigid regulations have
been enforced. In many such mines mixed lights are used,
and it is a common thing for a miner to open his safety,
since he is using his naked lamp much of the time. This
form of lock is shown on the Davy and Clanny lamps in
Figs. 21 and 25. The screw bolt forming the lock has
either a square or a flattened end that can be turned by
either a square or a split key. When a key is not at hand,
the miner often improvises one by sphtting a nail; no
ingenuity is required to open this lock. The lock repre-
sents the first of the different classes of locks mentioned in
Art. 176.

The lead-plug lock represents those locks belonging to
the second class, and which cannot be opened in the mine
without detection when the lamp is returned to the lamp

282

MINE GASES AND EXPLOSIONS

house. This is the simplest form of lock in use, and on this
account is generally preferred by mine officials. Owing
to its possessing no mechanism, it offers less inducement
to men and boys of a curious turn
of mind, and is less frequently dis-
turbed than more intricate locks,
which always invite investigation,
'^ with no other purpose than a test

Fig. 50.-Oil Vessel Fit- ^^ ingenuity. There are different
ted with Lead-plug forms of this lock, one of which is
shown in Fig. 50, and consists of a
hasp attached by a hinge to the base ring a of the lamp
chimney. When the oil vessel v is screwed in place the
hasp closes over a lug fixed to its side and having a hole
c through which the lead plug is passed. A special ma-
chine is generally used to clamp the plug and this is fur-
nished with a special print or with the date if desired.

Fig. 51. — Improved Rivet Mold

In Fig. 51 is shown an improved form of rivet mold
made in three sections. The lower section a is fastened
to a bench; the two upper sections b and c are removed,
heated, and replaced, being held together by the force
of the spring s and the nut n. The melted lead is poured
into the top of section c and fills the holes, which are seen

LOCKS FOR SAFETY LAMPS

283

cut away, in the section. Allowing a moment for the metal
to cool, the handle d is swung back and forth to shear off
the rivets in section b from the surplus metal in section c.
The upper section c is prevented from rotating when the
handle is swung to and fro by a projection on the central
axis that fits into a groove in the section. The upper sec-
tions are now removed and the rivets fall out. A hot
mold is required to produce good rivets. The mold con-
tains about 20 holes.

The protector lock (Fig. 52) is so called because it pre-
vents the lamp to which it is attached being opened with-

FiG. 52. — Sectional View of Protector Lock

out extinguishing the light. In the figure the brass plate
c screwed into the base ring a carries the glass chimney b
and at its center is threaded to receive the muff or collar
m screwed over the round wick tube w attached to the
oil vessel v. The muff m forms the extinguisher; it is
provided at its lower end with two flanges /. The end of
the lock-bar I, shown in section at e, is the arc of a circle
and fits against the collar and prevents it from turning, by

284 MINE GASES AND EXPLOSIONS

engaging the rivet r fixed in the flanges of the collar. The
lock bar is inserted into the opening in the base ring at o,
from the inside, before the lamp is in place. To do this
the spring s, which is riveted to the under side of the bar,
is pushed up so as to slide into the opening. When the
lock is in this position, the flanges / of the collar m are
free to pass the end of the bar e and the rivet r can turn
freely. The collar m is first screwed on the wick tube w
and the lamp lighted. The Hghted lamp is then passed
up into the base ring a, the muff or collar m screwing into
the plate c, as shown in the figure. When all is tight the
lock bar I is pushed in till its end strikes the collar m, and
the spring s drops and holds it fast on the inside of the
lamp. If, now, the oil vessel be unscrewed, the lock bar
will prevent the collar from turning, and the wick tube
will screw out of the muff, the hght being certainly ex-
tinguished by the operation. The lamp shown in the
figure is arranged to burn benzine.

Other locks of this class are so arranged that the un-
screwing of the oil vessel from the lamp brings a hood or
extinguisher over the flame, which smothers the flame
completely before the top of the lamp can be removed.

The magnet lock, as its name impHes, is operated by a
powerful magnet at the lamp house or lamp station.
There are different forms of the lock; that shown in Fig.
53 is the form adopted in the Wolf lamp. In this figure
only the base ring a of the lamp is shown, with the two
poles N and S of the large magnet used to operate the
lock and open the lamp. When the two nubs on the base
ring are in contact with the poles of the large magnet, as
shown in the figure, the small poles h and c of the lamp
are powerfully magnetized, the magnetism passing through
the spring e magnetizes the pawl p, the point of which is

LOCKS FOR SAFETY LAMPS

285

then drawn towards the pole h, which throws the tooth p
of the pawl back within the lamp ring and releases the
lamp so that it may be unscrewed from the ring. When
the lamp is removed from the poles of the magnet, the

Fig. 53. — Showing the Operation of the Wolf Magnetic Lock

spring e acts to throw the tooth of the pawl forwards, so
that when the oil vessel of the lamp is again screwed into
the ring it is locked automatically.

Another form of magnet lock used by the American
Safety Lamp Co., in a lamp
that very much resembled the
Wolf lamp, is that shown in
Fig. 54. Here the oil vessel
V is locked in the base ring
a of the chimney by the steel
bolt p, which is forced up-
wards by the spring c. When
the plug of soft iron h is in
contact with the end of a mag-
netized bar, the bolt p is
drawn down and the lamp re-

irnnrmiKM jmlLulaC/ "'^^iyn^

Fig. 54
A. S. L. Co. Magnet Lock

leased SO that it may be unscrewed from the lamp ring a.

286

MINE GASES AND EXPLOSIONS

This lamp is constructed to burn benzine, the oil vessel
being filled with cotton as in the Wolf lamp (Art. 175).
The wick remains stationary in the tube /, while the flame
of this lamp is regulated by raising or lowering the sheath e
attached to this nut h, which is operated by the screw
at the upper end of the shaft g. The igniter is shown
on the left of the wick tube; it consists of a friction match

Opening the Lamp Cambrian Lamp

Fig. 55. — Showing Operation of the Air Lock

slipped down between the spring k and the feed screw s,
which is operated by a button underneath the oil vessel.
On the upper end of the feed screw is a sharp-toothed
wheel that strikes against the friction match and ignites it.
The air lock is a simple and efficient lock, consisting of
a bolt held in place by a spring. The bolt fits tightly in a
bore and is drawn back when desired by the vacuum

PHOTOMETRY OF SAFETY LAMPS 287

created by a strong ^ir pump in the lamp house. There
is practically nothing in this lock that will easily get out
of order, and in this respect it is superior to the magnet
lock. The lock and its operation are shown in Fig. 55;
c is the cylinder of the air pump, which is operated by a
foot treadle, as shown. The nozzle n of the pump is forced
into the hole a of the lamp, and the downward movement
of the treadle creates a vacuum that draws back the
bolt and allows the lamp to be unscrewed

PHOTOMETRY OF SAFETY LAMPS

179. Whatever contributes to increase or decrease the
illuminating power of the safety lamp may be considered
under the general head of the photometry of the lamp.
Many factors that modify the illuminating power of lamps
have been considered in connection with the details of
lamp construction in studying the different types of
lamps. Some of the lesser details relating to wicks,
wick tubes, prickers, or trimmers, etc., will be considered
here. The illuminating power of a lamp, however, will
depend chiefly on the photometric value of the illuminant,
together with the manner in which it is burned. This
portion of the subject will, therefore, include references
to the classification and structure of illuminating flames;
measurement of light; nature of illuminants; and lamp
details affecting the combustion and therefore the light.

180. Classification of Illuminating Flames. — Flames used
for illuminating purposes may be classified properly with
respect to the combustible that feeds them, which may be
solid, liquid, or gaseous; thus giving three kinds of illumi-
nating flames. These are candle flames, oil-fed flames and
gas-fed flames.

288 MINE GASES AND EXPLOSIONS

iSi. Nature and Persistence of Flames. — Since (Art. 121)
flame, as here understood, is the luminous vapor or gas pro-
duced by the combustion of the illuminant, it appears there
are in all candle flames three operations necessary to
produce the flame, namely, the melting of the solid matter,
the distillation of the resulting liquid to form gas, and the
combustion of the gas attended with the phenomenon of
flame. In all oil-fed flames the last two of these opera-
tions only are required to produce the flame; while all
gas-fed flames evidently require but one operation, the
combustion of the gas. These differences play an im-
portant part with respect to the persistence of the flame
or its resistance to extinction, and affect also, in some
instances, the illuminating power of the flame. For ex-
ample, in a candle flame the melted wax reaches the flame
at a higher temperature than the oil of an oil-fed flame,
and the gas is more readily distifled to feed the flame.
As a consequence the candle flame is less easily extinguished
than an oil-fed flame, provided the melted wax is not
chilled by a cold draft of air. Again, all wick-fed flames,
whether candle or oil flames, are less susceptible to ex-
tinction than gas-fed flames, for the reason that the gas
being distilled in the flame, they are not dependent on an
uninterrupted flow of gas through a tube, which may be
momentarily cut off by a fluctuation of the air. Also,
the gas distilled in a wick-fed flame has a higher tempera-
ture than the gas fed to a flame through a jet, making the
flame not only more persistent, but improving its illumina-
ting power.

182. Causes Producing Extinction of Flames. — The ex-
tinction of a lamp flame may be due to any one of the
following causes : (1) an interruption of the feed ; (2) the
dilution of the air about the flame with extinctive gases,

PHOTOMETRY OF SAFETY LAMPS 289

or, what is practically the same thing, the depletion of the
oxygen of the air, or an insufficient supply of air to support
the combustion of the flame; (3) the dispersion of the
burning gas or vapor forming the flame, caused by a
strong current of air, as when a flame is blown out by a
puff of wind.

The appearance of the flame in each of these cases is
more or less mo ified by the surrounding conditions. An
interruption of the feed causes a diminution of the flame
followed by its extinction if continued a sufficient length
of time. An insufficient supply of oxygen or the presence
of a sufficient proportion of extinctive gas produces the
same result. A disturbance of the air about the flame,
produced by a strong draft or current of air, causes a like
disturbance of the flame, which is plainly manifest.

Briefly stated the extinction of a lamp flame is directly
due to an interruption of the flow of the combustible to
the flame, or to such a depletion of the oxygen of the air
supporting the flame, or dilution of the atmosphere about
the flame with extinctive gases as to separate too widely
the individual centers of combustion. The heat produced
is then insufficient to maintain the required temperature
of the gases, and as a result the flame dies away, the direct
cause being the absorption of heat by the large proportion
of incombustible gases present in the air. What is true
of the entire flame is likewise true, but in less degree, of
a portion, particularly the outer portion, or the surface of
the flame. The character of the atmosphere surrounding
the flame, its composition and temperature, affect the
combustion and appreciably alter the luminosity of the
flame. It is this fact that causes such differences in the
illuminating powers of some safety lamps, the reason for
which is sometimes not readily apparent.

290 MINE GASES AND EXPLOSIONS

183. Standard Flame or Light Unit. — ^The unit adopted
for the measurement of light is the intensity of the hght
produced by the burning of a properly trimmed sperm
candle (6's) weighing six candles to the pound, and so
proportioned that its flame, ih a quiet atmosphere, will
consume exactly 120 grains of spermaceti per hour, the
intensity of the light at a unit's distance from its source
being the unit of measure. Such a candle is often called
a standard candle, and the intensity of its light a candle
power.

Candles are made from different materials derived
from the vegetable, animal, and mineral kingdoms, among
which are tallow, wax, paraffin, spermaceti, and other
products less familiar. The candles made by different
makers from the same raw materials possess varying candle
powers, according to the method employed to purify the
material. However, calling the candle power of a standard
sperm candle unity or 1, the relative values for other
candles may be taken roughly as follows :

Paraffin 76 Wax 92

Stearin 77 Spermaceti 1 . 00

Tallow 83 Paraffin, extra refined . 1 . 14

Some composite miner's candles exceed the illuminating
power of the standard sperm candle, but these do not burn
with uniform intensity as does the sperm candle.

184. The Photometer. — A variety of forms of apparatus
have been devised for measuring the relative intensities of
different sources of light by Rumford, Bunsen, Wheat-
stone, and others, but that of Bunsen perhaps combines
the greatest degree of simpHcity and accuracy for
common use.

PHOTOMETRY OF SAFETY LAMPS

291

The general arrangement of the Bunsen photometer is
shown in Fig. 56, where the lamp or other light to be tested
is fixed at A, while the standard candle is stationary at B.
A paper screen s is mounted on a suitable standard h, which
can be moved along a graduated bar in line with the two
lights. The index or arrow at the foot of the standard in-
dicates the position of the screen on the bar, which is so
graduated that when the screen is equally illuminated on
both sides by the lights at A and B the reading shows the

1 1 I riilHt 1 'I'MM'iii ijl

Fig. 56. — Bunsen's Photometer

candle power of the light at A in terms of the standard
candle at B.

In order to determine more readily the equality of the
illumination on the opposite sides of the screen, a small
spot the size of a silver dollar is made translucent with a
little melted wax or paraffin. When the illumination from
behind is less than that in front, the center appears as a
dark spot that gradually vanishes as the screen is pushed
nearer the light in the rear. At times there will be a slight
difference when the screen is viewed from opposite sides
and the mean of the two readings must be taken.

It is evident that when the screen is equally illumined on
both sides, in a position C midway between the two lights,
the intensities of the lights are equal or the candle power of
the light ^ is 1. Now, to determine the illuminating power

292 MINE GASES AND EXPLOSIONS

of a light referred to that of a standard candle as unity, or
the candle power x of any hght, use is made of the principle
that the illumination is directly proportional to the candle
power of the light and inversely as the square of the distance
from the source. Calling the candle power of the light at
A, X, and its distance from the screen a, the illumination of

X-

the side of the screen toward this light is -^. In like

^ a^

manner the illumination of the screen due to the standard
candle at a distance h is t^. For the equal illumination

X 1
of both sides of the screen -^=t^, and

'=(-:

(30)

By the above formula the graduation of the scale of the
photometer can be calculated from .1 to 100 candle power.

185. Illtiminants for Safety Lamps. — ^The only class of
illuminants that can be considered at present as adapted
for use in safety lamps are the oils, and from these should
be excluded those highly volatile petroleum spirits having
low flashing points that render them dangerous fluids to
have in or about the mine and the buildings forming the
surface plant.

Safety lamps have been designed to burn solid paraffin
very much as the solid wax or tallow is consumed in the
burning of a candle, but the restricted circulation of the
lamp so far reduced the activity of the combustion that
heat was lacking to melt the solid ingredients, and this form
of illuminant was reluctantly abandoned.

Attempts have been made to use acetylene gas in mine

PHOTOMETRY OF SAFETY LAMPS 293

lamps for the purpose of illumination, the lamp being
arranged to generate its own gas by the contact of water
with a carbide, generally barium carbide. The gas is
supposed to be generated only as fast as it is consumed,
this being accomplished by the automatic regulation of the
flow of water into the carbide chamber. In a mine lamp
designed by Mr. T. N. Thompson, Scranton, Pa., the
acetylene vessel was arranged to be used interchangeably
with a common oil vessel in the same lamp, as desired.
The acetylene vessel consisted of two separate shallow cups
or vessels, one above the other, the two being connected
by a small brass tube. The upper vessel contained the
water and the lower one the carbide, which rested on a
perforated false bottom, beneath which gas might accumu-
late in small quantity. In this lamp the flow of water
into the carbide chamber was intended to be regulated
automatically by the pressure of the gas. When the gas
was generated faster than it was consumed, the pressure
rose and shut off the flow of water; and when the pressure
fell more water was admitted. The gas was burned at a
fine jet, and produced a beautiful flame and a very steady
light of about 20 candle- power. The flame is not easily
extinguished, but the carbide is expensive and the gas
dangerous, and should never be used in a mine of any
description, much less a gaseous mine requiring the use
of safety lamps.

The oils used as illuminants in safety lamps are derived
from vegetable, animal, and mineral sources.

The principal vegetable oils are ra'pe and colza; these are
derived from the seed of a special variety of turnip, which
is largely cultivated for the purpose in Europe, and are
practically the same oil, the former being the mnter rapCy
while colza is the summer rape. The vegetable oils have

294 MINE CASES AND EXPLOSIONS

a tendency to incrust the wick in burning, and therefore
require more frequent snuffing to maintain a uniform stand-
ard of fight. To avoid or lessen this difficulty it is cus-
tomary to mix these oils with a proportion of petroleum
(coal oil), the proportion varying from one-third part
petroleum and one part rape or colza, to equal parts of
both. The addition of the petroleum generally increases
the illuminating power of the oil but creates a tendency
of the flame to smoke, which limits the proportion of
petroleum that can be added. These oils after being
pressed out of the rape- seed are purified by treatment with
sulphuric acid, which burns out the organic impurities of
the oil, the latter being then washed to remove the refuse
and the surplus acid.

The animal oils in common use are lard oil extracted
from the lard obtained by refining the fat of hogs; sperm
oil derived from the fat and the brain of the sperm whale;
whale oil derived from the blubber of whales; and seal oil
derived from the seal. AU but the first of these are often
called fish oils. Sperm and lard oils are very largely used
in safety lamps, both pure and mixed with petroleum, as
described above in reference to vegetable oils; seal, except
highly refined quafities, and whale oils possess a greater
tendency to smoke, for which reason they do not make a
good oil for the safety lamp. Most of the sperm and lard
oils sold for illuminating purposes have a greater or less
proportion of the cheaper petroleum spirits mixed with
them, and it is difficult to obtain always a reliable grade
of illuminatmg oil. One of the advantages of using sperm
or lard oil is the greater freedom from the incrusting of the
wick. Trouble of this kind in the use of these oils will
very largely determine the lack of purity of the oil. The
illuminating power of sperm or lard oil will generally be

PHOTOMETRY OF SAFETY LAMPS 295

found somewhat greater than that of vegetable oils^ but
much will here depend on the relative purity of the oils.
A fairly pure vegetable oil may have a much superior
illuminating power than a comparatively impure sperm or
lard oil.

The mineral oils are all included under the general term
pelroleum. The crude oil is derived from certain oil-bearing
strata, chiefly shales, sandstones, and limestones, by boring.
The formation of petroleum is closely associated with that
of coal; it is generally believed to be of organic origin,
and to have been the result of the decomposition of vege-
table and animal remains away from air, or to have been
distilled from coal or other bituminous matters at a high
temperature. It is often called rock oil, because it exudes
from the strata. It is composed of hydrogen and carbon,
and when the crude oil is heated there are distilled in order
certain vaporous hydrocarbons, which condense on coohng
and form oils of different degrees of inflammability; those
distilling below 300° F. are generally termed light or highly
volatile oils, while the products distilled between 300°
and 570° F. form the common burning oil known as kero-
sene or coal oil. That distilled above 570° F. when con-
densed forms the heavy lubricating oils, and contains
paraffin, which solidifies at 130° F. and is separated from
the remaining heavy oil. Of the light oils, gasoline is
distilled below 140° F.; naphtha or benzoline from 140°
to 230° F.; and benzine from 230° to 300° F. The vari-
ous products of this distillation are often spoken of as
refined petroleum. About 1870 one of these light and highly
inflammable oils, probably gasoline, was introduced into
mining practice under the name colzaline, which has misled
many to believe that this oil was a safe burning oil. Col-
zaline was first used in the Davy and Stephenson lamps,

296 UmB GASES AND EXPLOSIONS

fitted with a special oil vessel (Fig. 52); the lamps being
styled ''protector lamps." Since then other lamps have
been designed for burning naphtha, benzine, and similar
highly volatile and dangerous oils, but their use is depre-
cated. When such oils or spirits are used a specially
prepared filling cotton is first placed in the vessel of the
lamp to absorb the fluid, and all excess of fluid is drained
from the vessel before it is closed.

i86. Flashing Point of Oils. — The temperature at which
an oil gives off inflammable vapor that will ignite when a
flame is held near the surface of the oil is called the flashing
point of that oil. The comparative danger in the use of
different highly volatile oils is determined by their flashing
points, which should always be carefully ascertained for
each new supply of such oil to avoid mistakes that may
happen and to guard against adulteration with the lighter
oils. All vegetable and animal oils have flashing points
so high as to render them safe for all ordinary use in mine
practice, but mineral oils have much lower flashing points
and their use always requires caution in proportion as the
oil is more volatile. When kerosene or coal oil is used to
adulterate a vegetable or animal oil, its flashing point
should not be lower than 80° F.

For all practical purposes the flashing point of an oil
may be determined by what is called the open test, in which
a small test tube is fifled half full with the fluid to be tested
and inserted in a bed of sand contained in a suitable pan
or dish that may then be gradually heated by a lamp flame
or gas burner. The temperature of the .oil is determined
with a thermometer inserted in the liquid, and at intervals
the flashing of the vapor is tested by a flame applied to the
mouth of the tube. A few trials will determine with
sufficient accuracy the lowest temperature at which the

PHOTOMETRY OF SAFETY LAMPS 29?

vapor rising from the oil will flash. In testing oils with
low flashing points a water bath may be substituted for
the sand bath.

187. Comparison of Oils and Candles. — The photometric
value and rate of burning of different oils and different
makes and sizes of candles has been closely investigated
by Mr. A. H. Siokes, in a large number of carefully con-
ducted experiments, which show wide variations owing
not only to differences in composition but to the conditions
of burning the illuminant and particularly the form of
lamp in which the oils were burned. So slight is the dif-
ference in the photometric values of the illuminants them-
selves and so vastly more potent the 'conditions affecting
the combustion that it is quite evident that only in respect
to a few particulars can a just comparison be made of
these illuminants, and reliable data given concerning them.

In respect to candles, it is shown by the experiments
that the composite wax candles having plaited wicks, to
reduce the amount of snuffing necessary, do not have the
candle power of a properly snuffed tallow candle, which
in a few instances was practically double that of the stand-
ard sperm candle. The sperm candle, however, is the se-
lected standard of light, because the illuminant is simple
while the others are more complex. The weight of material
burned per unit of time determines the intensity of the light.
The wax composite candles tested burned on the average
145 grains of wax per hour, with an average yield of 1.44
candle power. The tallow candles burned an average of
190 grains of tallow per hour, with an average yield of
1.64 candle power. Practically the wax candles are more
serviceable, because they require less attention than the
tallow.

In respect to oils, a restricted circulation of air in the

298 MINE GASES AND EXPLOSIONS

lamp has less effect to reduce the illumination when burn-
ing either vegetable or animal oil than when mineral oil
is used; the latter requiring a larger supply of oxygen for
their proper consumption than the former. When colza
oil was burned in a single-gauze lamp the candle power was
.57, which was reduced in a double-gauze Marsaut lamp
to .52, or say 9 per cent. When a mixture of colza and
petroleum was burned in the same lamps the reduction in
candle power was from .84 to .72, or say 14 per cent. When
petroleum was burned alone in the same lamps the reduc-
tion in candle power was from .96 to .63, or say 33 per cent.
Thus, the effect of mixing petroleum in proper proportion
with vegetable or animal oil is to reduce the incrusting of
the wick, and increase the illumination, but these results are
less pronounced in a closely bonneted lamp. In general, it
may be stated that the addition of a lighter oil to vegetable
or animal oil will increase the rate of burning. For ex-
ample, rape oil was consumed in a double-gauze Marsaut
lamp at the rate of 55 grains per hour; or 2 fluid ounces in
17 hr. 35 min. A mixture containing three parts rape and
one part petroleum was consumed in the same lamp at the
rate of 72 grains per hour, while a mixture of two parts
rape and one part petroleum was burned at the rate of
77 grains per hour.

The attention given the matter of illuminants for safety
lamps by the Royal Accidents in Mines Commission in
England is worthy of the highest commendation; and
their conclusions, based on an extensive series of experi-
ments, are practical and safe. The findings of the com-
mission in regard to the nature and the adaptation of dif-
ferent illuminants to mining conditions are in full accord
with what has been already stated. The experiments of
the commission were conducted with particular regard

PHOTOMETRY OF SAFETY LAMPS 299

to the adverse conditions in gaseous and dusty mines, and
the results obtained led the commission to unhesitatingly
deplore the use in these mines of ''petroleum or paraffin
oils of such flashing points as might warrant their use,
under normal conditions, as safe illuminants for miners'
lamps." It is the adverse conditions that make the pres-
ence of a highly volatile oil in a safety lamp objectionable
and dangerous. The danger is also greatly increased by
the presence of an igniter (Art 175). The volatile spirit
vaporizing from the wick of an extinguished lamp creates
in a brief period of time an explosive atmosphere within
the lamp, which causes a flash when the lamp is relighted
with the igniter. This flashing of the lamp is dangerous
in proportion to the condition of the gauze with respect
to dust and the gaseous condition of the mine air. The
relighting of an extinguished lamp always assumes a risk
that should only be taken when the alternative presents
an equal or even greater danger.

The results of the experiments of the commission re-
ferred to above may be briefly summarized as follows:
(1) Refined rape oil of good quality maintains, for a brief
period only, uniformity- in the height of the flame and
intensity of illumination, but the wick chars quickly and
must be trimmed often. (2) Good clear seal oil is much
superior to the refined vegetable oils, rape and colza, with
respect to the maintenance of a fairly uniform height of
flame and candle power without recourse to trimming the
wick. In one experiment, using a two-gauze Marsaut
lamp burning a good quality of seal oil in a still atmos-
phere, the lamp flame being left untouched, the height
of the flame continued constant for two hours after light-
ing, and fell from 1 inch to .7 inch during a further period
of five hours following. (3) Refined vegetable oil mixed

300 MINE GASES AND EXPLOSIONS

with petroleum having a flashing point of 80° F., in the
proportion of two volumes of the former to one volume of
the latter, showed an improvement in the maintenance of a
uniform height of flame, with practically the same candle
power as the unadulterated vegetable oil. When the
mixture, however, contained equal volumes of the vege-
table oil and petroleum there was a further improvement
in the maintenance of the flame and an increase of candle
power. The same results were obtained by the addition
of petroleum to seal oil. In each case the adulteration
caused a considerable increase in the rapidity of con-
sumption of oil and wick; the lamp became hotter and
the wick took fire at the slot in the wick tube where the
pricker is inserted to raise the wick.

The commission arrived at the following conclusions as
a result of these experiments: A seal oil of good average
quality is decidedly superior in general burning quahties,
namely, the duration of uniformity in the height of flame,
to the refined vegetable oils, rape and colza. The admix-
ture to either of these oils, but especially to seal oil, of
petroleum having a flashing point not lower than 80° F.,
in the proportion of not more than one volume of petro-
leum to two volumes of vegetable or animal oil, produces
an illuminant considerably superior to either of the un-
adulterated vegetable or animal oils. Further, the experi-
ments afforded no evidence that when petroleum and
other oils were so mixed they were consumed in unequal
proportions at any time during the burning of the lamp.
What is said of seal oil in the report of the commission
is likewise true to an even greater extent of the best
grades of sperm and lard oil. For mine use it is important
to secure the pure unadulterated sperm or lard oil, and
make the addition of the kerosene or coal oil having a

THE SMOKE TEST 301

flashing point not less than 80° F., at the mine, in the pro-
portion of one volume of coal oil to two volumes of the
animal oil.

i88. The Smoke Test. — The burning of a poor grade of
oil in the lamps in a mine is not only unhealthy and in
some cases unsafe, but often an intolerable nuisance. In
general it is easy to detect on a single visit to a mine the
burning of an inferior grade of oil by the peculiar oily
soot deposited in the nostrils and on the skin. On
quickly learns to discriminate between the oily filth of an
impure illuminant and the legitimate dirt of a coal mine,
when his attention has once been drawn to the matter.
In some districts the miners have a bad habit of burning
a considerable proportion of the heavy lubricating oil used
on the mine cars, in their open lamps, and it is often quite
impossible to stop the practice. Some drivers will often
burn nothing but coal oil in their lamps. They do this
because the flame of coal oil is not so readily blown out,
and a driver never wants to ''get in the dark.''

Many of the oils offered on the market and sold as mine
illuminating oils are wholly unfit for the purpose. The
opinion, in some cases an honest one, is often expressed
that an oil that is too poor for other use will still make a
fair oil for mine lamps. It is sometimes a revelation to
men to be told that the best grade of oil is required for a
mine illuminant. So great has been the annoyance not
to say danger growing out of the adulteration of mine oils
that State departments have been forced to adopt meas-
ures to protect the health of mine workers. For practical
purposes, it has been found that the chemical analysis of
an oil to determine its degree of purity was too elaborate
for general use and a more ready means had to be sought
that could be employed at the mine and that would

302

MINE GASES AND EXPLOSIONS

demonstrate in a practical manner the relative merits of
oils with respect to the contamination of the mine air.
Naturally, recom-se was had to what has become known
as the smoke test, and for the purpose of making this test,
the apparatus shown in Fig. 57 has been used in Ohio and
elsewhere. This consists of a rough wooden box about 2
feet long, 1 foot high, and from 6 to 8 inches deep. As

Fig. 57.^A Practical Smoke Test for Illuminating Oils

shown in the figure, it is divided into four compartments,
although a larger box can be used giving a greater number
of divisions. In the center, above each compartment,
holes IJ inches in diameter are bored, and into each hole
is fitted a piece of tin rolled in the shape of a funnel to
serve as a mantle or hood for collecting the smoke of the
lamp placed beneath the funnel in each compartment.
The smoke produced by the lamps is thus directed upwards
into the tall glass chimneys placed loosely above each hole.

WICKS AND WICK TUBES 303

The quantity of smoke produced by each sample of oil
burned is closely observed against the white screen placed
behind the chimneys; this quantity is gauged roughly by
the eye. One of the lamps is always filled with pure oil
whose standard has been previously determined, and by
comparison with this the relative purity of the other oils
is judged. If the difference observed in any case is small,
the glass door covering the front of the compartment
should be slid down to reduce the volume of air, which
then enters the box through the J-inch hole at the back
of the box. In making this test it is necessary to use the
same kind of lamp in each compartment; each lamp having
the wick prepared with the same number of strands and
in the same manner, to obtain uniformity of conditions.
A new wick should be used in every case, and the lamp
should be burned a sufficient length of time to burn off
the top wicking and insure uniformity in this respect, before
being placed in the box:

189. Wicks and Wick Tubes for Safety Lamps. — The
two general forms of lamp wicks used in safety lamps are
the round and the fiat wicks; the circular or argand type
of wick has been" employed but to a limited extent only
The round wick is generally the favorite, especially in
lamps designed for testing for gas, because this form gives
greater constancy of flame and more uniform conditions
with respect to the burning of the wick. A flat wick is
prone to cause a lack of uniformity in combustion through-
out the flame; the center of the wick often consumes more
rapidly than the corners, which are charred, causing a
tendency to flaring and a smoky condition in the edges of
the flame. The round wick produces a cone of flame in
which the condition is everywhere uniform.

The wick of a lamp is, so to speak, the conveyancer of

304 MINE GASES AND EXPLOSIONS

the oil to the flame, the flow of the oil being induced by the
capillarity of the wick. Flat wicks are loosely woven or
plaited, the warp forming the chief strands of the wick,
while the woof or cross thread by which they are sewed to-
gether is a fine thread that will not interfere with the upward
flow of the oil. Round wicks are generally made up from
ball wickings; the threads forming the strand of the ball
being simply laid parallel, five or six threads forming the
strand. A length of about 2 feet is cut from the ball and
folded to make a wick of, say five strands about 5 inches
in length. This is bound at the end by one or two threads
drawn from the wick; the ends of these threads are easily
blown through the wick tube and serve to draw the wick
into the tube, after which they are burned off. The wick
must fit loosely in the tube; if too tight, a few threads
should be carefully drawn out of the wick, taking care not
to tangle the other threads. A flat wick is generally made
a very httle broader than the tube; the wick is J inch wide
and the top of the tube ^ inch. This tube should always
be made corrugated on one side, to provide for the free
circulation of the oil in the wick. Most flat wick tubes
have a small air tube soldered on one side to give, as it is
claimed, vent to the air in the oil vessel.

Lamp wicks should never be used when they have be-
come gummed or clogged with old oil, as the lamp will
then fail to burn properly. A short wick frequently re-
newed will be the means of greatly improving the fight.
The flame in a safety lamp should be set high enough in
the lamp to reduce to a minimum the shadow thrown on
the ground by the lamp. The top of the wick tube should
not be less than ^ inch above the bottom of the glass.

The pricker of a safety lamp is an important item. The
usual form in use is the small upright rod extending through

ILLUMINATING POWER OF SAFETY LAMPS 305

the oil vessel. This pricker affords no adequate means
of properly cleansing the wick from the crusts of carbon-
ized material that form on the wick. The incrusting of
the wick is due largely to impurities in the oil; it is also
increased by incomplete combustion, which may be due
to a variety of causes connected with the construction of
the lamp, and even the condition of the mine air. Some
men become quite expert in cleaning the wick with the
pricker and others are almost certain to lose their light
in the attempt to improve its condition. If all that were
required were the raising and lowering of the wick, other
arrangements could easily be introduced that would per-
form that work more easily and perfectly than the pricker,
but the wick must be cleaned as well as moved up and
down, and the pricker is thus far the only device offered
that will do this, however imperfectly.

190. Illuminating Power of Different Safety Lamps. —
Aside from the photometric value of the illuminant burned
in the lamp, every lamp has an illuminating power peculiar
to its construction. In lamps in which the flame is sur-
rounded by wire gauze, as in the Davy lamp, the illumi-
nating power is much reduced, because the light is cut off
by the wires of the gauze. In lamps of the Clanny type
where the flame is surrounded by a glass chimney, the
illuminating power is greatly improved but still impaired
by other features of lamp construction that affect the
circulation of the air entering and passing through the
lamp and particularly the supply of oxygen to the flame.
In some lamps, by virtue of the interior arrangement or
the restriction of the discharge at the top of the lamp or
both of these combined, much of the vitiated air in the
upper part of the lamp finds its way into the combustion
chamber. This dilution of the air in the combustion cham-

306

MINE GASES AND EXPLOSIONS

ber by the extinctive gases from the top of the lamp
impairs the combustion of the oil and reduces the lumi-
nosity of the flame. The reason of the comparatively low
candle power of the Mueseler lamp is probably that
much of the air after passing over the flame fails to
pass up the central chimney directly as it should, and is
wafted back into the combustion chamber, thus diluting
the entering air, or blocking the intake through which it

Table 24
average illuminating power of different safety lamps

Lamp

Candle Power

Davy (common)

Davy (Jack)

Davy (in case)

Stephenson, "Geordie"

Clanny (improved), various types.

Evan Thomas, No. 7

Marsaut (two-gauze)

Marsaut (three-gauze)

Gray.

Ashworth, No. 4

Ashworth-Hepplewhite-Gray

Ash worth-Hepple white-Gray (recent)

Beard, Eloin-Marsaut (two-gauze) sperm oil . .
Beard, Eloin-Marsaut (three-gauze), sperm oil.

Mueseler (Belgian)

Mueseler (English)

Wolf, naphtha (benzine); when first lighted . .
'* " " at end of shift

.15
.08
.16
.10

.25 to .50
.40
.60
.45
.33
.55
.65
.79
.75
.60

. 35, reduces gradually
.30
1.00
.80

attempts to pass. In either case the energy of the com-
bustion in the flame is impaired from a lack of oxygen.

From the above facts it is readily observed that any one
type of lamp may show a wide variation in candle power,
according to the quality and kind of illuminating oil
burned and certain slight modifications in construction,
which affect the combustion. For example, the different
types of Davy lamps, examined by the British Accidents

ILLUMINATING POWER OF SAFETY LAMPS 307

in Mines Commission, burning different oils gave values
ranging from .07 to .22 candle power, while a fair average
value for the common Davy lamp is between .15 and .16
candle power. Table 24 gives the average candle power
of the different types of lamps burning a good quality of
vegetable oil, except where another illuminant is specified.

CHAPTER VII
TESTING FOR GAS

GAS INDICATORS

191. Under this heading are included all such means and
appliances as may be used to determine the percentage of
marsh gas (methane) present in the air, other than the
ordinary flame test by which the percentage of gas is
estimated from the height of the flame cap visible above
the lamp flame.

192. Monnier, Coquillion, Maurice. — A number of in-
genious devices have been tried at different times having
for their purpose the indication of the presence of gas in
mine air, but with few exceptions all have proved im-
practicable for common use in the mine. Monnier, Coquil-
lion, and Maurice each constructed indicators for determin-
ing the relative volume of inflammable gas in samples of
air tested. These devices all depended on burning out the
gas from a carefully measured volume of gas and air, and
afterwards measuring the remaining volume of air and
carbon dioxide at the same temperature and pressure.
In each case the combustion was effected by means of a
fine platinum wire fused into a glass tube that could be
filled with the air to be tested. Having noted the tem-
perature and pressure of the contained air by a suitably
arranged thermometer, and barometer or pressure gauge, the

308

GAS INDICATORS 309

platinum wire was brought to a white heat for a few seconds
by passing through it a current from a battery or a mag-
neto-electric machine, thereby consuming the inflammable
gas and producing in its place carbon dioxide and water
vapor, which vapor was condensed when the temperature
again became normal. A comparison of the resulting
volume of the residuum air with the results of previous
experiments when the proportion of gas in the air was
known gave the percentage of gas present in the sample
of air tested.

193. Aitken. — A similar device constructed by Mr. John
Aitken (1880) determined the percentage of gas present
from the decrease of pressure caused by the consumption
of the gas.

194. Ansell, Libin.— The indicators of MM. Ansell (1865)
and Libin (1883) depended on the principle of the diffu-
sion of gases. In these devices two closed spaces of equal
volume, the one filled with air and the other with air and
gas at equal temperature and pressure, were separated by
a thin porous partition. As diffusion proceeded the pres-
sure in the space filled with pure air increased till it at-
tained a maximum and then gradually declined till the
original pressure was reached; the maximum increase of
pressure has been found to be nearly proportional to the
percentage of gas present in the air tested.

195. Aitken, Smith. — Another class of indicators con-
structed by Aitken and Smith, respectively, depended on
the heating effect of the gas. Mr. Aitken in the construc-
tion of his second indicator employed two thermometers,
which he placed side by side in a tube arranged so that the
air to be tested could be drawn through the tube. The
bulb of one of the thermometers was coated with a thin
covering of a mixture of plaster of Paris and platinum

310 MINE GASES AND EXPLOSIONS

black, which induced chemical action and caused the com-
bustion of the gas. The heat due to the combustion
raised the temperature and caused the thermometer having
its bulb coated to give a higher reading than the other
thermometer. The difference between the readings of the
two thermometers was assumed to be a fair index of the
percentage of gas present in the air tested. Other causes,
however, might operate to increase or decrease this dif-
ference, which would render the indications unreliable. It
was further found necessary in order to determine small
percentages of gas with this indicator to raise the tem-
perature of the air being tested to that of boiling water,
which made the device of no practical value in the mines.

The indicator constructed by Dr. Angus Smith was
also of no practical value. It consisted of a strong glass
tube closed at one end and fitted with an air-tight piston.
When the tube was filled with air containing not less than
5 per cent, of gas and the piston was pushed down quickly,
sufficient heat would be generated by the compression of
the air to fire the gas and cause a flash. When less than
this percentage of gas was present, however, it was found
necessary to place a small quantity of platinum black in
the bottom of the tube to cause the ignition of the gas,
but even then no flash was obtained when less than 2.5
per cent, of gas was present. This percentage of gas
was more easily found by means of the ordinary flame
test, however, and in less time.

196. The Liveing Indicator. — The indicator designed by
Mr. E. H. T. Liveing proved of greater practical value and
has been used to a considerable extent in mines. Like
the Aitken and Smith indicators just described, it de-
pended on the heating effect of the gas present in the air
being tested, but the intensity of this effect was meas-

THE LIVEING INDICATOR 311

ured by the relative brilliancy of two platinum wires of
equal electrical resistance and heated to incandescence by
an electrical current. The apparatus, except the lower
portion of the box, which contained the magneto-electric
machine for generating the current, is shown in section
in Fig. 58. It consisted of two platinum coils, one of which

«S .« eo o»

Fig. 58. — Section of the Liveing Gas Indicator

m was inclosed in a sealed tube a containing pure air
while the other n was contained in a similar tube 6, pro-
vided with gauze-protected openings for the admission of
the gas-laden air to be tested. These small tubes a and h
were placed opposite each other in a larger tube H, a
portion of which was cut away from c to c^ to permit of the
movement of the sliding section T carrying the screen s.
This telescopic sliding section T of the tube was provided
with a glass window w for making observations. The ends
of the two small tubes a and h facing each other were
closed with glass plates g that permitted the rays of light
from the incandescent coils m and n to fall upon the two
inclined faces of the wedge-shaped screen s between them.
By applying the mouth to the mouthpiece p the air to
be tested was drawn into the tube H through an opening
Oj filling the tube h having the openings covered with
wire gauze. By turning a crank on the side of the box
the magneto-electric machine was made to generate a
current, which passed through the two coils m and w,
heating them to the same intensity if the air in the box
contained no gas. If gas was present, however, its com-

312 MIXE GASES AND EXPLOSIONS

bustion in contact with the coil n increased the tempera-
ture and the brilliancy of the incandescent wire^ and as a
result the face of the screen s toward n was brighter than
that toward m. The sUding tube T is now moved to the
left till both these faces are equally illuminated, when the
reading of the end of the sliding section on the graduated
scale shown at the left indicates the percentage of gas
present in the air tested. That this method affords an
accurate means of determining very small percentages of
gas, provided the observer is able to correctly judge of the
equal illumination of the two faces of the screen, is shown
by the following rapid increase of the illuminating power
of the incandescent platinum coil: namely, pure air==l;
air containing gas: .25 per cent. 1.23; .50 per cent. 1.52;
1 per cent. 2.24; 1.5 per cent. 3.10; 2 per cent. 4.28;
2.5 per cent. 6.00; 3 per cent. 8.55; 3.5 per cent. 12.70;
4 per cent. 19.30; 4.5 per cent. 31.00; 5 per cent. 51.40.
There are some sources of error in the use of this machine,
which at the first were unsuspected. The relative brillianc}^
of the two coils forms a true index of the degree of inflam-
mability of the gas-laden air, but the inflammability in-
creases from zero as the proportion of gas increases till
the latter forms 9.46 per cent, of the mixture, when it
reaches a maximum; beyond this point the inflammabihty
of the mixture decreases as the percentage of gas increases
(Art. 88). Owing to this fact, it is clear the indications of
the machine represent, each, two conditions with respect
to the proportion of gas in the air, and these conditions
are far from being like dangerous. A lamp flame would
reveal at once which of the two conditions was the one
that existed in the air tested, because of the increasing
extinctive effect of the higher percentages of the gas
Again, it has been found that the electrical resistance of

OTHER INDICATORS 313

platinum wire on continued exposure to the action of gas
changes so rapidly as to render the results quite uncertain
after the first few tests made; besides there is always the
imminent danger of the electrical apparatus causing the
ignition of the gas from the sparking of the contacts. For
these reasons the device is not all that is required of a gas
indicator for mine use.

197. The Forbes Indicator. — ^Numerous other forms of
indicators have been devised, some correct in principle
but not of practical application to mine work, or too ex-
pensive, weighty, or cumbersome; while others consume
too much time or require too careful manipulation to be of
general use. The most ingenious of these perhaps was
the indicator invented by Prof. George Forbes, which
depended on the difference in the length of the sound
waves in gases or air of different densities, as compared
with that of the same note in pure air. In this device a
tuning fork of 512 vibrations per second was sounded in
the mouth of a brass tube 1 inch in diameter and about 6
inches long and fitted with a tight piston whose position
in the tube was indicated by the index of a graduated disk
3 inches in diameter. The piston was first set so as to
produce the greatest resonance when the fork was sounded
and the tube filled with pure air. The tube was then
filled with the air to be tested and the movement of the
piston necessary to produce a maximum resonance indi-
cates the percentage of gas present. The temperature at
each observation was noted by the attached thermometer,
and the necessary correction made for any change of
density due to the temperature of the air.

198. The Garforth Appliance. — The device used by W.
E, Garforth for collecting gas from cavities in the roof,
where it would be difficult or inconvenient and perhaps

314 MINE GASES AND EXPLOSIONS

unsafe to introduce a lamp, consisted of a simple hand
bulb of India rubber provided with a long neck that could
be inserted upwards through a tube extending completely
through the oil vessel of a safety lamp, so as to discharge
the contents of the bulb drawn from the roof into the
combustion chamber of the lamp close to the lamp flame.
This device could hardly be styled an indicator as it has
been called. It embodies no new principle.

199. Other Devices. — Devices have been proposed by
which a safety lamp was to be provided with some appliance,
such as a double strip of two metals of unequal expansion,
and that would by its movement ring a small bell attached
to the lamp whenever the heat of the burning gas reached
a certain point. Another arrangement closed certain air
vents in the lamp, which was promptly extinguished when-
ever gas fired in the lamp. Other equally ingenious but
unreliable devices have been proposed, but none of these
have seemed to appeal to the practical mining man, and
as a consequence have failed of general adoption.

200. Signal Apparatus. — Still another form of gas in-
dicator is that designed to transmit a signal of warning
to the superintendent's office, on the surface, when the
presence of gas in sufficient quantity set the device in
operation at different points in the mine where the indica-
tors were placed. Several forms of such apparatus have
been tried at different times and in different countries,
only to receive the condemnation of practical men, for
I he excellent reason that all such indicators can only
reveal the presence of gas at some isolated point, which
under the ever-changing condition of the mine and the ven-
tilating current is almost certain not to be the point of
greatest danger. All the systems of this kind thus far pro-
posed would at the best give a very tardy warning, and in

THE SHAW SIGNALING SYSTEM 316

every case the action has depended on some delicate
means — for example, the ascensional force of the gas act-
ing on a delicate balance located in a position near the
roof — as in the apparatus proposed by the French en-
gineer, Jean Molas. This was likewise the principle of
action of the system devised by an American engineer,
Mr. G. H. Carlton. To the same class belong the proposed
methods of Messrs. George Duggan, Henry Reece, Chaloner,
and Delia Bella, all of whom presented their plans to the
Royal Accidents Commission of England in 1880. Another
plan hkewise proposed by an American and possessing a
greater element of danger consists in transmitting through
the workings a current from a Ruhmkorff induction coil on
the surface. The wiring was arranged with numerous
breaks at different points in the mine where gas might
accumulate, each being protected by a covering of wire
gauze, which while it admitted the gas to the sparking
wire was expected to prevent the ignition of the gas
outside of the gauze. It is hard to understand how such
a dangerous contrivance could have emanated from the
brain of any practical man.

201. Shaw's Signaling System. — ^An equally impracticable
though less dangerous plan was that proposed and brought
prominently before the mining public in 1887 by Mr.
Thomas M. Shaw, a mining engineer of Ohio. Mr. Shaw's
experience in the determination and measurement of gases
in the laboratory enabled him to devise an excellent ma-
chine for determining with great accuracy the percentage
of certain gases when mixed with air. This machine after-
ward became known as the Shaw Gas Machine and will
be described later. Mr. Shaw's scheme, however, to utilize
this machine in connection with an elaborate system of
pipes extending to different points in the mine for the

316 MINE GASES AND EXPLOSIONS

purpose of drawing the gas from these points to the surface
and passing it continuously through the machine to de-
termine its percentage composition was highly impractic-
able for various reasons. As previously stated, such in-
dications would be tardy and would only make known
the gaseous condition of certain points that become, under
the natural conditions in mines, more or less isolated from
the points of greatest danger at the working face. To be
of practical value a determination of gas must be made
promptly and at the point of danger. The pipes leading
to the several working places as proposed for the working
out of this system were to be J inch in diameter, and the
claim that these would serve in a measure to drain the
gas from the workings was of course absurd. A small
pump was to be employed at the surface to draw the gas
from the mine. The attempt to enforce the adoption of
this system in the gaseous mines of Pennsylvania by
legislative enactment was frustrated, largely through the
efforts of Mr. Rufus J. Foster, mining engineer and editor
of The Colliery Engineer, now Mines and Minerals, and
serves as an illustration of one of the numerous dangers
to which mining operations are constantly exposed from
unwise legislation.

202. The Shaw Gas Machine. — This machine depends
on the principle explained in Art. 88 with respect to the
explosive limits of pure methane. The explosive limits
of all inflammable gases are fixed, but this condition de-
pends on the purity, and the density of the gas as influ-
enced by pressure and temperature. The theoretical con-
sideration of the principle involved in this machine would
contemplate some points of which the machine takes no
cognizance. For example, when calculating the per-
centage of any feeder gas that will render mine air explo-

THE SHAW GAS MACHINE 317

sive, there are two points at least that seriously embarrass
such a theoretical calculation, but which do not interfere
with the practical results obtained with the machine.
Thus, the feeder gas is a mixture of different gases and
its composition in most cases is unknown, while the
mine air itself is contaminated with other gases, besides
having lost some of its oxygen. A little reflection on the
method in which the explosiveness of the mine air is de-
termined in the use of the machine will make it clear
that the question here is what proportion of the feeder gas
added to the mine air with all its impurities will bring
the mixture to the explosive point. This determination
is not worked out, therefore, as a theoretical question^
and the percentage obtained in any given case is not
the percentage of pure gas mixed with pure air that is ex-
plosive, or even the percentage of feeder gas in pure air, but
merely the percentage of feeder gas that will render the
mine air explosive, contaminated as it is with other com-
bustible gases, including fine dust in suspension and ex-
tinctive gases, and depleted in oxygen.

As shown in Fig. 59, the machine consists of two cylin-
ders, A and B, having air-tight pistons attached to and
operated by the strong lever arm G, which in turn is oper-
ated by the connecting rod V and an eccentric driven by
the gears P and the crank N. The large air cylinder A
is fixed, while the small gas cylinder B is made to slide
along the graduated scale S. The graduations on the
lower scale S correspond to those on the beam G, and
both express in percentage the volume ratio of the two
cylinders (piston displacement) for any position of the
cylinder B. This cylinder is set by a small index mark
on its side and clamped by the arm seen extending below
the scale under the cylinder; the crosshead to which the

318

MINE GASES AND EXPLOSIONS

pistoQ rod H is attached is set to the corresponding gradu-
ation on the beam and fastened by the set screw C. The
construction of the machine is such that gas may be
mixed with air in any required proportion^ and the per-
centage of gas in the mixture will be determined by the
graduations to .1 per cent. By turning the crank N the
pistons in both the air and gas cylinders are moved up
and down together. Each cylinder is connected below

Fig. 59.— The Shaw Gas Machine

by means of the rubber tube M and a pipe underneath
the frame, to the distribution box L, which consists of
two closely fitting disks, the lower one being fixed while
the upper one is rotated to and fro by the rod W driven
by the gear wheel P. Such is the arrangement of the
valve ducts within the box L that at each stroke of the
beam and pistons air and gas from a main or other sup-
ply are drawn into their respective cylinders, from which
they are forced back through the distribution valve L
and thence into the mixer K, whence they flow into tha

THE SHAW GAS MACHINE 319

combustion chamber Z. This is a brass tube about
12 inches long and 1.5 inches in diameter, closed at one
end and provided at the other with a movable piston
so' placed as to be driven forcibly against the gong J
whenever an explosion occurs within the cylinder Z.
In the operation of the machine the mixture of air and
gas flowing from the mixer K fills the combustion tube Z
and issues from the small orifice seen on the side about
the center of the tube, this orifice being immediately
above a gas jet that is burning and by which the mixture
is ignited if it is inflammable. If the mixture is explo-
sive its ignition at the orifice will cause the explosion,
of the contents of the tube, which will be accompanied
with the ringing of the gong as explained.

The method of determining the percentage of gas in a
mixture of that gas and air is briefly as follows :

It must first be determined by trial what is the least
proportion of the gas that will form an explosive mixture
with pure air. To do this the tube shown on the right of
the distribution box L is left open so that pure air will be
drawn into the cylinder A when the pump is operated;
the cylinder B is always connected through the box L to
the gas main or other supply and therefore pumps gas.
By a few trials the position of the cyhnder B is soon found
where the mixture in the combustion tube Z is feebly ex-
plosive. The readings of the graduated arm and scale,
which must correspond, will show the percentage of gas in
the mixture and make known the higher explosive limit of
the gas (Table 12). This operation is called standardizing
the gas.

Having found the percentage of this gas required to
cause explosion, it is now possible to determine the per-
centage of the same gas in any mixture of the gas with air

320 MINE GASES AND EXPLOSIONS

not exceeding the higher explosive limit of the gas. To
do this the air to be tested is drawn into the air cyUnder A
through the tube shown on the right of the box L by con-
necting this tube with the bag containing the air or other
source of supply. Instead of pure air cylinder A may
now be pumping a small percentage of gas, which with
the gas being pumped by cylinder B would cause a violent
explosion in the combustion tube Z. To avoid such an
explosion it is well to set the cylinder B back a little, and
by trial the point is soon found where the mixture is feebly
explosive as before. The amount the gas cylinder B has
been moved back evidently shows the percentage of gas
contained in the air tested. It is claimed that the gradua-
tions of the beam and scale have been made to read per-
centages, but it is evident that when the scale expresses
correctly the percentage composition of the contents of
the two cylinders it cannot at the same time express
correctly the percentage of the gas contained in the air
in the large cylinder alone. When the percentage marking
the explosive limit is low, however, the results obtained are
correct for all practical purposes in mine work. For exam-
ple, suppose it is found on trial that a certain feeder gas in
a mine begins to explode feebly when mixed with pure air
in the proportion of 8 per cent, of gas and 92 per cent, of
air. A mixtm-e of this gas and air contained in a bag
when tested required the gas cylinder to be set back to
6 per cent, to obtain a feeble explosion, thus showing
8 — 6 =2 per cent, of gas in the air tested. This is actually
2 per cent, of the mixture after the 6 per cent, of gas had
been added, making 2 volumes of gas in the 94 volumes of
test air, or -^x 100 =2.13 per cent, nearly.

203. Use of the Shaw Gas Machine. — ^A difficulty would
^rise in the use of this machine if the air tested contained

THE SHAW GAS MACHINE 321

a greater percentage of gas than that marking the higher
explosive limit. In this case, if the mixture is within the
explosive range of the gas, a very violent explosion may
be obtained or the explosion may be quite feeble, accord-
ing to the near approach to the maximum explosive point
or one of the explosive Umits (Art. 88). The results ob-
tained in such a case are at times very confusing, because
if the mixture exploded in the combustion tube is between
the lower explosive limit and the maximum explosive
point, setting the gas cylinder back may increase the force
of the explosion and setting the cylinder forward so as
to increase the proportion of gas may actually cause the
explosion to cease. The writer has had this occur a
number of times when engaged in calibrating the sight
indicator. There are different ways of determining the
percentage of gas in such mixtures by changing the con-
nections. Thus, working from the higher explosive limit
of the gas as a standard: (1) Cylinder A drawing test air
and cylinder B drawing gas, it is possible to determine any
percentage of gas from zero to the higher explosive limit
by moving the gas cylinder to any position between stand-
ard and zero. (2) Cylinder A drawing test air and cylinder
B drawing pure air, it is possible to determine percentages
of gas above the higher explosive limit by moving the gas
cylinder forward to any position whatever on the scale.
In this case, however, the percentages are not read from
the scale, but must be calculated; this, indeed, is true
also in case (1), but the error there in taking the scale
readings as percentages is sHght. (3) Cylinder A drawing
pure air and cylinder B drawing test air, it is possible to
determine high percentages of gas only, since in this
arrangement the only gas pumped is but a fraction of the
flow from the small cylinder and it is only when the per-

322 MINE GASES AND EXPLOSIONS

centage is high that this can reach explosive proportions
in the combustion tube of the machine.

Letting J=the required percentage, >S=the higher ex-
plosive limit found in standardizing the gas, and R = th.e
reading of the scale, the following formulas represent
respectively the three arrangements described above:

im^y^''^

1- ^= T7^?7-P 100; (31)

(m)i^^>

2. ^-^j?;?rrp)ioo; ...... (32)

3. ^^=§100 (33)

It is apparent in the first case, formula 31, that R cannot
exceed S in value, and when R=S the percentage of gas
is zero. In the third case, formula 33, R cannot be less
than S in value, and when R=S the percentage is 100.
Again, in the second case, formula 32, giving R its great-
est possible value, R=25 (see scale. Fig. 59), J=iS, which
shows the highest percentage of gas that can be deter-
mined by this arrangement. In like manner the least pos-
sible percentage of gas that can be determined in the
third case is found by making R = 25 when J=4S. Com-
paring these two last cases it is apparent there is quite a
gap between %S and 4:S that cannot be determined by any
of these methods.

It is possible, though not as convenient, owing to the
gas being sharper and the explosions more violent, to
work from the lower explosive hmit of the gas, standard-
izing by this hmit instead of the higher hmit as previously
described. The same formulas will apply in the same man-
ner as described above; but it is apparent that the value

THE SHAW GAS MACHINE 323

of S being increased it is possible to cover some of the gap
not covered previously. Calling the standard correspond-
ing to the higher explosive limit Sh and that of the lower
limit Sz, the gap still remaining is from ^Si to 4uSh. It is
not possible to determine percentages directly in this
gap with the machine graduated only to 25 per cent.,
the relative volumes of the two cylinders remaining un-
changed; the volume ratio of these cyhnders is now 3:1 =
air: gas. It is possible, however, to make such determina-
tions indirectly; that is to say, by reducing or increasing
the percentage of gas in the air to be tested, preferably
the former. For example, suppose the air to be tested
actually contains 25 per cent, of gas (methane). The
values of the higher and lower explosive Hmits of methane
(Table 12) are respectively Sh =7.14 per cent, and Si = 16.67
per cent.; hence ^Si=2^,22 per cent, and 4/5/^=28.56 per
cent., so that this mixture will not give results in any
of the arrangements explained, whether standardized
by the higher or the lower explosive limit. But, con-
necting the bag containing the air to be tested with the
small gas cylinder, and setting this cylinder out to the
end of the scale (25 per cent.) and operating the pump,
a new mixture will be pumped containing 25 per cent, of
the test air. In other words, the percentage of gis con-
tained in this new mixture will be exactly one-fourth of
the percentage in the original test air. This new mix-
ture containing then 6.25 per cent, of gas can be caught
in a bag attached at the mixer K, and can then be easily
tested by the first method described, and the resulting
percentage multiplied by 4 will give the true percentage
of gas in the air.

The Shaw gas machine is a valuable machine, but is
not adapted to underground work under any possible con-

324

MINE GASES AND EXPLOSIONS

ditions because it is not portable, and by the time air
is bagged and taken to the surface and the percentage
of gas it contains determined, the condition in the mine
may have wholly changed, becoming more dangerous or
less so. Moreover, the air taken in the bags represents
only a local condition, and does not therefore possess the
general value that it should to assist the practical operation
of the mine. Any determination of the percentage of gas
in the air of mine workings must be made promptly at
the point of suspected danger, in order that immediate
remedial measures may be at once adopted.

204. The Beard-Mackie Sight Indicator. — This device is
the joint invention of the author and Mr. Matthew D.
Mackie, an experienced fire boss of the Marvine Colliery,
Scranton, Pa. It was first introduced in mines in March,
1903. Fig. 60 shows the indicator detached from the
lamp. It consists of "A fi-^haped support made of No. 14
brass wire and riveted to a brass
disk, which forms its base and fits over
the wick tube of the lamp. The in-
dicator is thus held firmly in position
in the lamp by the same nipple that
secures the burner. As shown in Fig.
60, supported on this frame are seven
platinum cross wires — a straight stand-
ard wire at the bottom, and above
this six percentage wires each having
a small loop or circle in the middle.
The loops enable the incandescent wires
to be more readily and quickly dis-
cerned within the gauze of the lamp.
The lower standard wire is for the
purpose of gauging the height of the lamp flame in

n .

. 0 .

0 ,

. o .

n .

. o ,

Standard

Wire

».-

354

25{

Fig. 60.— The Beard-
Mackie Sight Indi-
cator Detached
from Lamp

THE BEARD-MACKtE SIGHT INDICATOR 325

pure air. The presence of gas is then made known by the
incandescence of the successive percentage wires, the per-
centage of gas being indicated at once by the number of
wires aglow. The successive percentage wires indicate
respectively 0.5, 1, 1.5, 2, 2.5, and 3 per cent, of gas in
the air. ...

205. Principle of the Sight Indicator. — "The device de-
pends upon the well-known property of platinum of in-
ducing the union of oxygen and other gases in contact
with its surface, which property is possessed by the com-
pact metal to a less degree than spongy platinum only in
proportion as its surface is less than the surface of the
latter. The stimulation of the chemical activity at the
surface of the metal when gas is present is sufficient to
maintain a red heat in a platinum foil. This is shown by
heating the foil to redness in a gas flame and then shutting
off the gas suddenly and at once turning it on again. While
the heat developed in this case is not sufficient to cause
the gas to ignite, it maintains a red glow in the platinum,
which only ceases when the gas is shut off. The degree of
heating is determined by the ratio of the surface to the
volume of the metal, which -in the case of spongy platinum
is sufficient to cause the ignition of the gas and which in
the fine wires of the indicator causes a white heat that
enables the lamp to hold its flame, relighting the lamp after
extinction in ' sharp ' gas. This feature, which is of great
advantage in the work of testing for gas in the mine, has
been often proved both in the mine and in the laboratory
when the lamp has been introduced into an atmosphere of
gas that was extinctive owing to the excess of gas. All
flame would then die out within the lamp, the wires alone
remaining incandescent and relighting the gas when the
lamp is slowly withdrawn, the gas in turn relighting the

326

MINE GASES AND EXPLOSIONS

lamp. It is noteworthy that the platinum wires incan-
desce at a considerable height above the tip of the flame,
owing to the peculiar property of the platinum that stimu-
lates the combustion of the gas in contact with its surface
"The underlying principle of this device is practically the
same as that involved in the Liveing indicator, . . . but
in the Liveing indicator the original source of heat is an
electric current made to pass through the platinum wire,
while in the present device the heat is derived originally
from the flame of the safety lamp in which the indicator
is placed. . . .

206. Experiments Previous to Calibration. — "In the cali-
bration of the indicator an unbonneted Bslyj lamp (Fig.
61) burning pure sperm oil was used.
The lamp was hung in a small wooden
box 10 in. by 10 in. by 16 in., shown
in Fig. 62. This box was connected
below and above with a 10-inch pipe
that formed a stack for the escape of
the gas. The box was provided with a
glass door at the front, through which
the behavior of the lamps could be dis-
tinctly observed ; the pipe was open at
the bottom and top to permit the free
upward passage of the air and gas.
City gas was used, and this was intro-
duced into the lower end of the stack
by the rubber tube leading from a gas
jet above. A damper in the pipe just
above the box allowed the operator
to accumulate the gas so as to obtain
any desired gaseous condition of the air passing through
the box in a constant stream; and it was also possible to

Fig. 61.— The Eeard-
Mackie Sight Indi-
cator in Davy Lamp

THE BEARD-MACKtE SIGHT INDICATOR

327

maintain this constant condition of the passing current
for any length of time, so as to enable a test to be made
with the Shaw gas machine located at one side of the box.
A rubber tube connected this machine with a short brass
pipe inserted in the back of the box and extending to its
center, terminating at a point
close to the gauze where the feed
air entered the lamp. By this
means it was possible to obtain
an accurate test of the air that
was feeding the lamp, at any de-
sired moment.

"Before placing an indicator in
the lamp, experiments were made
to ascertain, the relation between
the heights of the flame cap and
the percentages of gas causing the
same, for the purpose of confirm-
ing the law formulated by Mr.
William Galloway, which says
that the height of the cap varies
with the cube of the percentage
of gas present in the air. The
height (h) in inches for the per-
centage (J) was thus found to be
expressed by the formulas

Unbonneted Davy (sperm oil), J='VsQh (Beard);
Bonneted Davy (sperm oil), J =^m (Galloway).

207. Calibration of the Sight Indicator. — "Having made
these preliminary tests, an indicator frame, with cross
wires of platinum arranged upon it at uniform distances
apart, was placed in the lamp, and careful observations

/ V^

Fig. 62.— Test Chamber Used
in Calibrating the Beard-
Mackie Sight Indicator

(34)
(35)

328 MINE GASES AND EXPLOSIONS

made to ascertain the relation of the height of incandes-
cence of these wires to the percentage of gas in the air
passing upwards through the box. By this means the
heights of the several percentage wires were determined.
These observations and experiments, repeated many times
and in different ways, revealed the discouraging fact that
it was seemingly impracticable to attempt to insert a
0.5-per cent, wire, because its position was too close to
the standard wire used to gauge the flame. So close would
this first percentage wire be to the standard wire that it
required considerable care to set the flame so that it would
incandesce the latter without causing both to glow. This
difficulty, however, was successfully overcome later by
using a slightly heavier iron wire in place of the platinum
standard wire. This iron wire had the effect of kilhng the
heat in the immediate tip of the flame, with the result
that each of the three lowest percentage wires had to be
raised. The lowest of these, or the 0.5-per cent, wire,
was raised the most; that next above a less amount; and
the upper one of the three the least of all. The three
upper percentage wires were not disturbed in their posi-
tion by the introduction of the iron wire for a standard
wire. The idea of thus killing the heat in the extreme
tip of the flame was suggested by the principle of Sir Hum-
phrey Davy's wire gauze.

"The iron standard wire, however, proved a source of
annoyance in the use of the indicator in strong gas. It
would burn out in a short time, and required to be replaced
by another wire. Further experiment showed that copper
wire could not be used, probably owing to its high con-
ductivity; aluminum, likewise, has a comparatively high
conducting power, and, in addition, it would not stand the
heat of the flame. Finally, the use of a platinum wire of

ADVANTAGES OF THE SIGHT INDICATOR 329

a somewhat lower gauge was found to meet every require-
ment, and this was adopted.

208. Advantages of the Sight Indicator. — '^The advan-
tage of the sight indicator over the usual method of testing
for gas may be briefly stated as follows : With the normal
working flame of a Davy or Clanny lamp burning ordi-
nary sperm or lard oil, it makes plainly visible within the
lamp the slightest change in the gaseous condition of the
mine air, and indicates with great • accuracy the exact
percentage of gas present, in amounts varying from 0.5
to 3 per cent. Beyond this quantity the percentage of gas
is estimated readily by the usual method of observing the
height of the flame cap, which is then clearly discernible.
No time is lost in drawing down the flame when making a
test, and the risk of losing the light is eliminated. The
indicator, operating continuously and automatically, re-
veals the presence of unsuspected gas where a test by the
usual method would be considered unnecessary; a possible
accident may be thereby averted. Aside from the actual
determination of the percentage of gas present in the air,
however, the chief advantage of such a device in a mine is
its power to show constantly any fluctuation in the per-
centage of gas.

"The test is quickly made, as the wires respond promptly
to the slightest change in the gaseous condition of the air.
A change caused by the accidental setting open of a door,
and the consequent derangement of the ventilating current,
or the Hberation of gas by a fall of roof in another portion
of the mine, or an increased outflow of gas from old work-
ings, caused by a sudden fall of the barometer, or even an
increased quantity of inflammable dust in the air, will at
once be shown by this silent monitor, as has been proved
in several instances in the mine. It is already reported

330 MINE GASES AND EXPLOSIONS

as having been the direct means of saving men's lives by
indicating an unsuspected increase of gas where it was not
thought necessary to stop to make a test. This will be
understood when it is remembered that the device gives
its indication with the normal working flame, the bright
incandescence of the wires being clearly seen, notwith-
standing the brightness of the lamp flame. This is a
great advantage over the flame-cap method, in which it
is necessary first to stop and lower the flame of the
lamp to a mere glimmer before making the test. In
doing this there is incurred not only the loss of time,
but the risk of ' getting in the dark,' which every miner
rightly dreads.

"The appreciation of the value of this device for the
purpose named is shown by the fact that special lamps
have been designed for its use in England and also in
France, because the mining laws of these countries for-
bid the use of an unbonneted Davy lamp in a gaseous
mine, and it was thought best to design a special lamp in
each case. Fig. 61 shows the sight indicator in a Davy
lamp." *

Special forms of the Clanny and Marsaut lamps (Fig. 36),
having a 3.5-inch glass and admitting the air below the
flame, have recently been designed, which give good
results with the indicator. The special form of EngHsh
lamp of the Ashworth-Hepplewhite-Gray type, designed
for the indicator, is shown in Fig. 45.

* Transactions American Institute Mining Engineers, Vol. XXXVII.
pages 249-255.

THE FLAME TEST 331

THE FLAME TEST

209. The effect of gas in the atmosphere surrounding
and supporting a flame, to alter both its shape and size,
has been observed from the earhest times in connec-
tion with testing for gas in mine workings. Before the
invention of the safety lamp or the use of the steel mill,
when the naked candle flame was the only practicable
source of light, the intrepid miner shading his eyes from
its glare would cautiously raise this flame toward the roof,
watching furtively as he did so for any increase in its
height, or for the first appearance of the faint blue cap
that indicated the presence of inflammable gas. It was
then as now the flame test, though appHed under conditions
far more dangerous.

210. The Visible Effect of Gas on Flame. — The effect of
extinctive gas on flame has been explained in Arts. 116
and 182; and at this time there will be treated only the
visible effect of inflximmable gas on flame enveloped in its
atmosphere, as forming the basis of the flame test. When a
flame is burning in an atmosphere containing a small pro-
portion of inflammable gas, the amount being insufficient
to permit of its separate inflammation, the gas in the air
in immediate contact with the flame will be consumed,
its combustion adding to the volume of the flame with
which it is then identified and of which it forms a part.
The combustion of this gas in contact with the surface of a
lamp flame produces a thin envelope of pale-blue flame,
which is naturally only visible above the tip of the lamp
flame where a non-luminous flame cap is formed. The
height of this flame cap has been found to vary with the
proportion of gas present and its degree of inflammability
as well as the inflammability of the illuminant producing

332 MINE GASES AND EXPLOSIONS

the original flame. Besides the appearance of the flame
cap caused by the gas present in the surrounding air, the
height and to a less degree the volume of the original
flame is increased as a result of the same causes as men-
tioned above. For any given percentage of gas both the
height of the flame and that of the cap vary with the
illuminant, being greater for the more volatile oils and for
gas-fed flames than for the ordinary burning oils.

As a general proposition anything that affects the com-
bustion on which the cap depends affects to a greater or
less degree the height of the cap. The condition within
the lamp is a most important factor in this respect. Those
lamps like the unbonneted Davy that afford to the largest
extent a free circulation of air give the highest flame caps
for the same percentage of a gas and the same illumi-
nant. Where the circulation in the lamp is restricted by a
bonnet, the height of the flame cap for like conditions
is reduced. It is owing to this fact that many good
working lamps do not make good testing lamps.

211. Relation of Height of Flame Cap to Percentage of
Gas. — From what has been described above, it is clear
that the height of flame cap due to any given percentage
of gas is greatly modified by the form of the lamp and the
kind of illuminant used. In the same lamp, however,
burning the same illuminating oil there is a practically
fixed relation between the height of flame cap and the
percentage of gas present in the air at the time of making
the test. This relation is more exact the greater the
freedom of circulation in the lamp; a restricted circulation
interferes with the development of this law in proportion
as it affects the gaseous condition of the atmosphere within
the lamp. A bonneted lamp, with a direct circulation on
the Eloin principle, will conform closer to the law than an

THE FLAME TEST 333

unbormeted Clanny lamp with opposing air-currents.
The unbonneted Davy lamp with a 4J- or 5-inch gauze
below the smoke gauze or cap, has a free circulation and
gives better results in testing for gas than most other
lamps, because the condition in the lamp very closely
represents the condition of the outside air. A well-designed
Eloin lamp also represents practically the same condi-
tion within the lamp as exists in the outer air.

As explained in Art. 206, Mr. William Galloway, by a
number of experiments discovered the law that the height
of the flame cap varies as the cube of the percentage of gas
present in the air, for the same conditions. Mr. Galloway
found, using a bonneted Davy lamp, the height of the
flame cap in inches was practically yV of the cube of the
percentage of gas present and producing the cap. The
writer found in a long series of experiments that in an
unbonneted Davy burning a good quality of sperm oil
the height of the flame cap was practically ie of the
cube of the percentage of gas present; these laws are
expressed in formulas 34 and 35. The experiments of the
writer were performed in the box arranged as shown in
Fig. 62, which afforded exceptionally favorable conditions
for obtaining an exact measurement of the gaseous con-
dition of the atmosphere producing any given height of
flame cap. To determine the height of flame cap corre-
sponding to any given percentage of gas, formulas 34 and
35 may be written

Unbonneted Davy, sperm oil (Beard) ^ =o^- (36)

Bonneted Davy, colza oil (Galloway) h^-=7:. (37)

The height of the cap depends to a certain extent also
on the height of the original flame. The above formulas

334 MINE OASES AND EXPLOSIONS

are based on data derived from the smallest possible flame,
which is practically J inch in height. Prof. Clowes has
drawn attention to what he calls the maximum height of
cap for any given percentage of gas, which he states may
be obtained by drawing down the wick till the cap attains
its greatest height. Such a standardizing of the flame
in making a test in the mine can hardly be considered as
practicable, owing to the risk incurred of losing the flame.
For all practical purposes this is an unnecessary refinement
in making a test in the mine. As explained (Art. 102),
gas has a tendency to stratify and move in veins, which
frequently cause some considerable variation in the results
of tests that should seemingly agree. Occasionally it will
happen that a lamp will fill with flame, as it has in the
writer's experience, which as quickly passes away, so that
there is only a trace of gas remaining, and this without
moving the lamp. There is always an increasing per-
centage of gas shown on the lamp as it is approached closer
to the source of the feeder.

It is owing to these conditions in the mine that a
fire boss using the ordinary flame test and the common
Davy lamp wifl frequently report ''no gas," when in
reality there is a large quantity of gas being given off,
which only requires some sUght derangement of the venti-
lating current to produce a dangerous atmosphere. With
the large volumes of air now being circulated in mines it
is more necessary than ever before that the lamp of the
fire boss should detect the smallest possible percentages
of gas, and indicate by some simple ready means of measure-
ment the exact percentage of gas present in the air, so as
to eliminate once for all the irresponsible custom now in
use of guessing the height of the cap, and the inability of
the observer to see the smaller caps.

HEIGHTS OF FLAME CAPS

335

212. Flame Caps of Different Illuminants in Different
Lamps. — In general it may be said the common burning
oils are better adapted to detect the larger percentages of
gas, say from 2.5 to 6 per cent., while the lighter mineral
oils, alcohol and hydrogen gas, are of use in detecting the
lower percentages, from 0.25 to 3 per cent. The form of
lamp used also modifies the height of the cap for any given
percentage of gas. The following table is of interest in
comparing the heights of flame caps produced by different
illuminants in different lamps. It will be observed benzo-
line burned in the Ashworth-Hepplewhite-Gray lamp pre-
sents the widest range of any of the other illuminants, but
is not as sensitive in the detection of a slight gaseous
change, because the difference in the heights of cap pro-
duced by such a change is small.

Table 25

HEIGHTS OF FLAME CAPS FOR DIFFERENT ILLUMINANTS AND
LAMPS— REDUCED FLAME

Lamp

Percentages of Gas

Ilium inant

.25

.oa

1.0

1.5

2.0

2.5

3.0

4.0

5.0

6.0

Heights of Flame Caps (Inches^

Sperm or
lard oil

Davy \
(unb't'd) /
Davy 1
(bon t'd) /

.22

.43

.75

1.75

3.50

Colza 1

.22

.38

.88

1.80

3.20

Colza

A-H-G

.20

.30

.50

1.20

2.70

Benzoline

Ashworth

.20

.30

.40

.50

.60

.70

.80

1.00

1.20

1.40

Naphtha f
(benzine) \

Wolf

.35

.40

.52

.72

1.16

2.76

Alcohol

Ashworth

1.10

1.90

3.00

Alcohol

Pieler

1.20

2.00

3.00

4.00

5.00

Hydrogen 1

Clowes- \
A-H-G /

.90

1.10

1.20

1.40

1.75

2.30

336 MINE GASES AND EXPLOSIONS

For the purposes of testing, the hydrogen flame possesses
the advantage that it is not as easily extinguished by the
presence of carbon dioxide and other extinctive gases.
On the other hand, alcohol and the light mineral oils are
very susceptible to the action of these gases, which is one
of the chief objections to their use for the work of testing.
There is some difference in the observed heights of the
flame caps as recorded by different authorities, owing
chiefly to the use of different lamps, different grades of
illuminants, and possibly also a difference in the quality
of gas tested, but the differences are not important. What
is required in the practical work of testing for gas in the
mine is a thorough acquaintance with the lamp and oil
used, in respect to the behavior of the flame and the
heights of the several caps as indicating the percentages
of gas present. Of more importance still is the ability
to rightly interpret these caps or percentages as indicat-
ing the degree of danger in the mine air with respect to
gas and dust, remembering that percentage is only another
name for condition in the mine. It matters little whether
such percentage conforms absolutely to that given for the
same height of cap in a test of the gas in the laboratory.
In the practical work of testing in the mine the measured
height of flame cap is a valuable index of the explosive
condition of the mine air, and percentage is merely a con-
venient name describing such conditions in a manner that
will show their relative danger. It is therefore essential
that some accurate means be employed for measuring
the exact heights of the caps formed, or otherwise accu-
rately gauging the gaseous condition of the air.

213. Measurement of Flame Caps in Testing Lamps. —
For the purpose of accurately measuring the heights
of the hydrogen flame used for testing for gas in the

MEASUREMENT OF FLAME CAPS

337

Clowes hydrogen lamp (Art. 173), Prof. Clowes em-
ployed a ladder scale, which is shown attached to the
lamp vessel in Fig. 43. This scale is shown more in de-

Top Qf burner

Fig. 63. — Section of Oil Vessel of Clowes Hydrogen Lamp, showing
Attached Scale for Measurement of Flame Caps

tail in Fig. 63, together with a scale of inches at the right
to show the actual heights of the several flame tips. As
shown, the original height of the flame is .4 inch above the
top of the burner, from which point all measurements are

338 MINE GASES AND EXPLOSIONS

made. The flame is adjusted in air free from gas, so that
its tip just reaches the top of the first cross-bar. The
cross-bars above this are arranged at such heights as to
indicate 0.5, 1, 2, and 3 per cent, of gas respectively, each
of these bars, however, being set exactly .2 inch below
the tip of the corresponding flame, so that the bar will
readily appear as a black line across the flame near its tip.
Thus the height of the flame tip for 3 per cent, of gas is
2.5 inches, while the top of the corresponding cross-bar
is 2.3 inches; this difference is readily gauged by the eye.
When more than 3 per cent, of gas is present, the deter-
mination is made with the oil flame as follows: the wick
being first raised and lighted, the supply of hydrogen
is then turned off and the wick is drawn down, so that
the oil flame would only be .1 inch high in air free from
gas. The heights of cap corresponding to different per-
centages of gas are then as follows: 4 per cent., 0.6 inch;
5 per cent., 1.3 inches; 6 per cent., 2.8 inches; these
heights of cap for the given percentages being obtained
in the Ash worth type of the Clowes lamp. There will
be some slight difference in the heights of cap for the same,
percentage of gas when drawing the air from above the
lamp having the lower inlet openings in the tubes closed,
because of the retardation of the circulation in the lamp.

In the Pieler lamp (Fig. 39) and the Chesneau lamp
(Fig. 40) scales for the estimation of the cap are arranged
on the outside of the lamp. The platinum-wire scale of
the Beard-Mac kie lamps (Art. 174), arranged within the
lamp, acts on a different principle from a simple measuring
scale. The cross wires here glow at heights somewhat
above the tip of the flame (Art. 205). This scale is used
with the normal working flame, which is not reduced
when testing with the indicator.

TESTING FOB GAS

339

214. Care of Lamp. — ^Every fire boss, fireman, or mine
examiner should take the entire care of his own lamp,
which must be thoroughly cleaned after each shift. Par-
ticular care must be taken to brush out the gauzes; these
should be removed from the lamp for "the purpose. Two
kinds of brushes are in common use: the bristle brush
shown at (a) (Fig. 64) and the metallic brush shown at
(&). At (c) is shown the common straight gauze of the
Davy lamp, and at (d) the conical gauze mostly used in

(a) Cb) (c) (cO (e)

Fig. 64. — Lamp Brushes, Gauzes, and Glass

Marsaut and Mueseler types. Each of these gauzes is
provided with a gauze cap or smoke gauze, as it is some-
times called. It is important to remove this cap and
brush out the soot and dust that collects there, but care
is required in doing this not to injure the mesh of the
gauze. The indent or crease shown in the cap of the
gauze at (d) is to prevent the cap from being pushed too
far down on the main gauze. The glass (e) should be
cleaned and rubbed dry. The wick should be carefully
trimmed, a new wick being put in the lamp at least once

S40 MINE GASES AND EXPOSIONS

a week and oftener if the oil shows a tendency to thicken
and gum or make the wick greasy. Short wicks often
renewed are better than long wicks, and give a better light.
The lamps should be filled, not too full, with a good quality
of sperm or lard oil, to which the fire boss has added half
its volume of coal oil, or kerosene having a flashing point
not lower than 80° F.

215. Examining a Mine for Gas. — ^When examining a
mine or any portion of it for gas, the work should begin at
the intake end and proceed v/ith the air. Care is needed
to avoid the possibility of walking into a body of fire-
damp. This will sometimes happen when a fire boss
enters a room or chamber where the circulation is slack.
The gas may be working out from the room in a thin
layer along the roof, and the quick passing of a person
under this may disturb the gas and cause it to descend
behind him as he goes towards the face of the room un-
conscious of his danger. On suddenly becoming aware of
the presence of the gas and turning to retreat he finds to
his dismay the whole place filled with gas. He is fortunate
if he can escape from the disturbed atmosphere of the
room by a nearby cross-cut into another chamber as yet
undisturbed, and through which he may perchance reach
the purer air of the entry. For lack of sufficient caution
and in haste to complete his morning round many an un-
wary fireman has been thus suddenly entrapped in a
body of gas from which retreat is uncertain and dan-
gerous.

The approach to a known body of gas should always
be made on the intake side to avoid being enveloped in the
tail of gas before reaching the seat of the trouble, and to
have a clear retreat open should it be necessary to with-
draw quickly. The examination of a mine before the men

TESTING FOR GAS 341

are allowed to enter for work should be thoroughly exe-
cuted. The person or persons making this examination
should be conscientious in the performance of the work,
and no place shoukl be assumed to be free from gas except
for a good and valid reason that would justly warrant
such a conclusion. The fire boss is responsible for many
lives and only such men as are fully trustworthy should
be chosen for the work.

216. Making a Test for Gas with a Davy Lamp. — Every
test should be made with caution, even where gas is not
suspected. There are two methods of making the com-
mon flame test with the Davy lamp: one by observing
the cap formed by the gas when the flame is drawn down
to a mere glimmer, and the other by observing the in-
crease in the height of the normal working flame due to
the presence of gas. The cap test or the test by the
reduced flame is by far the one most commonly used and
the most reliable. Both methods, however, are crude ap-
proximations, permitting of much guesswork on the part
of the examiner, often making him the autocrat of the
situation, and loading him with responsibilities he is,
or should be, unwilling to assume.

When about to make a test with the reduced flame, the
lamp having been prepared in the manner described
(Art. 214), the flame is first drawn down with the pricker
to a glimmer varying from | to I inch in height, accord-
ing to the individual preference of the examiner. The lamp
is then raised cautiously in an upright position towards
the roof. Fig. 65 well illustrates the characteristic pose
when examining a gas pocket in the roof. It is readily
understood that nothing less than a 1-inch or a 1.5-inch
cap would be detected in this position of the lamp. When
examining for a thin layer of gas at the roof, in a chamber

342 MIAE GASES AND EXPLOSIONS

or heading, it is necessary to disturb the gas slightly with
the cap or a movement of the hand, or, as is often done, by
blowing against the roof. Then, holding the lamp upright
in one hand and screening the main body of the flame with

Fig. 65. — Making a Test for Gas

the other, it is possible to detect a cap somewhat less than
J inch in height, indicating 2.5 per cent, of gas (Table 25).
The practice of turning the lamp on its side and drawing
or waving it along the roof is a dangerous one and ought
to be wholly discontinued. The lamp should always be

COMPARING METHODS OF TESTING 343

held upright when making a test. When making a test
in an air-current it is necessary to shield the flame from
the direct force of the wind; this is best accompUshed by
turning the back to the wind and holding the lamp in
front of the person in a protected position. The procedure
is the same when testing with the normal flame, but in
this case the height of the flame is observed instead of the
cap and the percentage is determined and reported accord-
ing to the experience of the observer.

217. Comparative Merits of the Flame Test and the
Sight Indicator. — In the use of the sight indicator it be-
comes unnecessary to make an actual test for gas, since
the indicator reveals constantly the gaseous condition of
the mine air. This is done with the normal working flame,
thus avoiding the risk of losing the light, which must
always be incurred when it is necessary to make a test
with a reduced flame. The indicator often reveals a
change in the gaseous condition of the air too small to be
detected on the flame of the lamp by the unaided eye,
but which is important because it betrays the actual con-
dition of the mine in this respect. The existence of an
accumulation of gas is indicated at a distance from the
place where it is found and danger is often thus avoided.

It has been so long the custom to test for gas in the
mine in a crude way that many still hold to the beUef that
there is no danger from this source as long as the propor-
tion of gas is not sufficient to produce a ''cap," which
means, in ordinary mining practice, anything under 3 per
cent., because the average miner does not call anything
less than this "gas." The report of the early-morning
examination made when the mine was idle and the air
passing through the workings clear and free from dust
reads "no gas"; and two hours later an explosion \vTecks

344 MINE GASES AND EXPLOSIOXS

the mine. Such was the sad tale of the terrible exploaion
in the Klondike workings of the Rolling Mill Mine, at
Johnstown, Pa., on the morning of July 10, 1902, when
112 souls were ushered into eternity, in a mine that had
just been examined by authorized and competent fire
bosses who had reported "no gas." It requires no argu-
ment to prove that such a system of testing is wrong.
The experiments of Galloway have proved that air con-
taining but .892 per cent, of marsh gas is explosive
(Art. 115), while the still more important experiments of
Hall proved quite conclusively that some dusts, under
certain conditions, are of themselves explosive and that
the ignition of such dust may be caused by a flame of suf-
ficient intensity in the entire absence of marsh gas or other
inflammable gases (Art. 131).

It is of the utmost importance to notice that an atmos-
phere that may seem to be perfectly safe when the mine
is examined in the early morning, may be changed into a
dangerous atmosphere when the mine is in operation.
This is particularly true in the working of a soft, inflam-
mable coal, but it is likewise true, though to a less degree,
in an anthracite mine. The writer has observed a differ-
ence of J per cent, between the reading of the sight indi-
cator at the roof of a chamber and one taken at the same
time and place near the floor in a cloud of anthracite dust
caused by the loading of a car, the higher reading being
at the floor ; there was 2 per cent, of gas at the roof and
2.5 per cent, at the floor. In another instance the indi-
cator showed a gradual but slow increase of the general
gaseous condition of a certain section of a mine, from day
to day, and the fire boss laid this gradual and steady
increase to the effect of a coming squeeze, which proved
to be only too true, it becoming necessary in a few days'

MEASURING QUANTITY OF GAS 345

time to draw the track from a portion of this section. In
another instance, by the timely warning of the indicator,
which showed an increase of 1 per cent, over the usual
reading in the air returning from a certain panel, three
men were stopped from running into a body of gas that
had accumulated between shifts by the accidental setting
open of a gate by men leaving the mine. The men had
open lights and would have been severely burned if not
killed but for the warning of the indicator.

There is a tendency among all miners more or less to
use too high a flame in a safety lamp. This is a bad
practice, because of the smoking and sooting of the gauzes.
The working flame of a saiety lamp should not exceed
from I to 1 inch, depending on the condition of the mine
air and the strength of the air-current. When the state
of the air approaches an explosive condition, or in a strong
current of air, the height of the flame should be reduced
accordingly. The use of a poor or inferior illuminating oil
gives rise to sooting, which impairs the efficiency of the
sight indicator and endangers the lamp by clogging the
gauze. With a good quality of sperm or lard oil in an
unbonneted Davy lamp, with a safe flame that will not
smoke the gauzes, there is no trouble from " sooting '^ in
the use of the sight indicator. But it is always true that
a good tool in the hands of a poor workman is capable
of no better results than a bad tool in the hands of a good
workman.

2i8. Measurement of Gas in Mines. — Strange as it may
seem, the common practice of reporting the quantity of
gas found in a chamber is even more crude than the method
of its detection. When gas is found at the face of a cham-
ber or heading, the quantity is estimated by the number
of inches down from the roof where the first appearance of

346

MINE GASES AND EXPLOSIONS

a cap was discovered; this quantity is reported as 6, 8,
or 12 inches of gas, as the case may be. Fig. 66 illus-
trates a possible condition at the working face of a room
where a considerable quantity of gas is issuing from the
coal. As the gas transpires from the face of the coal it
rises towards the roof, as indicated by the small arrows
and the dotted lines. The larger arrows close to the floor
represent the flow of fresh air toward the face, where it
rises and mixes with the gas. The circulation shown in the
figure is not rapid, the movement of the air and gas being
scarcely perceptible. It is evident that a test made for
gas imder these conditions would show almost any percent-
age of gas, according to the position of the lamp and the

Fig. 66. — Showing Condition with Respect to Gas at Face of a Chamber

delicacy of the test. The illustration shows a roof fall
between the timbers and a dangerous pocket of gas in the
cavity left in the roof. There would be a good oppor-
tunity for a hasty fire boss to lose his light here by incau-
tiously raising his lamp into this pocket. With some
lamps an explosion might be caused by the sharp gas
entering a lamp fifled with nearly pure air from the floor
of the chamber. This is more apt to occur with a closely

MEASURING QUANTITY OF GAS 347

bonneted lamp than with the unbonnetecl Davy, but the
latter must not be moved quickly when flaming, which
occurs in an atmosphere containing between 5 and 6 per
cent, of pure marsh gas.

When a current of air containing a certain per cent, of
gas is flowing in an airway, at a distance from the point
where the gas entered the current, the mixture of gas and
air is more uniform, and it is possible to estimate with
some degree of approximation the quantity of gas in the
current, or the quantity of gas given off in that section of
the mine each minute. But in a room or heading or any
other place in the mine where gas is being generated, as
illustrated in, Fig. 66, it is impracticable to attempt to
form any estimate of the quantity of gas being given off,
because the conditions are not uniform. In a general way
the report that a cap was obtained, say 6 inches from the
roof, at a distance of 10 feet from the face, or 20 feet from
the face, indicates roughly the condition of the room with
respect to gas. It shows whether the place is sufficiently
safe to enable men to work there, and suggests the precau-
tions it will be necessary to observe with respect to lights
at the face of the room.

The question is sometimes asked, In what percentage of
gas is it safe or possible for men to work? This question
cannot be answered in a way that would apply to all
mines, since the character of the gas, the degree of inflam-
mability of the coal, the intelligence and experience of the
men, the character of the ventilation, and many other
conditions would modify the answer to be given to such
a question in any particular case. Men should not be per-
mitted to work in any percentage of gas that approaches
a dangerous condition when it is practicable to reduce the
percentage of gas in the air. If this is impracticable, only

348 MINE GASES AND EXPLOSIONS

experienced men should be allowed to enter the place and
every precaution should then be taken to safeguard the
work. Men have mined coal in the dark because it was
very unsafe to approach a lamp to the face of the breast.
The work of mining under these conditions, however, is
very hazardous, as the slightest occurrence may result
fatally. It should be possible by some means to improve
the situation and render the work fairly safe. Ordinarily
the percentage of gas in the air coming from the face should
not exceed 2 per cent, for anthracite and 1 per cent, for
bituminous mines, but the particular character of the coal
or of the gas may alter this.

CARE OP MINERS' SAFETY LAMPS

219. All safety lamps used in a mine, except those of
the fire bosses (Art. 214) , should belong to the company
operating the mine. In this way the management will be
able to maintain proper supervision and control of the
lamps, which is of the utmost importance. It will also be
wholly at the option of the management what type or
types of lamps shall be used. By assuming the full charge
and responsibility of the safety lamps, the management
secures to itself the sole right to lock and imlock the lamps.

220. Requirements. — The proper care of a safety lamp
requires that it shall be thoroughly cleaned, filled, and
trimmed at the end of each shift. This work should be
done in a separate, properly equipped lamp house. Each
lamp should at least be carefully inspected by a competent
person before being given out for use in the mine. When-
ever practicable each lamp should be exposed to an atmos-
phere of firedamp in a test box or chamber, to ascertain
if the lamp is in perfect condition before it is taken into

THE LAMP HOUSE 349

the mine. Where a mine is particularly gaseous the test-
ing of lamps should be made imperative, also a careful
inspection. After the lamp is lighted it should be sub-
jected to the test box a sufficient length of time to prove
its security in gas (Art. 155).

As explained in Arts. 187 and 214, a good quality of
sperm or lard oil mixed at the mine with kerosene (coal
oil) having a flashing point not less than 80° F. should
be used in the proportion of two volumes of the former to
one volume of the latter. Short wicks (Arts. 189, 214) of
good quality should be used, and these should be often re-
newed to insure that the oil is fed properly to the flame.

The lamp should be examined to ascertain that it is
properly put together, and then locked by a duly authorized
person. Each lamp should bear a number corresponding
to the check number of the man who uses it, and when
returned to the lamp house a check bearing the same num-
ber is given to the man returning the lamp. As far as
practicable the same lamp should be given to the same
person from day to day.

221. The Lamp House. — ^There are several different ar-
rangements of lamp houses, that vary somewhat in detail,
but all possess certain features in common; namely, a
passageway for the men receiving or returning lamps, con-
venient lamp racks, a room for cleaning and filling the
lamps, furnished with proper benches or tables and the
necessary apparatus. In many lamp houses there is a
separate room for repairing broken or injured lamps.

The arrangement shown in Fig. 67 offers every facility
for receiving, inspecting, cleaning, filling, storing, lighting,
and delivering lamps. On coming out of the mine the
men pass into and through the passage a, leaving their
lamps at the windows marked o, and receiving in return a

350

MINE GASES AND EXPLOSIONS

brass or leather check bearing the same number as the
lamp returned. The lamps thus received are examined in
the room b, where they are unlocked and taken apart.
The gauzes of the lamps are thoroughly cleaned with a good
brush (Fig. 64), the glasses polished, and the oil and dirt
wiped from the lamp. In case the number of lamps in use

Fig. 67. — Showing Arrangement of Lamp House

is large, a special cleaning machine having rotating brushes
is often installed in this room. If lamps are found on
inspection to require repairs, they are held in this room
till this can be done, work benches for the purpose being
located at w on each side of the room and supplied with
the necessary tools and equipment. The cleaned parts of
each lamp are assembled at x, and passed through openings
or under the light partition ss to the benches yyj where
they are filled with oil drawn from the taps shown above
this bench. The lamp house is built of 13-inch brick
walls and a slate roof. The house is heated by steam from
the power plant. In a small brick addition is built a suit-
able oil tank n, having a capacity of about 150 gallons of
oil. The oil is pumped into this tank from barrels on the
outside of the building. The tank n is set at a sufficient

THE LAMP HOUSE

351

height to enable the oil to flow through the pipe s leading
from the bottom of the tank and supplying the taps for
filling the lamps. After filling, the lamps are removed
to the tables tt where the wicks are trimmed and new
wicks supplied if required ^^nd the lamps put together; or
the top of each lamp may be left off and set aw^ay with

Fig. 68. — Receiving Lamps at the Lamp House

the lamp in its proper place in the racks m. The racks
shown in the figure will accommodate 480 lamps; each
rack is 5 shelves high and each shelf contains places for a
dozen lamps. The boxes or pigeonholes are numbered with
numbei-s corresponding to the numbei-s on the lamps.
Each lamp after being cleaned and filled is returned to its
proper place in the rack, where it is readily found when
needed in the morning.

When applying for lamps the men enter and pass through
the passage e, receiving their lighted lamps at the windows

352 MINE GASES AND EXPLOSIONS

pp, in return for the numbered checks given them the
night before. Fig. 68 is a view of the interior of such
a lamp house, and shows the men going on shift in the
act of receiving and examining their lamps. Each lamp
is lighted quickly at a burning jet, screwed together and
locked by the attendant before being given out. The
floor of the lamp house is of cement, the tables and benches
are supported on iron frames or brackets and have slate
tops, the lamp racks are iron. The house should be
lighted with electric incandescent lamps. No one should
enter the lamp rooms, to which there is but one door, but
those who have been regularly appointed to have charge
of the work. The house should be kept absolutely clean
in all its appointments.

ADDENDA

STANDARDS OF WEIGHT AND MEASURE

No one can read the History of Standard Weights and
Measures of the United States, prepared and issued by the
Bureau of Standards, Washington, D. C, without being
deeply impressed with the importance of uniformity in all
standards in use throughout the world.

Unfortunately much confusion has attended each suc-
cessive attempt on the part of different countries to
establish a natural standard of reference such that its
value could be readily restored in the event of the loss of
the original standard.

The French or metric unit of length, the meter, was
intended to be one ten-millionth part of a meridian quad-
rant of the earth. Subsequent measurements, however,
showed not only that the meridians measured were of
unequal length, but the remeasurement of the meridian
selected previously by the French committee gave a
result that differed from the first measurement by about
iV of one per cent. This natural standard was therefore
abandoned.

The English unit of length, the so-called standard
imperial yard, was originally, by act of Parliament, made

353

354 MINE GASES AND EXPLOSIONS

derivable from the length of a simple seconds pendulum,
at sea level, London, which was stated as being 39.139

inches. The standard yard was therefore made '..^q

of the length of the above seconds pendulum.

However, the original British standard having been
rendered useless by the fire that destroyed the Houses of
Parliament (October, 1834), a n*ew standard was con-
structed by the committee having the work in charge
without reference to the legalized length of the seconds
pendulum. The length of the new standard was estab-
lished by comparisons with other standards, said to be
true copies of the original standard destroyed. Here
again the idea of a natural standard proved to be more a
sentiment than an actual reality.

Experience has proved that it is always possible to
gauge volume more closely by weighing than by the
most careful measurement. For this reason the volume
of a given weight of distilled water, at its maximum
density (4°C.) or at any other stated density, in a
vacuum or in air, etc., as the case may be, has been
found a convenient basis of comparison when estimating
weight or volume. Units of weight and of volume are
therefore quite generally expressed in terms of the weight
and volume of water under stated conditions.

Unfortunately for the securing of uniformity, the weight
of water has not been determined with great exactness,
and for this reason the unit weight assumed has differed
in different countries. This is apparent when comparing
the legal standards of Great Britain and France. For
example, in Great Britain the standard gallon is declared
to be 10 pounds of water at 62° F., weighed with brass
weights, in air at 62° F., barometer 30 inches, being in

STANDARDS OF WEIGHT AND MEASURE 355

volume 277.274 cubic inches. This volume of the gallon
Is based on an assumed weight of distilled water as follows :

1 cu. in. water, 4°C., in vacuum 253.000 grains.

1 ^' ^' '* 62° F., '' '' 252.724 ''

^ <c ic a 62°F., in air (62° F.,

bar. 30 in.), brass wts.. 252.458 "

Then, for the volume of 10 pounds of distilled water at
62° F., weighed with brass weights, in air at 62° F.,
barometer 30 inches, since 1. pound = 7,000 grains,

^,^ ' ^ =277.274 cu. in. (English standard gallon)

Comparing the above weight of 1 cubic inch of distilled
water, at maximum density (4° C), in vacuum, with the
assumed unit weight in the French system
1 liter (cu. decimeter) water, 4°C., in vacuum =15,432.36 grs.

In the English system (1 meter =39.37079 inches*); then
1 liter = 61 .02705 cubic inches, and the weight of 1 cubic
inch of water (4° C), in a vacuum, on the French basis, is

15,432.36 ^_ ^^^

The unit weight of water adopted by the French is
therefore lighter than that adopted by the English, for
the same conditions.

As far as the United States is concerned, the chief
importance attaches to the comparison of the English and
French standards, since the standards in common use in
this country have for the most part been brought from
England, and for the further reason that the French or

* The value of the English meter is sometimes given as 39.370113
inches.

356 MINE GASES AND EXPLOSIONS

metric system is coming into general use, and will eventually
be the basis of comparison for all standards, if not the
adopted standard in all countries.

The following are the units of length, weight, and volume
in common use in France, England, and the United States,
together with their equivalencies :

In England :

7 .o. . , X . 3,600,000 ,
The standard yard (36 mches) is o qo^ ^70 c>f a meter.

The pound avoirdupois (7,000 grains) =453.5924277

grams.
The standard gallon (277.274 cubic inches) = 4.54346

liters.

In France .

The meter ^39.37 inches (United States); 39.37079
inches (England).

The A;^•%ram = 2.204622341 pounds; 15,432.356387
grains.

The ^i^6r=. 2641 7 gallons (United States); .220097 gal-
lons (England).

In the United States :

The yard (36 inches) is :^-^ of a meter.

The pound avoirdupois (7,000 grains) =453.5924277
grams.

The gallon (231 cubic inches) =3.78543 liters.

The difference in the values given to the meter in the
United States and in Great Britain, each expressed in
inches, shows the United States inch to be slightly longer
than the English inch.

In connection with the comparison of standards, the

THE METRIC SYSTEM 357

density of distilled water at different temperatures is
important. Taking its density at 4°C. as unity or 1,
the relative density of distilled water at any temperature
is expressed by the formula

i,ooor

"5002+7^2'

in which
Z) = density of distilled water at T degrees absolute;
7" = absolute temperature of the water (deg. Fahr.)
For example, the density of water at 62° F., or an

absolute- temperature of 7^ = 460 + 62 = 522° is

^1,000X522^

5002 + 5222 -^^^^^^

The actual density at this temperature is .998908.
Likewise for the density at 212° F., or 7^ = 460 + 212 = 672°,

1,000X672

5002 + 6722 "-^^^^^

The actual density in this case is .95866. The error here,
though greater than before, is less than .09 per cent.

THE METRIC SYSTEM

The metric system as it is known to-day is practically
not different from the original French system of weights
and measures. The principal features of the metric
system were embodied in a report made by the Academy
of Sciences to the French National Assembly in 1791.
It was not, however, until fifty years later, in 1840, that
the use of the system became general in France. Other
countries later adopted the metric system as a standard or
permitted its use. In 1866 the use of the metric system
was made lawful in the United States by act of Congress.

358 MINE GASES AND EXPLOSIONS

The metric system is a decimal system, all multiples or
divisions of the adopted units being expressed in tens.
The principal unit or base of the system is the meter, being
the unit of length. The system now has no natural
standard, its length being defined and perpetuated by
certain artificial platinum and platinum-iridium standards
preserved in the Archives, at Paris, and in the vault of
the International Bureau of Weights and Measures, near
Paris, France.

The unit' of weight (mass) is the weight or mass of dis-
tilled water at maximum density whose volume is equal
to one cubic decimeter, the weighing being performed in
a vacuum in order to eliminate the buoyant effect of the
air, which varies with the temperature and atmospheric
pressure. This unit weight is called a kilogram, being
equal to one thousand grams.

The unit of capacity is the volume of the mass of one
kilogram of distilled water at its maximum density and
weighed in a vacuum. This unit volume is called a liter
and contains one thousand cubic centimeters.

Since 1 cubic centimeter of water weighs 1 gram, the
specific gravity of any substance, referred to water as unity,
is the weight per cubic centimeter of the substance in
grams, or the weight per liter in kilograms. For example,
the specific gravity of alcohol being .793, 1 liter of alcohol
weighs .793 kilograms; or, sulphuric acid having a specific
gravity of 1.75 weighs 1.75 kilograms per Hter, or 1.75
grams per cubic centimeter.

Since the establishment of the International Bureau of
Weights and Measures, May 20, 1875, much has been
accomplished towards securing more uniform and perma-
nent standards. By an agreement duly signed by seven-
teen of the principal governments, the International

THE METRIC SYSTEM 359

Bureau was located just outside of Paris, on a plat of
ground set aside for the purpose by the French govern-
ment and declared to be neutral ground.

New standards were made by the international com-
mittee, of an alloy consisting of 90 per cent, platinum
and 10 per cent, iridium, which were exact copies of the
meter and kilogram standards of the Archives, Paris.
Of these copies, the meter and kilogram that agreed most
closely with those of the Archives were deposited as the
international standards in a subterranean vault under one
of the buildings of the International Bureau. This vault
can only be opened when three officials are present, each
bearing a different key. The other standards were then
distributed to the several governments forming the
bureau, after all had been approved by a general con-
ference held at Paris, September, 1889.

FUNDAMENTAL EQUIVALENTS

(United States Legal Standards)

The following are given as the fundamental units and
equivalents of metric weights and measures by the American
Bureau of Standards, Washington, D. C.

Unit of length, meter =39-37 inches (United States).

Unit of capacity, liter =i cubic decimeter.

Unit of weight, gram = weight of i cubic centimeter of pure

water at maximum density (4° C.)
Gallon, U. S. (Winchester) =231 cubic inches.
Bushel, U. S. =2,150.42 cubic inches.

Pound (avoirdupois) =7,000 grains.

" " =453.5924277 grams.

Gram =15.432356387 grains.

Pound (troy, apothecaries) =5,760 grains.

The grain is the basis of comparison for avoirdupois,
troy, and apothecaries' weights, being the same in each.

360

MINE GASES AND EXPLOSIONS

CONVERSION TABLES

UNITED STATES AND METRIC WEIGHTS AND MEASURES

Linear

Inches X

25.40005 = millimeters

Millimeters X

.03937 = inches

'' X

2.54000= centimeters

Centimeters X

.39370= "

" X

.25400 = decimeters

Decimeters X

3.93700= "

" X

.02540= meters

Meters X

39.37000= "

Feet X

.30480= ''

3.28083 = feet

Yards X

.91440= "

1.09361 = yards

Rods X

5.02921= "

.19884 = rods

Miles X 1609.35000= "

.00062 = miles

" X

160.93500 = decameters

Decameters X

.00621= "

'' X

16.09350= hectometers

Hectometers X

.06213= ''

" X

1.60935 = kilometers

Kilometers X

.62137= "

Rods X

.00503 =

198.83838 = rods

Yards X

.00091 =

Xl093.61111 = yards

Feet X

.00030 =

X 3280.83333 = feet

Miles X

. 16093 = myriameters

Myriameters X

6.21370= miles

Square

Inches X

" X

Feet X

'' X

Yards X

" X

Rods X

Acres

Miles

645. 16254 = millimeters
6.45163 = centimeters
929.03406 =

9.29034 = decimeters
83.61307 =

.83613 = meters
25.29295= "
X 4046.87235= "
X .40469 = hectares
X 258.99983= "

Millimeters X

Centimeters X

Decimeters X

Meters X

Hectares X

.00155 = inches
.15500= "

15.49997= "
.10764 = feet

10.76387= "

1.19599 = yards

.03954 = rods

.00025= acres

2.47104= "■

.00386 = miles

Cubic

InchesX 16.38716 = centimeters

Feet X 28.31702 = decimeters

'* X .02832 = meters

Yards X .76456= ' '

Centimeters X

Decimeters X

Meters X

.06102 = inches
61.02338= ''
35.3 1445 = feet
1.30794= yards

CONVERSION TABLES

361

Capacity

Cu. inches X 16.38716 = milliliters

'' '' X 1.63872 = centiliters

'' " X .16387 = deciliters

" " X .01639 = liters

Cu. feet X28.31702= ''

" " X 2.83170 = decaliters

" '' X .28317 = hectoliters

'' '' X .02832 = kiloliters

Milliliters X .06102 = cu. inches
CentiUters X .61023 =
Deciliters X 6.10234 =
Liters X 61.02338 =

X .0353 l = cu feet
Decaliters X .35314 =
Hectoliters X 3.53145 =
Kiloliters X 35.31446=

Liquid Measure — U. S.

Minims
Fluid dr.
Fluid oz.
Gills
Pints
Quarts
Gallons
Barrels

X .06161 =
X 3.69671 =

X 2.95737 =

XI 1.82948 =
X 4.73179 =
X .94636 =
X 3.78543 =
X 11.92412 =
X 1.19241 =

= milliliters

= centihters

= deciliters
= liters

-- decaliters

Millihters X 16.23060 = minims

Centiliters X 2.70510= fluid dr.

Deciliters X 3.38138 = fluid oz.

Liters X 8.45344 = gills

X 2.11336 = pmts

X 1.05668 = quarts

X .26417 = gallons

Decanters X .08386 = barrels

hectoUters Hectoliters X .83863 =

Dry Measure — ^U. S.

Pints X .55061 = liters
Quarts X 1.10123= "
Pecks X 8.80982= ''
Bushels X .35239 = hectoliters

Liters Xl.81616 = pints
'' X .90808 = quarts

'' X .11351 = pecks

HectoHters X 2.83774 = bushels

Avoirdupois

Drams X 1.77184 = grams
Ounces X 2.83495 = decagrams
Pounds X 4.53592 = hectograms

Decagrams X 5.64382 = drams
Hectograms X 3.52739 = ounces
Kilograms X 2.20462 = pounds

Apothecaries

Grains X 6.47989 = centigrams
Scruples X 12.95978 = decigrams
Drams X 3.88794= grams
Ounces X 3. 11035 = decagrams
Pounds X 3.73242 = hectograms

Grams X 15.43236 = grains

Decagrams X 7.71618 = scruples

X 2.57206 = drams
Hectograms X 3.21 508 = ounces
Kilograms X 2.67923 = pounds

Troy

Grains X 6.47989 =
Pennywts.X 15.55174 =
Ounces X 3 1.10347 =
Pounds X 37.32418 =

= centigrams
= decigrams
= grams
= decagrams

Grams X 15.43236 = grains

Decagrams X 6.43015 = pennywts
Hectograms X 3.21508 = ounces
Kilograms X 2.67923 = pounds

362 MINE GASES AND EXPLOSIONS

CONSTANTS AND UNITS OF REFERENCE

Aside from uniformity of standards, it is apparent to
all engineers and students of science that similar uni-
formity and accuracy are needed in respect to the numerous
constants and reference units employed in all scientific
calculations. Not only is this desirable but absolutely
essential in order that true progress shall be made. Much
confusion often arises in comparing notes referred to
different standards, which would be in large part or wholly
avoided by the use of generally accepted constants or
equivalents.

As far as possible the constants used in this volume are
those that have been most generally accepted. The
determinations of the weight of air and the densities of
gases by Regnault; the pressure of the atmosphere at
different elevations above sea level, by Airy; the aeronautic
observations of Gay-Lussac, Glaisher, and Herschel; the
heat determinations of Regnault, and Favre and Silber-
mann, have all furnished reliable data for the calculation
of these constants.

The weights of unit volumes of the common standards,
water, air, hydrogen, and mercury, are given in grams,
pounds, and grains, in the table on the opposite page.

It has been the aim throughout to make all values and
constants used correspondent, or such as are derivable
from each other. For example, the weight of 1 cubic inch
of water (4°C.) being .03613 pound, and the specific
gravity of mercury (32° F., standard) being 13.593, the
weight of 1 cubic anch of mercury (32° F.) is

.03613X13.593 = 491 1 1 lb.

CONSTANTS AND UNITS OF REFERENCE

363

Again, the normal barometric reading at sea level being
29.925 inches of mercury (Table 7), the corresponding
atmospheric pressure is

.49111 X29.925= 14.696 lb. per sq. in.

Volume

Weight

Grams

Pounds

Grains

Water (max. dens., 4°C.),

standard

Do., calculated

Do., "

Water (freezing, 0° C),

calculated

Water (normal, 62° F.),

calculated

Mercury (32° F., sp. gr.

13.593)

Do., calculated

Air (dry, 0° C, 760 mm.),

Regnault ,

Air (dry, 32° F., 29.92 in.),

calculated

Air (dry, 60° F., 30 in.),

calculated

Hydrogen (0° C, 760 mm.),

Regnaiilt

Hydrogen (32° F., 29.92 in.),

calculated

1 liter
1 cu. in,
1 cu. ft.

1 liter

1 ''

1 cu. in.
1 cu. ft.

I liter
1 cu. ft
1 cu. ft

I liter
1 cu. ft

1,000.00

16.39

28,317.01

999.97

998.91

222.76

1. 293 1 87

36.617

34.738

.089578

2.536

2.20462

.03613

62.42830

2.20456

2.20222

.49111
848.58790

.002851

.080728

.076585

.005592

15,432.36

252.89

436,998.10

15,431.95

15,415.50

3,437.77

19.957
565.096
536.095
1.382400
39.144

INDEX

Note. — Numbers refer to pages. Letters used as abbreviations relate to words
in the same line, or in the title or heading under which they stand.

Abandoned workings,
danger of, 191
draining gas from, 191
gas in, 117, 120, 191, 204
roof falls in, 205
spontaneous combustion in, 155
ventilation of, 191
Absolute pressure, air and gas, 57
p. above vacuum, 58
relation to a. temperature, 57
adiabatic, 60

volume, 58

adiabatic, 39, 60, 214
Absolute temperature, 54
calculation of, 55
relation to a. pressure, 57
adiabatic, 60

— volume, 55

adiabatic, 60
Absolute zero, 54
Absorption of oxygen by coal and

dust, 154
Absorptive power of air and gases,

150
Accidents in mines,
causes of, 258
(See Blasting)
(See Explosions, mine)
commission, See C.
explosions, See E.
fatality of, 174, 180, 190, 203

by afterdamp, 145, 180, 182, 187

— dust, 176

— gas, 217

— mine explo.sions, 189, 209, 217,
344

depends on, 191
.small proportion reported, 190
table showing, 189, 209
Accumulation of gas, 1 15, 181
causes of, 114, 115, 191
conditions affecting, 114, 115,

122
how avoided, 191, 192, 201
in abandoned places, SreA.etc.
— rise workings, 123

Accumulation, etc., continued
- roof, 121, 204, 346
—pockets, 120, 346
—the strata, 116, 117, 120
nitrogen, 113
Acetylene gas in mine lamps, 292
dangerous, expensive, 293
how generated, 293
illuminating power of, 293
not easily extinguished, 293
Adhesion, Force of, 9
Adiabatic,

compression of air or gas, 39, 60
expansion of air or gas, 39, 60
formulas, 40, 60, 61
Affinity, Force of, 4, 9
Afterdamp, 129

carbon monoxide, percentage
of, 130
reduced from carbon dioxide, 131,
144, 174. (See C.)
composition of, 129, 131, 132,

179
danger of, 181
effect on,
animals, 143

an exhausted condition, 179
a strong man, 182
strong and weak persons, 142, 144
young and old persons, 142

escape from, 180, 187
hydrogen in, 114, 128, 131
instantly fatal, 145, 174
most dangerous, 131
removal of, after exj)losion, 181
victims, large percentage of, 180
Air, (See Mine a.)
composition of,

by volume, 75

— weight, 75.

depletion of oxygen. See O.
dilution with gases, 143, 289
effect of cold and pressure, 6

compression, sparks,

172

365

366

INDEX

Air, continued

expansion and compression of.

(See E.)
fluid, a, 79

fresh, impure, bad a., 134
humidity of, See Saturation,
hygrometric condition, 92, 206

relation to explosion, 164, 193
moist a.,

lighter than dry a.. 93
weight of, formula, 94

moisture in, 92, 193. (See Mine

a.),
air never dry, 92, 193
effect of seasons, 92
on density, pressure of a.,

93
measurement of, 96-98
weight of, formula, 94.
properties of, - —

absorptive power, 150
compressibility. 11; density, 31;

diffusion, 13; elasticity, 12;

expansion, 54; — adiabatic e.,

60; pressure (tension), 12;

viscosity, 12; weight, 14
regeneration of expired a., 185

alkali required, 186
difficulty of, 186

respiration of a.

essential principles, 186
quantity per minute, 184, 185

saturation of a., 92. (See moist-
ure in.)

effect on density, 93

of temperature, 92

laws of, 93
sparks by rapid compression of

a., 172
specific heat of, (table), 49
standard for gases, 23
supply of air in rescue work,

breathing apparatus, 183, 184
(See B. a.)

drill holes, 188

pipe lines, 187
vapor in a., See moisture in a.
vitalizing power of, 184
weight of, 75

effect of elevation, 88

gravity, 75

— moisture, 93

formulas, 76, 77, 94

how determined, 75

standard, 75, 91, 363

Air-current.

arrest of , by blast, 198, 203
conducting,

means of, 181

to sweep cavities and voids, 191
cold intakes, danger of, 207
conveys moisture, 207

Air-current, continued
effect of,

blasting, 198, 203
evaporation of water, 53
explosion, 180, 198
natural heat of mine, 207
"end of tlie air," 202
"last of the air," 202
make no advance ahead of, 181
purpose of, or agency, 1
reversed by explosion, 180
restoring, after explosion, 181
steam exhaust in intake, 207
velocity of, desired, 191, 202
water, weight of, home on, 207
Air-lock, automatic, 245, 281, 286

superior to magnet lock, 287
Airways (mine),

deposit of moisture in, 92
effect of restricted a.-^thin
seams, 212
Alcohol, See Illuminants, (spec-
ial).
Alcohol flame. See F. (a.)
Alcohol lamps, 230, 257, 262
Ashworth, 250, 269
Chesneau, 265, 269
Pieler, 262
Stokes, 267
flame easily extinguished, 264,

272, 336
hydrogen, compared, 272
Aluminum in lamps, 220
Ammonite, 200
Aneroid barometer, The, 83

compensated for temperature

changes, 84
construction of, 83-85
corrected to give standard read-
ings, 90
mining, The, 85
purpose of, 86
range of readings limited, 8
scale of, 84, 85
Animal oils, 294

compared with mineral o., 298
flashing point safe, 296
kinds of,
fish o., 294
lard o.. See L. o.
seal o.. See S. o.
sperm o., See S. o.
whale o., 294
mixed with petroleum, See P.,

etc.
sources of, 294

INDEX

367

Animals, more sensitive to gas,
143
canary birds used to detect gas,

107
mice and rats in mines, 107
mouse test for whitedamp, 106,
143, 182
Anions, 6
Anthracite dust,

effect on explosive conditions of
air, 344
Aqueous vapor, See V.
Archimedes, Principle of, 17
Ashworth bonnet, 249
Ashworth-Hepple white-Gray
lamp, 252
Beard-Mackie A-H-G lamp, 273
Clowes A-H-G lamp, 270
illuminating power, 256, 306
oil burned, 256
perfection of, 254
resistance to current velocity,

256
short-pattern lamp, 252
standard lamp, 256
Stokes A-H-G lamp, 267
testing for gas, manner of, 254
Ashworth lamp. The, 250
distinctive features, 250, 251
illuminant used, 251
oil vessels, three, 251, 252
Ashworth shield, 274
Ashworth tester, The, 269
Atmosphere, The, 74
composition of, 74

carbon dioxide, per cent, of, 132

less at surface, 132

in mine air, 132.

constancy of, 126
differs from mine air, 132
in London, 126

pressure of, See Atmospheric

pressure,
temperature of,

average for air-columns, 89

causes affecting, 87

observed at different elevations,

89
rate of fall per 1,000 ft. ascent, 89

Atmosphere (mine),

(See Explosive conditions)
(See Gaseous conditions)
(See Mine air)
(See Mine conditions)

dangerous a., 141

classified, 136

causes producing 141, 334, 344

Atmosphere (mine), continued
dry a., safety of, 193
effect of burning bad oil, 133

— dust, See Coal d.

— moisture. See Mine a.

— temperature, See M.

conditions.

explosive a., 136. (See E. c.)
classified, 136
effect of dust, 138

— gas, 135-137

least per cent, of gas required, 137,
344

extinctive a., 138. (See E. a.,
etc.)
classified, 136
effect on flames, 139-141
flame, firedamp, 140

■ lamps, gas- fed, 140

wick-fed, 140

residual vs. artificial, 140
respirable, 110, 144
safe to withdraw from, 110
types of, 138, 139

fatal a., 143

classified, 136

composition of, 144

instantly f., 145, 174

per cent, carbon dioxide, 110, 144

monoxide, 106.

142, 144.
per cent, hydrogen sulphide, 144

methane, 144

nitrogen, 144

types of, irrespirable, poisonous,

143

irrespirable a., 110, 143

lamps burn in, 110 144, 182

safety of, See M. conditions.
Atmospheres, Measurement of

pressure in, 91, 116
Atmospheric conditions, (See Bar-
ometric changes. )
relation of, to mine explosions,
204-207
Atmospheric pressure, 78

amount at different elevations,

86,88
amount at sea level, 78, 88
cause of, 78
effect on transpiration of gas,

205
experiment showing, 79
fluctuation of,

daily, 78
irregular, 79
yearly, 78
measurement of, (See Barome-
ter.)

calculation, formula, 87
mercury column, 81, 86

368

INDEX

Atom, defined, 7; weight of, 14
Atomic theory, 5

Dalton's, 10, 14
Atomic volume, 15

law of (Avogadro's), 15
Atomic weight, 14

difference between a. w. and
specific gravity, 22

table of, 8

imit of, 15
Attraction,

between liquids and solids, 12

capillary a., 12

forces of, 9

of the earth, See Gravita-
tion.
Austrian firedamp commission,
169

appointed, when, 169

experiments of, 170

summary and date of report,
170
Authorities quoted, iv, 362

Ybel,63, 152, 166, 173, 205, 254

Airy, 362

Aitken, 309

Ansell, 309

Ashworth, 147, 166, 173, 192,
193 225 254

Atkinson, 154, 166, 173, 177

Avogadro, 15

Bald, 164

Becquerel, 152

Bedson, 155

Bella, 315

Berthelot, 153

Berzelius, 197

Boyle, 59

Broockmann, 173

Buddie, 164

Bunsen, 152, 290

Carlton, 315

Chaloner, 315

Charles, 54

Chesneau, 265

Clanny, 217, 219

Clowes, 138, 139, 140, 334, 337

Coquillion, 308

Dalton, 5, 10. 14

Davy, 148,218,219,225

Dickinson, 172, 173

Dixon, 149, 161

Duggan, 315

Authorities quoted, continued
Dulong, 70
Evan, 237
Faraday, 165, 177
Favre, 65, 362
Fayal, 155
Forbes, 313
Fost(»r, 316
Galloway, 134, 137, 138, 166,

327, 333, 344
Garforth, 313
Gay Lussac, 54, 89, 362
Glaisher, 89, 362
Haldane, 106, 107, 142, 180, 186
Hall, 138, 166, 167, 168, 192,

344
Herschel, 89, 362
Hughes, 237
Joule, 42

LeChatelier, 168, 266
Lewes, 152, 154
Libin, 309
Liveing, 310
Lvell, 165, 177
Mackie, 324
Mallard, 168, 266
Mariotte, 59
Maurice, 308
Meyer, 183, 184, 185
Molas, 315
Monnier, 308
Noble, 63
Pieler, 264
Reece, 315
Regnault, 50, 52, 54, 75, 184,

362
Rumford, 290
Sawyer, 205
Schwann, 184
Shaw, 315
Silbermann, 65, 362
Smith, Angus, 75, 132, 133, 134,

172, 309, 310
Smith, J. Lorrain, 186
Stephenson, 219
Stokes, 267, 297
Thomas, 109, 130, 132, 139
Vital, 138
Wheatstone, 290
Zuntz, 184
Avogadro's law of gaseous vol-
umes, 15

application of, 30, 36

INDEX

369

Balance,

hydrostatic, The, 17

specific gravity determined by,
18
Barium, Hydrated peroxide, 185
Barometer, The,

aneroid. See A.

effect of sudden fall of, 205

need of observing, 205

mercurial, 80

adjustment of, 82
construction, 81, 82
principle, 80, 81

purpose, 80

use of, 85
Barometric changes. (See Atmos-
pheric pressure.)

cause roof falls, 205

relation to mine explosions, 204-
206

sudden fall of barometer, 204
Barometric pressure. (See Atmos-
pheric pressure. )

high b. p. danger of, 205

meaning of, 83
Barometric readings,

at different elevations, 86

calculation of, formula, 87

correction of, 83

effect of —

gravity, 90
temperature , 83

standard, 83, 86, 91

table of, for different elevations,

88
Baume hydrometer, 21
Beard deputy lamp, 257
Eloin-Marsaut type, 257
illuminating power, 258
resistance to current velocity,

258
sight test for gas, 258
Beard-Mackie lamps, 273
accurate sight test, 274
detectsone-half percent, change,

274
good circulation in lamp, 273
scale measurement of gas, 338
Beard-Mackie sight indicator, 324
accuracy of, 258, 274, 329
advantages of, 329, 343
calibration of. (See C.)

Beard-Mackie s. i. , continued
detects,

small percentages of gas, 230, 274,

325. 329, 344
slight gaseous changes, 258, 329,

343
gas on normal working flame. 258^
329, 330, 338, 343

effect of burning bad oil, 345

experiments with, 326

indicates approach to gas, 343

in lamps,

A-H-G. lamp, 273
Beard deputy lamp, 257
Davy lamp, 326

observations with, 344
principle of, 325

differs from Liveing indicator, 326
range of test, 274, 325, 329
sight indication, a constant,

258, 274, 329, 343
use of, 343
used first, when, 324
wires,

enable lamp to hold its flame, 325

glow above tip of flame, 326, 338

incandescence of, 258, 274, 325.
330

looped percentage w., 258, 274, 324

sooting of, 345

standard wire, purpose of, 324

Beaum6 hydrometer, See Baume h.
Behavior of mine gases, The, 114

(See Gases, mine)
Belgian Mueseler lamp, 260
compared with English Mues-
eler, 259
superior, 260
dimensions of, 260
illuminating power, 306
legalized in Belgium, 260
resistance to current velocity,

260
tested by Accidents commission,
260
Benzine, distilled from petroleum,
295
temperature of distillation, 295.
Benzine, naphtha, See Illumi-

nants. )
Benzoline, 257, 295, 335
Birds, use of. to detect gas, 107
Bituminous mining laws prohibit,
Clanny, unbonneted, 243
Davy, for general use, 236
Bituminous matter in coal, 116,
147
vaporization of , 147.

370

INDEX

Blackdamp, See Carbon dioxide.
Black blasting powder, (See Gun-
powder)

best for coal, 199

composition, See G.

heat energy per pound, 152

explosion of,

chemical reaction variable, 63

flame produced, 105, 199

keg of p., 137, 196

projected incandescent particles,

201
temperature of, 154, 200
volume of gases produced, 153

heat energy per pound, 152
unsafe in gas, 199
Blasting gelatine, 200
Blasting in mines,
accidents due to,

explosion of keg of powder, 137,

196
ignorance and carelessness, 196
slowing fan at firing time, 203

blown-out shots, See s. b. o.
charging the hole,

excessive charge, 198

stemming, 202

tamping, 202

circulation of air, See C. in

mines,
coal powdered by blast, 201
dangers of, 196-199. (See Ac-
cidents)

cold air-current, 207
contracted openings, 197
dust and gas, 197
placing shots wrongly, 198
to minimize, 201

explosives used, See E.

(See Powders)

safe in gas, attempts to make, 199

firing,

electric, 201

incandescent particles projected,

201
order of, 202
use of hot wire, 201

fuse and squibs, 201

touchpaper, 201

precautions, 201

relation to mine explosions, 196-

204
shot blows tamping, 197-8
shots, blown-out, 197

action of, 197

danger of, 137

ignition of dust, 138, 169, 174

gas, 158

volume and intensity of flame
138, 197

Blasting in mines, continued
shots, position of,

facing air-current, 198

another s.. 198

, rapid succession of, 198

, windy, 137, 198

differs from blown-out s., 198

temperature of air normal, 202
watering before firing, 192-4
Blood-test for carbon monoxide,

107
Blowers (gas). Mine, 120. (See
Feeders)
composition of gases from, 103
Killingworth colliery b., 239
formation of, 120
Blown-out shot, 197

(See Blasting, etc.)
Boiling, evaporation, (See E.)

difference between, 53
Boiling point, 6

a fixed point, for a given pres-
sure, 53
effect of pressure on, 6
water, of, 53

use in graduating thermometer,
42, 43

Bonnets (safety-lamps ) ,
Ashworth, The, 249
corrugated, 274
double, 250, 252
effect of,

on circulation in lamp, 224, 232,
273

— illumination, 298

— security, 223

— testing flame, 273

locked by movable standard,

245
openings in, 243

deflecting the entering air, 242,

249, 278
intake and discharge, 249, 250
restricted, 247
tangential, 242, 275

purpose of, 222-3

Bore holes, for draining gas, 121,
192. (See Drill holes)

Bottle, specific gravity, 19

Boyle's law of gases, 59

Brass in lamps, 220

Breathing apparatus, See Rescue
work, etc.

British thermal unit, 47
mechanical equivalent, 48
per pound of combustible, 65

INDEX

371

British thermal unit, continued
specific heat, expressed as, 49
value of,

in foot-pound, 48
— horsepower, 48

Brushes,

lamp b., 339

on electric machines,

carbon V8. copper, 159
ignition of gas, 159
sparking of, 159, 196

Bull's eye (Ma^ chline) lamp, 245

surveyor's lamp, 246
Bumps, 117

cause of, 117

often last several days, 121

precede outbursts of gas, 121

warning to the miner, 121
Bunsen's photometer, 291

principle of, 292

scale, formula to calculate, 292

Calibration of,

Beard-Mackie sight indicator,
327

difficulties met, 328

standard wire, selecting, 328, 329

experiments previous, 326

Bunsen's photometer,

formula for calculating scale, 292
Calorie (French heat unit), 47
Calorific power (Heat value), 69
table of c. p. of various sub-
stances, 65
Dulong's formula for calcu-
lating, 70
Cambrian lamp, 245
Candles, 290

compared with oils, 296
composite c, See C. c.
difi"erent kinds, 290
extinction of, 139

table extinctive atmospheres, 140
illuminating power of, 290
standard c. (light unit), 290,

297
use of, in mines, 215
wax c, See W. c.
weight of, 290
wicks See W. c.
Candle flame, See F. (c.)
Candle power, 290

Cap, See Flame c.
Capillary action (attraction), 12
Carbide of barium, 293
Carbon brushes (electric), See B.
Carbon dioxide (blackaamp), 109
absorptive power, 150
artificial atmosphere of, 139,

140
density, 3
detection of, 110
diffusion, rate of, 124
effect on —

firedamp, 104, 127

flame. 109, 110

flame cap in testing for gas, 127

human system, 109, 110, 143, 186

respiration, 186

extinctive effect of, 109, 110,
139
per cent, extinctive, 110, 140
in the atmosphere, See A.

— expired air, 186

— mine air, (See M. a.)

difficult to remove, 123
feeders in roof, 122, 123, 127
how produced, 109
reduced to CO by carbon (dust)
131, 144, 174

per cent, fatal, 110, 144
poisonous action of , 110, 143
properties of, 109
specific gravity of, 3, 49, 124
specific heat, 49
transpiration, rate of, 119
treatment of persons overcome
by, 110
Carbonic acid gas. See Carbon

dioxide.
Carbonic oxide gas. See Carbon

monoxide.
Carbonite, 200

Carbon monoxide (whitedamp),
105
absorption in blood, 106, 107,

108
combustion of, 38. (See ex-
plosion of)

change of volume, 38
chemical reaction, 38, 213
energy developed, 152
heat of c. in oxygen, 65

nitrous oxide, 113

pressure reduced, 39, 213
temperature, 68, 154, 163. 213.

214
volume of gaseous products, 154

danger of, 137, 142

372

INDEX

Carbon monoxide, continued^
detection of,

bird test, 107

blood test, 107

flame test, 104

mouse test, 106, 143, 182
diffusion, rate of, 124
effect on —

animals: birds, 107; mouse, 107,

143, 182; rats and mice, 107
firedamp, 104. 141
flame, 106
flame cap, 104

human system, 106, 143. (See
poisonous action)

explosion of, 213. (See com-
bustion of)
calculation of, 213. 214
change of volume, 213
pressure due to, 214

reduced, 213

temperature due to, 213, 214

explosive limits, 108, 137
flame temperature, 69

calculated, 69, 151

estimated, 151

ignition in dry air, 148

temperature of, 149

occurrence in mines,

chief product of dust explosion,

163
component of afterdamp. See A.
distilled from coal dust, 105. (See

CD.)
formed by gob fires, 105, 155
produces flame in blasting, 105
reduced from CO2 by carbon
(dust), 131, 144, 174

poisonous action of, 108
most fatal when, 106, 142
percentage fatal, 106, 142, 144
strong and weak, 142, 144, 182
symptoms of p., 108, 142, 182
young and old, 142

properties of, 105
specific gravity of, 3, 49, 124
specific heat, 49
temperature of ignition, 149
transpiration, rate of, 119
treatment of persons overcome
by, 109, 182

Carbureted hydrogen, See Met-
hane.

Catalysis, 197

Catalytic action of dust, 171, 173,
197

Cation, 6

Caustic soda, 185, 186

Centigrade scale, 42

Chalk dust, 173

Charles' law of gases, See Gay

Lussac's 1.
Chemical change,

action of platinum to induce,
325

heat evolved, 39, 154
Chemical equation, 27

to write, 28

use of, 29
Chemical formulas, 26

use of, 29
Chemical heat, 39, 45, 69, 154
Chemical reaction, 25

cause of, 27

change of volume due to, 36

definition of, 7

determined by conditions, 65

expressed how, 25
Chemistry,

defined, 4

of gases, 4

questions in, 41
Chesneau lamp, The, 265

burns alcohol, 265

differs from Pieler, how, 267
safer than, 265

heats in gas, cools quickly, 267

resistance to current velocity,
266

scale measurement of gas, 266,
338

useless when hot, 267
Chimney, Lamp, (See Gauzes)

admission of air through —
double bonnet, 250
lower part of gauze, 241, 259

Protected openings, 231, 266, 278
elow the flame, 228, 231, 273

conical gauze. See G.
conical glass, See G.
conical sheet-iron (Mueseler),
259

dimensions of, 260

effect of, 232

extinctive effect of, 224

filled with flame, 224

gauze c, 222, 240. (See G.)

double, 228
protection of, 222, 232
surrounded by glass, 236, 238

glass c, See G.
Chokedamp, 109. (See Carbon
dioxide)

INDEX

373

Circulation in lamp, 227
ascensional, 230
condition due to free c, 222

explosions in lamp, 223

flaming, 222, 235

same inside as outside, 227, 235,

273, 333
sensitive to gas, 222, 235
free c, secured, how, 228
improves illumination, 230
restricted by chimney, 224, 292
restricted c, reduces —
height of flame cap, 332, 338
illumination, 297, 298
reversed by canting, 232, 252
Circulation in mines, 1

effect produced by explosion,

180
ideal condition in blasting, 202
need of ample and efficient c,

191, 202
reducing c. before firing, 202-
204, 206
practical effect, 203
reasons advanced, 203

restoring c. after explosion,

181
safest atmosphere for blasting,
193
Clanny lamp, The, 240

illuminatmg power, 243, 306
oil burned, 241
original lamp, 217, 221
prohibited by law, unbonneted,

243
resistance to current velocity,
242
Clowes hydrogen lamp, 270, 337
cylinder of, 271-272
capacity, 272
charge, atmospheres, 272

lasts 2 hours, 272

pressure of charge, 272

tested, 272

making a test, 338

number of tests to one charge,

272
range of tests, 272, 338
scale to measure flame cap, 337
weight of lamp, 272
Coal,

absorption of gases, 116
anthracite, 344
gases evolved from, 102
volume per 100 grams, 102

ton, 110

inflammable, 155, 169, 192, 201,
212, 344

Coal dust, (See D.;

absorption of oxygen by, 154,

156, 173, 174
character of dust important,

141, 164, 173, 178
coked, (See Coking, etc.)

character of coke, 165, 177, 178
deposited on face of timbers,
away from blast, 177
on either side, 178
towards blast, 165, 177
thickness deposited, 165, 176

. distils gas, 105, 171, 197
effect of c. d. on —

firedamp, 105, 141, 201, 225
flame cap, 344

explosive condition of air, See
E. c.

effect of extinctive gases, 171

inflammable gases, 171

explosion of, (See D. e. )
energy of, 152, 196
temperature of, 66, 154
volume of gaseous products, 154

explosive, (See E. conditions.)
absence of gas, 138, 168, 169, 170,

197, 344
anthracite d., 344
least percentage, 137, 344

formation of, in mines, 192
history of, 164
ignition of, by —

incandescent lamps, 156

naked lamps, 168, 171

effect of gas on, 138, 170, 171, 197

temperature of» 155, 158

inflammability depends on, 173
catalytic action of d., See C, etc.
character of C, 141, 164
fineness of d., 141, 164
moisture in air, 164
porosity (absorptive power), 164,

173
suspension of d. in air. 164

propagates flame, 169, 175.
reduces CO2 to CO, 131, 144,

174
removal of, 192

suspended in air, 66, 153, 164,
171, 173, 174
Coal dust theory, 171
history of, 164
rejected by French commission,

168-9
supported by, 134, 166
Coal oil, 295. 296, 301, 340. (See

Petroleum)
Cohesion, 9

374

INDEX

Coking of dust, 165, 177, 178. (See
Coal dust)
evidence of,

direction of blast, 165, 177
heat and little air, 178
process of, 178
depends on, 178
Cold seasons,

relation to mine explosions, 206
Colliery warnings, 205
Colzaline, first used, 295
Colza oil,

experiments with, 299
mixed with petroleum, See P.
etc.
Combustibles,

all c. explosive, 153
heat energies of, 152, 196
Combustion, 62. (See Spontane-
ous c.)
forms of, 62-3.
heat of, 65; always constant,

66
heat and air (oxygen) necessary,

62, 175
products of, 63
slow c, 62, 105
temperature of, 66. (See T.)
theory of, 62
Commissions, 168, 188, 190
accidents in Mines c,
date, 169

experiments, 169. 199, 298
report summarized, 169
work, conclusions, results^ 260,
298, 299, 307

Austrian c, date and work, 169,

170
French Firedamp c, 168, 265
Prussian Firedamp c, 169

experiments and conclusions, 169

Royal Coal Dust c,
date, 170

evidence before, 172
experiments for, 138, 149. 166
reported conclusions, 138, 170

Composite candles,

illuminating power, 290, 297

weight burned per hour, 297
Composition of gases,

percentage by volume, 34, 128

percentage by weight, 32
Compound substance, 7

chemical, 7

stable, 9, 28

unstable, 28

Compressed oxygen, 185
Compressibility, 11

relation to porosity, 11
Compression of air, (See Pressure.)
effect on —

heat capacity of air, 59
ignition of gas, 150, 172

relation to temperature, 59
sparks caused by, 172
Concussion of air, in mines,
(See Mine Air)
caused by blasting, 198
effect of, 131, 141"; 176
Conditions,

in mines 1. (See M. C.)
— lamps, 222. (See Circulation
inl.)
Conduction of heat, 46
Conductivity of matter, 13
Constants used should be —
accurate and uniform, 362
derivable from each other, 362
expressing unit weights of com-
mon standards, 3d3
Convection, 46

Copper brushes (electrical), See B.
Copper gauzes (lamp), See G.
Cotton in oil vessels, 264, 266, 277,
286, 296
absorbs illuminant, 264, 278,

296
Chesneau and Pieler lamps com-
pared, 266
cylindrical c. spreader, 277
flame cap, reduces height of,

264, 266
illumination impaired by old c,

279
renew often, 279
specially prepared, 277, 296
weight of c. in lamp, 277
Cul de sac, in mines, 175, 196
Cut-off plate, A-H-G lamp, 256

Dalton's atomic theory, 5, 10, 14
Dangerous atmosphere, A, See A.
Dangerous practices. See P.

INDEX

375

Davy lamp, 234. (See Safety
lamps)
circulation free, 235, 332, 333
dangerous for common use, 235
flames readily, 235

per cent, of gas present, 347
history of. See Safety 1. h.
illuminating power, 235-236,

306
prohibited by law, for general

work, 236, 330
resistance to current velocity,

235
sight indicator in, 326
testing for gas,

best form of lamp, 235, 333
manner of, 341

types of,

Davy in case, 236
Davy jack. 236
Davy with shield, 236, 237
fire boss Davy, 235
fireman's, 236
firetryer's, 236
gas finder's, 236
Jack Davy, 236
Newcastle, 236
pocket Davy, 235
Scotch Davy, See S. D.
tin-can Davy, 235, 236

Deflector in lamps, 243-4
Density, 5, 11
air,

at different elevations, 88
calculation of, 31
effect of atmospheric pressure, 86
referred to hydrogen, 31

gases (table), 3

calculation of, 30

relation to —

atomic weight, 15
diffusion, 123-4
specific gravity, 16

water (distilled),

calculation of, formula, 357
different temperatures, 357
unit weights of, 363

Depletion of oxygen in air. See

O.
Detonating explosives. See E.
Diffusion, 13

differs from mixing, how, 122

effect of —

gravity of the gas, 122
motion of the air or gas, 122

gases, 121

rate of (table), 124

methane in mines, 100, 123, 125

Diffusion, continue I

produces mixtures of exact pro-
portions, 122, 125

relation to density, 123-4

theory of, 121
Dilution of,

air in mines, 143, 288

gas in mines, 125

prevents ignition of gas, 100
Dissociation (of atoms), 3,9, 151-2
Drill holes (bore holes) for —

draining gas from roof, 121

workings, 192

supply of air and food, 188
Dust, (See Coal D.)

impregnated with oil, 174

incombustible d.,

catalytic action of, 171, 173, 197
causes explosion of gas, 171, 173,

197
effect on ignition of gas, 198

raised by operations of mine,

192 193
character of, 141, 164, 173, 178
"lower" and "upper" d., 173

Dust explosion, See E,, d.
Dusty mines,

adverse conditions in, 299
volatile oils, dangerous, 299
Dynamite, 200. (See Nitrogly-
cerin)
gas feeders extinguished by,

157
temperature of explosion, 200

Early practices re gas. See P., E.
Earth breathings, 208
Effusion of gases, 117. (See Emis-
sion)
Elasticity (of matter), 12
Electrical division of matter, 6
Electricity in mines, 196
e. firing (blasting), 201

- fuses burning out, 196

- lamps. See Incandescent 1.
breaking of, 159-160, 196
ignition of dust, 156
ignition of gas, 159-160
voltage, low vs high, 159-160

sparking of,

e. brushes, See B.
- wires, 158, 196

376

INDEX

Electric lamps, See Incandescent 1.
Elements, 7

atomic weights and symbols
(table), 8
Elementary matter, 7
Elevations above sea level (table),
88
atmospheric,

pressure. (See A. P.)
temperature, (table), 89

barometer readings, See B. R.
weight (density) of air (table),

88. (See D.)
Eloin lamps,

arrangement of, 231

condition same inside as outside,

333
flame cap conforms closer to

law, 332
multiple gauzes required, 248

effect of, 247

principle of, 228, 231
types of,

Beard deputy, 257
Hughes, Evan-Thomas, 237
Wolf, 276

Emission of gases, 117. (See Trans-
piration, etc.)
ebb and flow, 208
old or abandoned workings, 117,

120, 205
spasmodic, 208

sudden e., 121. (See Outbursts)
English Mueseler lamp, 259
chimney, broad and short, 259,
260
English yard, See Y. (standard)
Entering a mine after explosion,

179
. call for volunteers, 180
examination of ventilation, 180
lamps, tools and materials, 180
organization of party, 181

selection of men, 181
division of work, 181

precautions,

avoid excitement, 179
carry a caged mouse, 144, 182
enter with and follow air, 181
observe breathing, pulse, etc., 182
watch lamps, 181

restoring ventilation, 181
necessary repairs, 181
Eternal lamps, 216
Ethane, 3, 112

Ethene, See defiant gas.
Ethylene, See defiant gas.
Evan Thomas lamps, 237

E. T. No. 7, 243

Hughes E. T., 237
Evaporation, 53

at all temperatures, 53

heat absorbed by, 53

transfers heat and equalizes
temperature in mine, 53
Examining a mine for gas, 340
(See lesting for gas)

begin at intake end, 340
proceed with the air, 340
walking into gas, 340
work must be thorough, 341
Examination Questions,
specific gravity, 40
chemistry, 41
heat, 72
Expansion, 54

adiabatic e., air and gases, 39,

60. (See A.)
caused by heat, 54
coefficient of, same for all gases,

54
cooling effect prevents ignition,

160
diagram — air and gases, 56
law of (Gay Lussac-Charles),

54, 55.
mine air, at time of firing, 203
relation of volume to —
pressure, 58-9
temperature, 55-7

solids, different for different
solids, 54
Expansions in —

compressed air, 91

powder (black), 63
Experiments, 188

dust, 166

Austrian commission, 169-170

Broockmann, 173

Galloway, 137, 138, 344

Hall, 138, 166, 192, 344

Prussian firedamp commission,
169

Royal (English) accidents com-
mission, 169

Vital. 138

explosives,

Accidents in mines commission,

199
British war dept. (Abel-Noble),

INDEX

377

Experiments, continued
flame caps,

Beard, 326, 333
Galloway, 333

flames, — Stokes, 297

heat, — Favre and Silbermann,

65
ignition of —

coal dust,' by electric lamps, 156,
gas (Dixon), 149, 161
, by electric lamps, 160

illuminants,

Roval accidents commission, 298,
299; conclusions, 299-301

laboratory e., value of, 115, 136,

174, 336
lamps,

Ashworth, 225

Royal accidents commission, 260

respiration,

Haldane and Smith, 186
Westphalian, 184, 185

sparks, by compression of air,

172
wire gauze — Davy, 225
Explosion of powder, See Gun-
powder.
Explosions (Dust), 162

action less sudden, 163, 164
characteristics of, 162
factors that determine, 164
flame intermittent, 175
gas, absence of, 138, 168, 169,

170, 171
increases force of e., 138,

169, 171
increases sensitiveness of d.,

138, 170, 171
persistence of, 163, 164
temperature, high, 163
Explosions (Gas), 161
a simple g. e. rare, 162
calculation of,

pressure due to, 212
temperature, 67, 214

centers of violence more pro-
nounced, 162
develops force in 20 yds., 162
differs from d. e., how, 146, 162
intensified etc., by d., 170
propagation of,

by concussion, 176

— dust, 162, 175

— percussion, 172

Explosions (mine), 146

afterdamp, chief cause of death,

180, 187
calculations, See E. (Gas),
causes,

(See Blasting, etc.)

( Ignition, etc.)

blasting, 196, 198
mixed lights, 194, 195
vainous c, 141, 160

character of blast, 161, 175, 17»
classification of, See types of.
effect of moisture in air, 193
effect on circulation, 180, 198

dust-covered lamps,

176
escape of survivors,

avoid afterdamp, 180, 187

excitement, 179

refuge stations. (See Rescue, etc.>

essential factors of, 171, 175
entering a mine after e., See

E., etc.
initiation of an e., 160

(See Gases in mines, ignition of)
occurrence,

in cold seasons, 206

— groups, 208

— metal mines, 132

— wet mines, 193, 206

periods of danger, 209, 212

frequency, 208, 212

phenomena of, See P., etc.
pressure due to, calculations, 212

transmitted by air, 135, 172
precautions,

re accumulation of gas, 191

— blasting, 196-204

— discipline, vigilance, 142, 191i
195, 209

— mixed lights, 194

— spraying, See S.

prevention of, 191

effect of cool walls, 149

propagation of, 169, 175

chemical activities started, 197
ignition of isolated bodies of gas,

172, 176
instantaneous, 172

recoil of. See Phenomena, etc.
record of, See R., etc.
relation of,

atmospheric conditions, 204
blasting, 196

seismic disturbances, 212
volcanic activity, 208

378

INDEX

Explosions (mine), continued
small proportion reported, 190
study of, 175, 188
types of, 146

dust e, See E. (D.)

gas e, See E. (G.)

local e., 198

Explosive atmosphere. See A.

(mine).
Explosive conditions (mines)

(See Atmosphere, mine)

(See Mine air)

(See Mine conditions)

air in circulation, 175
atmospheric conditions, 204

barometer, fall of, 204

heat and pressure, 13G, 141, 150

moisture, 160, 193, 206

temperature, 160, 206

blasting, 196

blown-out shot, 197

firing against air-current, 198

in gas, 201

in rotation, 202

in rapid succession, 198

flame of powder, 199
windy shot, 197

burning bad oil, 174
■decreasing circulation, 202-3
detecting e. c, See Testing for

gas, etc.
develop quickly, 136, 141, 176,

203 344
-effect of dust, 105, 138, 141, 196-
7. (See Coal d.)
least per cent, e., 137, 344
effect of extinctive gas, 171

flame, intensity of, 148

gob fires, 155

heat, pressure, 136,

141, 197
■effect of pressure, 150, 176

windy shot, 137

experiments to show e. c, 149,

161, 317
indicated by flame cap, 336
knowledge of, 134, 190, 196
reduced by watering, 192

need of, 212
relation to percentage of gas,

317, 336
thin seams, 149, 160-1
Explosive force or effect, 135, 153
Explosive mine gases, See G. (m. )
Explosive range (E. limits), See
Gases (mine),

Explosives, See Powders,
basis of comparison, 153
detonating e., 200

ammonium nitrate base, 200
guncotton. See G.
nitroglycerin. See N.
picric acid compounds, 200
pure firedamp not ignited by, 201

flameless e., 199

condensed carbon dioxide, 200
nitrated powders, 199
principle of, 199
water cartridge, 199

safe e. for gaseous mine, 199
Sprengle e., 199
temperatures of explosion, 200
theory of (Abel), 152-3
volume of gas produced, 153-4
Extinction of flame,
air necessary to f., 175
appearance of dying f. , 289
causes of e. (lamps), 147, 288-9
firedamp f., 140-1, 176
gas-fed f., 139, 140

explosion, f. of, 141

and dust explosion, 175

lamp f., See Safety 1., action,

etc.
percent, carbon dioxide, 110, 140

nitrogen required, 140

testing for gas, 230, 264, 329.

330, 334
wick relights from gas f., 223,

325
theory of, 289
wick-fed f., 140
wire gauze, by, 224
Extinctive atmospheres (arti-
ficial),
artificial vs residual (table), 140
produced by adding,

carbon dioxide, 139, 140, 144
methane, 144
nitrogen, 139, 140, 144

Fahrenheit hydrometer, 20

scale, 42

Fan drift, water deposited in, 92,

207
Fan, slowing down before firing,
202-4
accident due to, 203
argument in support of, 203

INDEX

379

Fatal atmosphefe, See A. (mine)
Faults,

cause change in gaseous con-
dition, 118
gas follows f., 118.
precaution needed, approach-
ing, 118
Feeder gas, 101

compared with occluded g., 102,

119
composition of (table), 102, 103

variable, 101-2, 103

effect of transpiration, 102, 119
fresh f. g. always sharp, 104
Feeders (gas), 120

carbon dioxide in roof, 122, 127
marsh gas in floor, 122, 127
effect on safety lamp, 223, 334
extinguishing f. burning in gob>

157
high pressure resists ignition,
160
Fiery mines, 134, See Gaseous m.
Fire boss Daw (lamp), 235
Firedamp, 100, 126. (See Meth-
ane)
composition,

percentage of gas, 103
137

proportions of gas and air, 103,

dilution with carbon dioxide, 140

methane, 140

nitrogen, 140

explosion of,

calculation of pressure, 58, 213
temperature, 67-8

explosive character, 100-1

effect of carbon dioxide, 104-5, 140
effect of carbon monoxide, 104,

137, 141
effect of dust. See C. d.

nitrogen, 105, 140

olefiant gas, 104, 137

explosive effect, 153
explosive limits (range), 101,
103, 137

effect of intensity of flame, 148
widened by carbon monoxide, 104

extinction of flame of , See E.,
etc.

Firedamp, continued

ignition of, (See Gases in

mines)
detonating explosives, 201
effect of dust. See Coal d.

extinctive gases, 171

inflammable gases, 158

hydrogen sulphide, 124,

158, 201
effect of olefiant gas, 104, 137,

158,201,225
isolated bodies of, 172, 175-6
temperature of 148, 202. (See M.)

— . — lowered, 158

time reqxiired, 148, 158

maximum explosive point, 101,
103

properties of, 101
Fireman's lamp, 236
Fires, Gob, 155

causes, 155

moisture assists, 155

odor of, 156

treatment of, 156
Fires, (mine), See M. f.
Fire tryer's lamp, 236
Fish oils, 294
Flame, 288. (See Gases-mine.)

accompanies ignition of gas, 147

air necessary to f., 175

appearance of, 289

blasting, f. of, 105, 197, 198

effect of volume and intensity
of f., See G. in m.

effect of gas on f., 134, 331

explosion (mine), f. of, 161, 175,
179

extinction of, See E., etc.

kinds of, 138

nature of, 288

persistence, tenacity of, 139, 288

temperature of, 69, 151

(estimated),

alcohol f., 152
candle f., 152
carbon monoxide, 151
hydrogen f., 151
methane, 151
oxyhydrogen, 152

temperature (theoretical),

carbon monoxide, 69, 151
hydrogen f., 151
methane, 69, 151

temperature, variable, 151
theory of, 288
I volume of, calculated, 69, 152

380

' INDEX

Flame (alcohol),

compared with hydrogen f., 272,

336
extinction of, 264, 272
height of f. caps, 335
in lamps, 269

Ashworth, 269
Chesneau, 2tio
Pieler, 262
Stokes, 267

sensitive to gas (high caps), 262,
266

temperature of, 152
Flame (candle), 287

compared with lamp f,, 139

gas-fed f., 288

extinction of, 140, 288

temperature (estimated) of, 152

theory of, 288

used for testing for gas, 215, 331
Flame (gas-fed), 287

compared with candle f., 288

wick-fed f . 288

extinction of, 140, 288

theory of, 288
Flame (hydrogen),

advantage of, 336

compared wuth alcohol f., 272,
336

compared with mineral oil f . , 336

extinction of, 140, 272, 336

height of f. caps, 335, 338

in oil lamp-Clowes, 270

temperature — calculated, esti-
mated, 151
Flame (illuminating),

classification, 287

luminosity depends on, 287, 289
Flame (lamp),

adjustment of for testing for gas,

Beard-Mackie lamps, 274, 324

Chesneau 1., 266

Clowes 1., 338

maximum cap to obtain, 334

Pieler 1., 263

reduced f., 330, 338, 341

alcohol, See F. (a.)

compared with candles, 139,

140, 297
effect of bonnet, See B.
carbon dioxide, 109,

110, 127

flashdamp, 127

gas in the air, 267, 332

Flame (lamp), continued
effect of illuminant, 332

(See Volatile oils)

experiments, See E.
extinction of, See Safety 1. (a.,

etc.)
height of f.,

danger of high f. in gas and dust,

345
effect of circulation, 224

illuminant, 299, 332

maintaining constant, 299, 300
normal f. in testing, 258, 329, 330,

338 343
reduced f. in testing, 330, 334,

338, 341
standard f. in testing, See S. f.
working f., 345

special f., 262
standard f.. SeeS. f.

Flame (oil-fed), 287

compared wdth candles, 288
extinction of, 140, 288
height of f. cap, 335, 338
theory of, 288

Flame (wick-fed),

compared with gas-fed f., 288
extinction, 140, 288
theory of, 288

I'h me cap. See Height of f. c.
difficult to observe, 104, 229,
334
smallest c. discernible, 342
effect of carbon monoxide, 104

dioxide, 127

dust, 344

flashdamp, 127

gas in air, 267, 332

illuminant, 332, 335

(See Volatile oils)

lamp, 335

■ — olefiant gas, 104

sharp gas, 104

formation of f. c, 104, 331
theory of, 331

visibility of c, 134, 229, 331
Flameless powders. See P.
Flame test, See Testing for gas (in

mines)
Flaming of safety lamp, See S. 1.

(a., etc.)
Flashdamp, 126, 129

composition, theoretical, 127

calculated, 12P

conditions favoring production,
127

INDEX

381

Flashdamp, ccmtinucd

explosive condition, calculated,

128
heavy f., light f., 129
Flashing of safety lamps', See S. 1.

(use of.)
Flashing point of oils. 296
determined how, 296
safe f. p. of mineral oils, 296
vegetable and animal oils safe,
296
Flooding mine to extinguish fire,

157
Fluid state of matter, 5
air is a f., 79
character of f . , 5
Foot-pounds, value in B. T. U., 48
Forces,

attraction, of, 9, 10

adhesion, 9
cohesion, 9
gravitation, 9
magnetism, 9
capillary, 12
chemical, 9
affinity, 9
elastic, 12

pressure (tension) of gas, 12
electrical, 10
inherent in matter, 9
magnetism, 10
repulsion, 10
French firedamp commission, 168,

265
French heat units, 47
calorie, value of, 47
pound-calorie, value of, 47
French meter. See M.
French, English, and U. S. stand-
ards compared, 354-6
Fuels,

comparison of, 70

heating value — calorific power,

69
heating value (table), 65
Fuses, use of in blasting, 201

Oallon (Standard).

English, 354, 356

United States, 356
Garforth's device, collecting gas,
313

Gas blower's, See B., etc.
Gaseous condition (mines), 134-6

change in,
gradual, 344
sudden, 117-8, 334. (See Explosive

c.)
dangerous, 203, 347-8

work in dark, 348
determines character of mine,

134 5
effect of barometer, fall of, 204,

329
effect of blown-out shot, 137

earth breathings, 208

explosion of keg of

powder, 137
effect of faults, 1 18, 204

open door, 329

— roof falls, 205, 329

squeeze, 344

gauging or estimating, 336
(See Testing, etc.)

variable, 118, 204, 208, 347
Gaseous mine, 135

danger of volatile oils in, 299
refuge stations in fiery and

dusty rh., 187
safe explosive for use in, 199
testing of lamps used, 349

Gases, Chemistry and Physics of, 4
(See G. — mine.)

absorption of heat by, 150, 289

diffusion of g, See D.

emission (transpiration), See E.

explosion of, calculation of, See

■ E., (g.)

gravity of g., 114

ignition of g., 147

accompanied by flame, 147
depends on, 148
effect of pressure, 150, 172
quicker from below, 148

by intense flame, 148

relation to absorptive power, 150
requirements — oxygen, heat,

moisture, time, 148
temperature of, 147

properties of g. — compressi-
bility, 11; density, 11; elastic
force, 12; expansion, 54; pressure
(tension), 12; viscosity, 12;
weight, 14, 114

mixture of gases and vapors, 93

laws of, 93
specific gravity of, 16
determination of, 19

382

INDEX

Gases^ Chemistry and Physics of,
continued

specific heat of, 49

constant pressure; c. volume, 50
effect of temperature, 50
equal volumes; e. weights, 51
ratio, c. pressure to c. volume, 51

temperature of ignition, 147

transpiration of, See T.
Gases (mine) classified,

diluent,

methane, 143
nitrogen, 113, 143

explosive,

carbon monoxide, 108

hydrogen sulphide. 111

methane, 100

[See G. (m.), explo. limits]
extinctive,

carbon dioxide, 140

methane, 140

nitrogen, 140

reduces explosive force, 171

renders dust inexplosive, 171

retards ignition of dust, 171
incombustible,

carbon dioxide, 109

nitrogen, 113

extinctive*of flame, 289

inflammable, 146

assist ignition of dust, 171

form explosive mixtures with air,

. 146

increases force of explo., 171

limits or range (methane), 103

irrespirable, See Atmosphere

(mine),
poisonous,

carbon dioxide, 110, 143

monoxide, 106, 108, 143

hydrogen sulphide, 111. 143
effect of depletion of oxygen, 113,

142
symptoms of poisoning, 108, 111,

182, 186
treatment of, 109, 110, 111, 182-3

"sharp ^' g., 104, 223, 250, 322,
325, 346
Gases (mine), (See G., etc:)

(See Carbon dioxide)

( monoxide)

( hydrogen sulphide)

( methane)

( olefiant gas)

absorptive power (table), 150

common m. g., The, 99

composition of,

evolved from coal, (table), 102
feeder, blower g. (table), 103

density (table), 3

diffusion (table), 124. (See D.)

ebb and flow, in strata, 208

Gases (mine), continued

emission of, See transpiration of.

explosive range (limits), 103,

137

determined by experiment, 136

effect of intensity of flame, 148

other g., 104, 316

pressure, 136, 316

temperature, 136, 316

extinctive effect of, 140

fatal effect of, 144

feeder g., See F.

heat energy of (table), 152

of combustion, 65

molecvilar weight (table), 3

occluded g.,

compared with feeder g., 102, 119

occlusion of. (See O.)

occurrence of,

as mixtures, 101, 102, 136
in abandoned workings, 117, 120,
191

— coal, 100. 102. 116. (See C.)

— pockets, 120, 346

— roof, 121, 204
on falls, 182, 204

pressure of occluded g., See O.
relation to m. explosions, 136
specific gravity of (tables), 3, 49,

124
specific heat (table), 49 .
symbol, chemical, 3, 49
temperature of ignition (table),

149
transpiration of, 117. (See T.)

changes character of g., 119-120

(See Feeder g.,,

effect of barometer, 205

roof falls, 117

greater in new works, 117
variable, 117

Gases in mines, (See G.-m.)
accumulation of, (See A.)
causes roof falls, 204
firing the g., 195, 215
isolated bodies of g., 131
removal of, 116
afterdamp, 181

behavior of, 114

detection of, (See Testing for g. )

presence made known, 135
effect on animals, 143

firedamp, 104, 158.

(See F.)
effect on flame, 135, 138, 141,

331
effect on persons, 143

INDEX

383

Gases in Mines, continued
ignition of, 147

causes — blown-out shot, 158, 197;
copper vs carbon brushes, 159;
electric wires Or motors, 158
flashing of lamps, 176, 276
glowing wood embers, 159
incandescent lamps, 159; in-
candescent particles (blasting),
201; naked lamps, 158; pyrites,
sulphur balls, 159; rapid com-
pression of air, 172 ; relighting
safety lamp in m., See S. 1.
(use of); sparks fromfsteel, 158-9
dilution of g. assists i., 131

prevents i., 100, 125

effect of coal dust. See C. d.

high velocitylof blower, 160

temperature of mine air,

159,175
effect of volume and intensity of

flame, 153, 160, 164, 171, 197
isolated bodies of gas, 172, 175-6
time required, 147, 148, 158

measurement of g., 345

in airways, 347

— rooms, 347

reported as inches of g., 346

mix, intermingle, 126

precautions in g.,

against being overcome, 144, 179,

182
against ignition of g., 181, 201
walking into gas, 340

pressure of occluded g, (See 0.)

assists the mining of coal, 121
causes roof falls, 121, 205
audible sounds, See Bumps.

stratification of, 115, 334
travels through roof joints, 123

Gas-fed flames, See F. (g.-f.)

Gas feeders. See F. (g.)

Gas finder's lamp, 236

Gasoline, 295

Gas pockets, 120, 346

Gauzes, Lamp, 339. (See Wire g.)
cap, g. (smoke g.), 222, 240, 241,
244, 339
conical c, 239

chimney, g., See C.
cleaning. 247, 339, 350
dirty and oily, 225, 276, 299
iron vs copper, 220
mesh,

fine, 1,264 openings per sq. in.,

266
standard 784 openings per sq. in.,

225, 266

Gauzes, Lamp, continued

multiple, 246, 247, 274

double, 228, 232, 246, 298
protection afforded, 247
triple, 232, 246

principle of, 224
size and shape of,

conical, 249, 250, 252, 253, 339

cylindrical, 225

high, 263

horizontal g. diaphragm, 261

large, 238, 264

small, 253

Gay Lussac's law of gases, 54, 55

diagram illustrating, 56
Gelignite, 200
"Geordie" lamp (Stephenson), 239-

cap, copper, 240

dimensions of gauze, 240

favorite testing 1., 240

glass chimney within gauze, 240

oil burned, 240

original L, 239

tested in blower, 219, 239
theory of, 219, 240

Glasses, Lamp, 339

black strip on g., 274

cleaning, 339

conical, 240, 250, 252

cool g. transmits light better,
245

cracked by heat, 250

double, 245
Gob fires, See F.
Grain, The — basis of comparison,

359
Gravitation, 9
Gravity, Force of, 14

acts on each unit of mass, 14

formula, any latitude and ele-
vation, 76

eff"ect on barometric pressure, 90

value at different latitudes, 76

New York, Paris, 76,

varies, 14

with latitude and elevation, 76
Gravity of gases, 114
Gravity, Specific, See S. g.
Gray inlet tubes, 248, 252, 254

single inlet t., 256
Gray lamp, 248

bonnet, openings in, 249

distinctive features, 248

384

INDEX

<3ray lamp, continued
effect of tilting 1., 250
extinction of, in gas, 250
illuminating power, 250, 306
inlet tubes, 248, 252, 254
oil burned, 250

resistance to current velocity,
250

■Guessing per cent, of gas, See
Testing for g.

Guncotton, 200

heat energy per pound, 152

of combustion, 64

explosion of,

chemical reaction, 64
products of, 64
temperature of, 65, 200

Gunpowder, (See Black blasting
powder)

composition of, 64

heat energy per pound, 152

expansions at sea level, 63

explosion of,

chemical reaction, 64
temperature of, 63, 154, 200
vplume gaseous products, 63, 154
solid residue, 63, 64

Heart weak, danger in gas, 181
Heat, 13, 42

absorbed by gases, 150, 289

in chemical change,

145
absorbed by metal, 147, 224
capacity of bodies for, 42,45-6,

48
due to chemical change, 39, 45,

154
due to change of volume, 39, 214

compression, 39, 59, 172

effect of h. to produce —

change in matter, 6, 46
expansion, 54, 58
explosive condition. See E. c.
sensation of touch, 13, 45

energy in blasting, 196, 198
of combustibles, 152,

196
energy of explosives, 153, 196,

198

Heat, continued

how discerned, 13, 45

estimated, 48

imparted, 13, 46

hypothesis of, 42, 45 46
kinds of,

chemical h. See C. h.

h. of combustion, See C.

- — compression, See C.

- — fusion, 52
vaporization, 52

- in steam above 32° F., 52
formula (Regnault), 52
latent h., 51, See L. h.
sensible h., 51

measurement of, 14, 47

mechanical equivalent, 48
quantity of, 14, 45
units of. See U. of h.

nature of,

condition of matter, 13, 14, 45
form of motion, 13, 42, 45

sources of, 39, 45, 172
temperature, relation to, 42
transmission of, 46

by conduction, 46

— contact, 13-4

— convection, 46

— radiation, 46

Heat capacity (of bodies), 48 .
Heating value (Calorific power)'
69

combustibles (table), 65

formula (Dulong), 70

fuels, comparison of, 70
Heat units. See U. of h.
Heavy flashdamp, 129
Heavy hydrocarbon gases, 111,

112. (See H. gases.)
Heavy lubricating oils, 295
Height of flame cap, (See F. c.)

depends on,

activity of combustion, 332
circulation, free, in lamp, 332, 338
h. of original f., 333
inflammability of gas, 127, 331

oil, 331

proportion of gas and air, 331

effect of —

bonnet (Davy), 327, 332
carbon monoxide, 104
coal dust, 344

cotton in oil vessel, 264, 266
heating of lamp, 267
illuminant, 332, 335
lamp, form of, 332, 335
volatile oils. See V. o.

INDEX

385

Height of flame cap, continued
flames, different, 335
alcohol f.. See F. (a.)
benzoline f., 335
colza f., 335
hydrogen f.. See F. (h.)
naphtha-benzine f., 335
sperm or lard-oil f., 335, 338

formulas, 333
Galloway's law, 327, 333

confirmed, 327

indicates —

degree of danger, 336
explosive condition, 336
percentage of gas, 308
presence of dust, 344

maximum h, of c, 334
measurement of,

by guessing, 229, 334, 341

— scale, 264, 266, 272, 337

interpretation of, 336

need of accuracy, 228, 230, 334,
336

per cent, of gas, relation to, 228,

327, 332
variations in observed h. of c,
336
History of coal dust, 164
History of safety lamps, See S. 1.

(h.)
Hood of safety lamp, See Bon-
nets.
Horsepower, heat units (B. T. U.)

per, 48
Hospital mine, 186
House of Parliament, (Eng.)

burned, 354
Humidity of air. See A.
Hydrated peroxide of barium, 185
Hydrated lime and caustic soda,

185
Hydrocarbon gases, 111, 112
distilled from petroleum, 295
mixed with other g., 101
occluded in strata, 116
transpire more quickly, 102, 119
vaporous h. g., 295
Hydrogen, 114

absorptive power, 150
diffusion, rate of, 124
explosive limits, 137

widest range, 137
flame, See F. (h.)
in afterdamp, 114, 129, 131
chemical reaction, 130
how produced, 114
composition of mixture producing,
130

Hydrogen, continued

Marsh gas called h. by miners.

114
properties, 114
specific gravity, 3, 49, 124

heat, 49

standard unit weight of, 363
temperature of ignition, 149
transpiration, rate of, 119
unit of atomic wt. and vol., 15

Hydrogen cylinder (Clowes lamp).
See C. h. 1.

Hydrogen dioxide, 109
Hydrogen flame, See F. (h.)
Hydrogen lamp (Clowes), See

C. h. 1.
Hydrogen peroxide, 109
Hydrogen sulphide, 110

density, 3

detection of (odor), 110, 111

diffusion, rate of, 124

effect on life. 111

firedamp, 124, 158,

201

explosive mixture with air. 111

formation in mines, 110-111

ignition, temperature of, 149

in sulphur mines, 132

— volcanic regions. 111
poisonous action of, 111
properties of , 110-111
specific gravity, 3, 49, 124

heat, 49

temperature of ignition, 149
transpiration, rate of, 119

effect of, 124
treatment of persons overcome
by, 111
Hydrometer,
Baume, 21

Nicholson (Fahrenheit), 20
Hydrostatic balance, 17
Hygrodeik, 98

Hygrometer, Leslie's or Mason's,
96-7
use of — formula, 97-8
Hygrometric condition of air, See
A.

386

INDEX

Igniter -in safety lamp, 274, 276,
278
danger of, 276, 277, 299
in Vv olf lamp, 274-7, 278
— Amer. S. L. Co. L, 286
Ignition, temperature of See T.
Ignition of —

coal, 154, 155, 156
coal dust. See C. d.
combustible material 156, 175
isolated bodies of gas, 172, 176
mine gases, See G. in m.
Illuminating flames, See F. (i.)
Illuminating oils, See lUumin-

ants, etc.
Illuminating power,
candles, 290, 297
causes of differences, 289, 297
depends on, 287
determination of, 290-2
effect of —
bonnet, 298

chimney (Mueseler), 260
circulation. 245, 260, 297, 305
gauze (Davy), 305

double (Marsaut), 298

mixing petroleum, 298
platinum wires, incandescent,

312
safety lamps, 305-7
Ashworth, 251, 306

Hepplewhite-Gray,

256, 306
Beard deputy, 258, 306
Clanny, 243, 306
Davy, 235, 306, 307
Evan Thomas, No. 7, 244, 306
Gray, 250, 306
Marsaut, 248, 306
Mueseler, 260, 306
Stephenson, 240, 306
Thompson, 293
Wolf 280, 306
standard flame, light unit, 290,

297
variation of, 289, 306
lUuminants for safety lamps, 292
(See I. -special.)
(See Oils.)

adulteration. See Petroleum,

Mixture of.
classification of oils, 293

animal o, See A. o.

mineral o, See M. o.

vegetable o, See V. o.

danger of volatile o., 292. (See
V. o.)

lUuminants for safety lamps, con-
tinued

effect on flame cap, See F. c.

light, 297

experiments, conclusions, See E.

flashing point determines dan-
ger, See F. etc.

kinds of,

gas (acetylene), 292-3
oils, See O.
solid paraffin. See P.
special i, See I. (s.)
volatile o, See V. o.

quality sold and used, 1 74, 301

best, need of, 300, 301

testing,

flash (open) test, 296-7

purity by incrust of wick, 294

smoke test, 301-3
use of lubricating o., 301

eflfect in mine, 174, 301
lUuminants (special), 262
r (See Volatile oils.)
acetylene gas burned in,

Thompson 1., 292-3
alcohol burned in —

Ashworth, 230, 251, 269

Chesneau, 262, 265, 269

Pieler, 230, 262

Stokes, 230, 262, 267

benzine, 284, 286, 295, 296
benzoline, 257, 295
coal oil. See Petroleum,
colza. See C.
colzaline (gasoline),

in protector lamps, 295
gasoline, 295
hydrogen, for testing only,

Clowes h. lamp, 230, 270, 337

h. vs alcohol, 272
naphtha (benzine), 295

Wolf lamp, 230, 262, 277
paraffin, 292, 295, 299

Ashworth lamp, 251
petroleum, See P.
spirit (methylated), 251, 257 '
Incandescent lamps,

difference, high and low voltage.

159-160
ignition of coal dust, 156

experiments, 156
ignition of gas, 159-160, 196
Incandescent dust,
in blasting, 201
— mine explosion, 131, 144, 174

red hot sparks, 164, 176

Incandescent wires. See Indica-
tors.

INDEX

387

Incombustible dust, See D.
Incombustible gases, See G.

(mine)
Indicators, Gas, 308

Aitken, 309

Ansell, 309

Beard-Mackie sight i., SeeB. M.,
etc.

Coquillion, 308

Forbes, 313

Libin, 309

Liveing, 310

Maurice, 308

Monnier, 308

Smith, 309

sundry appliances, 314
Indicators, Gas, principle of,

absorption of g. by platinum
black,
increase of temperature, 309

burning out gas,

decrease of air volume, 308
pressure, 309

compression of air,

ignition of g. causes flash, 310
diffusion of g. into air space,

increase of pressure, 309
expansion of metal strip,

rings a bell in lamp, 314

incandescent platinum wires,
i. by electric current, luminosity,

311
i, by gas, ladder scale, 324

sound waves in air and gas,
pitch of tuning fork, 313
Inertia, 13
Inflammable —

coal, See C.

dust; See Coal d.

gases (mine). See G. (m.)

materials in coal measures, 146,
147

range of methane, 103
Inlet tubes (Gray), See G. i. t.
International Bureau of Stand-
ards, 353

established, 358

location, 359
Ionization, 5
Ions, 6

Iowa, mine inspection reports, 203
Iron in lamps, 220
Iron gauzes, 220

Irrespirable atmosphere, See A
(mine)

Kerosene— coal oil, 295, 296, 300,
340

(See Petroleum)
Kilogram, unit of mass, 358
Klondyke mine disaster, 344
Knockings, in mine, 117

Lamp brushes, 339
Lamp house, The, 349
arrangements, 349-350
construction, 350, 352
operation of, 349-352
plan, 350
Lamp hood, 263. (See Bonnets. )
Lamps — (See Safety 1.)

burn in fatal atmosphere, (See

A. (m)
eternal 1., 216
extinction of,

air still respirable, 110, 144
causes of, 147, 288-9

incandescent 1., See I. 1.

mixed lights, 194

open lights, 195
Lamp standards. See S.
Lard oil, 294

illuminating power greater,
294-5

incrusts wick less, 294
Latent heat, 51

of ice, 52

— steam, 52
Law (mine),

disregarded, 195

Belgium, 236, 243, 260

England, 236, 243, 330

France, 236, 243, 330

Pennsylvania, 236, 243
Lead-plug lock, 281

simplest 1., 282

making the rivets, 282-3

rivet mold, 282
Legislation needed, 188, 191, 301
Leslie's or Mason's hygrometer,

96. (See H., etc.)
Light carbureted hydrogen, See

Methane.
Light flashdamp, 129

388

INDEX

Light oils, 295. (See Volatile o.)
Lights — (See Lamps),
mixed 1., 194
open 1., 195
Liquid — a fluid, 5
properties of,

least compressible, 11
elastic, 12

specific gravity determined, 18,
19
Liter, unit of volume, 358
Liveing indicator (gas), 310
construction of, 31 1
principle of, 310,311
sources of error, 312-3
use of. 311-2
Locks for safety lamps, 280
kinds, 281

air 1., automatic, 245, 286
lead-plug 1., 233, 281
magnet 1., 284, 285
protector 1., 283
screw-bolt, 281

need of, 233
purpose of, 280
requirements, 281
to fasten bonnet, 245
Lyddite, 200

Machines (mining) cause fine dust,
192

Magnesia dust, effect, 173

Magnetism, 9, 10

Magnet lock, 284, 285
compared with air 1., 287

Mariotte's law of gases, 59

Marsaut lamp, 246

compared with Clanny, 246

Mueseler, 262

distinctive feature, 246
illuminating power, 248, 306
multiple gauzes, See G.
oil burned, 248
protection afforded, 247
resistance to current velocity,

248
unbonnet^d M., use of, 246

Marsh gas, See Methane.

Marsh gas series, 112

Mason's hygrometer, 96. (See H.)

Mass, 5, 11

Matter, 5

change in form produced, 5-6
condition (state) of, 5, 10, 13, 42
constitution of, 10
divisions of, 6

chemical, 6, 10

electrical, 6, 10

elementary, 7

energy (kinetic) of, 122

motion of, 10, 13, 42, 121-2

properties of, 10

theory of, 121-2

Dalton's t. of m., 5, 10, 14

Mauchline (Bull's eye) lamp, 245
Mechanical equivalent of heat, 48
Mechanical mixture, 7

air a m. m., 74
Melenite, 200
Melting point, 6

of ice, 43
Mercurial barometer, See B.
Mercurial vapors in mines, 133
Mercury,

in barometer, 80

— thermometer, 44

weight of, 81, 363
Mercury column explained, 80-1
Meridian quadrant of earth, 353

natural standard, metric system,
353
Meter,

base of metric system, 358

comparison, English and U. S.
values, 356

derivation of, 353

value— English 355-6

United States, 356

Methane (marsh gas), 90
(See Firedamp)
(See Gases in Mines)

absorptive power, 150
combustion of (explosion), 28,

129-130
change of volume-none, 35
chemical reaction, complete c, 29,

67, 212
chemical reaction, incomplete c,

130
energy developed, 152, 196
flame temperature, See F.
heat of c, 65

temperature, initial, 67-8, 154
volume of g. produced, 154

density, 3

detection of, See Testing for g.

INDEX

389

Methane, continued
diffusion of, 100, 125

^ rate of. 124

effect on flame, 100-. (SeeP\)

— human system, 100,

143

least per cent, fatal, 144

expansions above zero, F., 68
explosion of, See Firedamp,
explosive limits, See F.
formation of, 100
ignition, See F.
inflammable range, 103
occurrence,

feeders in floor, 122, 127
in coal seams, 99-100
— metal mines, 132
properties of, 99-100
specific gravity, 3, 49, 124

heat, 49

temperature of ignition, 148,149
transpiration of, See G. (mine)
rate of, 119
Metric system, 357

adopted by Governments, 358
description, 58
general use of, 356
history of, 357

legalized in United States, 357
no natural standard, 358
universal basis of comparison,
356
Mice in mines,

indicates absence of gas, 107
used as test for gas, 107, 143,
182
Mine air, 132. (See Atmosphere,
m.)
composition of, 168
analyses, 133, 168
carbon dioxide, per cent., 132, 168
oxygen, 133, 168
disturbance of. See M. con-
ditions,
differs !rom atmospheric a., 132
expansion in blasting, 203
explosive conditions, See E, c.

gaseous , See G. c.

moisture in, (See Air)

amount small in winter, 206
assists gob fires, 155
deposited in airways, 92, 207
downpour in fan drifts, 92, 207-8
effect on explosive condition, 206
importance, in dust explosion, 164
relation tb explosion, 175, 193
weight of, in air-current, 207
spraying, effect of, 192, 193

Mine air, continued

temperature desirable, 202

, effect on ignitioD

of gas, 159, 175

normal at firing

time, 202
Mine atmosphere. See A. (m.)
Mine conditions,

air disturbance, due to —

air-current, 289
closing of m. door, 141
explosion of gas, 131, 174, 176, 272

keg of powder, 137

shot, 141, 198

roof falls, 141, 195

chemical action in m., 154, 197

explosive c. See E. c.

gas,

accumulation of, See A., etc.
combustion of, (temp.), 151, 196
diffusion of 123. (See D.)
explosive effect, great, 153
generation of, 123
margin of safety slight, 176, 344
fisk assumed, 134, 195, 196, 201;

299
precautions necessary, 135, 191,

J 95. 348
pressure of g. in strata varies, 208

effect of cold intake, 207
physical c,

cul de sac, 175, 196

earth breathings, 208

faults, 118, 204, 208

feeders, 208

roof falls due to gas, 121, 205

settlement causes heat, 155

, poundings,

bumps, 117
standing areas, 191, 204
workings, size of, 161, 164, 175,

197
workings, temperature, 175, 198,
207
Mine explosions, See E. (m.)
Mine fires,

flooding m. to extinguish, 157
Littleburn Colliery, 156
Mine gases, See G. (m.)
Mine hospital, 186
Mineral oils, 295
kinds of,

benzine. See B.
benzoline, 257, 295, 335
coal oil. See C. o.
colzaline, 295
gasoline. 295
kerosene. See K.
naphtha. See N.
petrolMim, See P.
rock oiTr 295. (See Petroleum.)
vft animal and vegetable o., 298
require more oxygen, 298
restricted circulation effect of 29S

390

INDEX

Miners,

disregard of danger, 142, 194-5

ignorance of, 194, 196

practices of See P., etc.

protection of health of, 301
Mines,

classification as to gas. 134

fiery, 135
gaseous, 135
non-gaseous, 134

kinds other than coal,

copper (Lake Superior), 132

iron, 132

lead, 133

metal, 132

quicksilver, 133

salt, 133

sulphur, 133

mentioned, See Record of m.
explosions.

Belgian m.. 215

Herring Mill colliery, Eng., 217

Killingworth , 219,

239
Marvine colliery. Pa., 324
Silver Islet, L. Superior, 132
Shamrock mine, WestphaUa, 185
Whitehaven collieries, Eng., 217

thin seams, 149, 160-1, 212
Mixed lights, 194
Mixture of gases and air, 126, 146

properties of m., 126
Mixture of gases and vapors, laws,

93
Moisture in mine air, See M. a.
Molecular motion, 122
Molecular volume, 15
Molecular weight, 15

calculation of, 30

of mine gases (table), 3
Molecules, simple, compound, 7
Mount Pel^e, eruption of, 209
Mouse test for gas, 107, 143, 182
Mueseler lamp, 259

Belgian M.,

dimensions of, 260
legal 1. in Belgium, 260
superior to EngUsh M., 260

chief characteristics, 260

chimney, conical sheet-iron See
C.

compared with Davy or Clanny,
262

Marsaut, 262

conditions in 1,, 261-2

English and Belgian M. com-
pared, 259

Mueseler lamp, continued

extinguished easily by canting,

232, 262
horizontal gauze diaphragm,

261
illuminating power, 306
requires a uniform circulation,

261
resistance to current velocity,

260
resistance to explosion, 260
•types, Belgian, English, 259

Naphtha,

distilled from petroleum, 295
in rock formations, 147
— lamps, 276, 278
70-degree test, 278

Natural standards. See S.

Nicholson's hydrometer, 20

Nitrated powders, 199

Nitrogen, 113
absorptive power, 150
artificial atmosphere, 139, 140
density, 3

diffusion, rate of, 124
effect on firedamp, 105

flame, 113

respiration, 186

extinctive effect, 139, 140

per cent.-lamp flame, 140
— - — - -firedamp, 140

not poisonous, 113, 143

occurrence, 113

per cent, added to air, fatal, 144

properties, 113

proportion in atmosphere, 75

purpose , 74

specific gravity, 3, 49, 124

heat, 49

transpiration, rate of, 119
Nitroglycerin,

base of detonating explosives,'

200
explosion of,

chemical reaction, 64
products, gases only, 64
temperature of, 154, 200
volume of gases, 154

heat energy per pound, 152

INDEX

391

Nitrous oxide (laughing gas), 112

absorptive power, 150

density, 3

effect on combustion, 1 12-3

human system, 112-3

in afterdamp, 112, 129

lieat energy of, 113

properties of, 112-3

specific gravity, 3, 49

heat, 49

treatment of persons overcome
by, 113
Non-gaseous mines, 134

Occlusion of gases, 116

pressure of, 116, 120-1, 205
volume of g. from coal, 102, 116
Oil-fed flames. See F. (o. f.)
Oils, (See Illuminants, etc.)
animal o.. See A. o.
bad quality, 133, 174, 294, 301,
305
detection of, 301
chemical analysis, 301
compared with candles, 140, 297
crude o., 295

flashing point of, See F. p., etc.
lubricating o., 295
mineral o.. See M. o.
purifying, 294
rock o., 295
sources of, 293
testing, See Illuminants, etc.
vegetable o., See V. o.
volatile o. See V, o.
Oil tank for filling lamps, 278, 350
Oil vessels (lamps) special,
double v., 269
filled with cotton, 264, 266, 277,

286, 296
interchangeable, v., 251, 252
arranged to burn, (See Illumi-
nants. )
acetylene gas, 293
alcohol, 252. 257, 264
benzine, 284. 286
benzoline, 257
. hydrogen, 270-1

naphtha (benzine), 257, 277
paraffin, 252
spirits, 251, 257

Olefiant gas. 111

absorptive power, 150

density, 3

detection, 112

diffusion, rate of, 124

effect on firedamp, 104, 124,

137, 158, 201, 225
effect on flame, 104, 112

cap, 104

ignition of g., 158

explosive limits, 137
heat energy of, 152
occurrence. 111
properties, 112
specific gravity, 3, 49, 124

heat, 49

transpiration, rate of, 119

high, effect of, 119, 124
Olefines, 112
Open test for oils, 296
Outbursts of gas, 121
carbon dioxide, 121
France, 121
Morrisey, B. C, 147
to prevent, 121
warning of, 121
Oxidation, 62
forms of, 63
Oxygen, 114

absorption of by coal, 154

dust, 156, 173,

174
absorptive power of, 150
combustion, necessary to, 165,

175
compressed o. in rescue work,

185
depletion of in air,

dangerous to life. 106, 113, 133,
142

effect on flame, 140, 289

— respiration, 186

fatal results. 143

increases toxic effect. 113, 142
diffusion, rate of, 124
effect of excess of, 186
in atmosphere, (See Air)

per cent, by volume, 75

weight, 75

supports combustion, 74

— ; life, 74

in mine air, per cent., 133

properties, 114

specific gravity, 3, 49, 124

heat, 49

transpiration, rate of, 119

392

INDEX

Oxyhydrogen flame, temperature,
152

Ozone, formed in breathing ap-
paratus, 185

ParaflSn,

distilled from petroleum, 295

solid p. in lamps, 251, 292, 299

Parliament, House of, England,

burned, 354
Pendulum (seconds),
length at London, 354
natural standard of length, 354
Percentage composition,
by volume, 34
— weight, 32
Percentage of gas, (See Height
of flame cap)
causing lamp to flame, 264, 347
determining, See Testing for g.
increases, approaching feeder,

334
increases, approaching source,

347
indicates conditions in mine,

336. (See H., etc.)
in firedamp mixtures, 103
interpreting p., 336
measurement of,

by height of flame cap, 308. (See
H., etc.)

— incandescent wires, 258, 274,
312 325

— inciicators, 308. (See Testing
for g., i.)

— Shaw g. machine, 315, 319

relation to h. of f. c, 327, 332,
333

formulas, 327

safe p. for working, 343, 347

anthracite coal, 348
bituminous , 348

small p., detecting, See Testing
for g.
Percentage wires, B. M. indicator,

258, 324
Percussive theory (mine explo-
sions), 172
Periods of danger in mines, 209,

212
Periods of frequency mine ex-
plosions, 208, 209, 212

Peroxide of hydrogen, 109
Petroleum, 295

composition, distillation, origin,
source, 295

refined p., 295

tenacity of flame of, 301

use deplored in gaseous mines,
299
Petroleum, Mixtures of,

and colza, 298, 300

rape, 298

seal o., 300

sperm or lard o., 294, 300,

340, 349
effect of,

creates tendency to smoke, 294

fouls the air, 133

increases illuminating power, 294,

298, 300
increases rate of burning, 298, 300
lamp heats quicker, 300
maintains more uniform flame, 300
reduces incrustation, 300

flashing point required, 296,

300, 349
mix at mine, 300

oils equally consumed, 300
proportions of mixing, 294, 300,

301, 349

eff"ect of varying, 300
purpose of mixing, 294
Phenomena of mine explosions,

174
absence of alarm, 174

flame, 175

evidence of blast,

162, 172
centers of e., 162, 176, 178
cul de sac, 175, 196
dust,

clouds of, 176

coking of, See C, etc.

deposit, inches deep, 176

on timbers, See Coal d.

ignited, glows as furnace, 166, 196

incandescent d., 131, 144, 174

sea of d., 176

shower of sparks, 164, 176

flame of e., See F.

return f. hotter, 178, 179
— less violent, 179

instantaneous effect, 145, 172,

174
recoil of e., 179

return flame, 178, 179

theory of, 179

third flame rare, 179

rush of wind, 174-5

INDEX

393

Phosphorescent substances in

mine, 216
Photometer, 290

Bunsen's p., 291

graduation of scale, 292

principle of, 292
Photometry of safety lamps, 287
Physics of gases, 4
Picric-acid compounds, 200
Pieler lamp, 262

burns alcohol, 262

compared with Chesneau, See C.

dangerous in gas, 264

extinguished easily in gas, 264

flames above 2 per cent, of g.,
264

heats quickly in gas, 267

height of gauze, 263

oil vessel contains cotton, 264

resistance to current velocity,
264-5

scale to measure flame cap, 263,
264, 338

sensitive to gas, 263

small per cent, only, 264

time required to cool, 267

useless when hot, 267
Pipe lines for —

spraying the mine, 194

supplying air to refuge stations,
187
Platinum,

compared with spongy p., 325

heats in gas, 325

degree of heating, 325

induces chemical action, 325

Platinum black,

in Aitken indicator, 309
— Smith , 310

Platinum foil heated glows in gas,
325

Platinum wire,

electrical resistance varies, 313
incandesces above tip of flame,

326
used in indicators,

Aitken, 309
Beard-Mackie, 324
Coquillion, 308
Liveing, 312
Maurice, 308
Monnier, 308

Pocket Davy lamp, 235
Pockets of gas, 120, 346
Poisoning (gas), Symptoms of,

blood bright red after death,
109

delirious on reaching air, 108,
182

giddiness, 108

loss of consciousness, 108, 111,
182

loss of power to move, 108, 182

nausea, 186

palpitation of heart, 108

prostration, 111

rapid pulse, 182

respiration difficult, 186

talkative, 182

weakness in limbs, 108, 182
Poisonous mine gases, See G. (m.)
Porosity, 12

relation to compressibility, 11
Pound (avoir.), standard,

English, United States, 356
Pound-calorie, 47
Poundings (gas) in strata, 117, 121
Powders,

See Black blasting p.

Explosives.

• Gunpowder.

Practices, Dangerous,

(See P., Early)

re blasting,

lighting shot, heated wire, 202
locating shots, 198
slowing fan before firing, 202, 206
tamping combustible material,
202

re gas,

Hghting the gas, 195, 215
no visible cap, no danger, 343
slight margin of safety, 176

re lamps,

high flame, 345
mixed lights, 194-5
opening!., 281-2
playing with 1., 277, 282
relighting 1. in mine, See Safety

1., (use of)
use of lubricating oil in 1., 301
— petroleum (coal oil) in I.,

133, 301

re testing for gas,

guessing per cent, of g., 229, 334
turning lamp on side, 342

394

INDEX

Practices, Early (re gas), 215
accidents due to, 217, 239
"Eternal lamps," 216
firing the gas, 215
lamps, use of —

Clanny, 217

Scotch Davy, 238

Stephenson, 219, 239

prejudicial favor, 239
steel mill, Spedding's, 216
testing for gas, 215, 331
Pressure,

absolute p. (p. above vacuum),

58
adiabatic change of, 39-40, 60,

61, 214
atmospheric p., See A. p.
barometric p., See B. p.
change of p. due to c. of volume,

58
effect on —

absorptive power, 150

air or gas, 58, 124

boiling and melting points, 6

density, 6

explosive condition, See E.

ignition of gas, 150, 176

matter, 11

explosion of gas,

calculation of p, 58, 212
in hydrogen cylinder, 271, 272

— oxygen , 185

measured in atmospheres, 91,

185
occluded gas, p. of, 116, 120,

205
variation of, in earth, 208
relation to temperature, See

Absolute p.
relation to volume. See Abso-
lute p.
Pricker, safety lamp, 304
Protector lock for safety lamp, 283
Protector lamps, 296

extinguished by opening, 283-4
Prussian firedamp commission,

169
Purifying oil, 294
Pyrites, 154, 159

Questions, Examination,
chemistry, 41
explosion of powder, 73

Questions, Examination, continued
fuels, 72
heat, 72-3
specific gravity, 40
ventilation, 72-3
water evaporation, 72

Range, Explosive, of mine gases

See G. (m.)
Rape oil, 293

effect of adding petroleum, 298

(See P., Mixtures of)
experiments, results of, 299
purifying, 294
rate of burning, 298
summer r., 293
winter r., 293
Rate of diffusion (gases), 123-4
Rate of transpiration (gases), 118,

119
Rats and mice in mines, 107
Reaumur (thermometer) scale, 42
Recoil of mine explosion. See Phe-
nomena of m. e.
Record of mine explosions, 188,
209-211
Campagnac, France, 138
Cedar Mines, Iowa, 177
Courrieres, France, 183
Femie, B. C, 177
Haswell, England, 165, 177
Indian T., 190
Iowa, 203
Klondike, Rolling Mill mine, Pa.,

344
Penygraig, Wales, 182
Seaham, England, 166

Usworth, , 177

Wallsend, , 164

Refuge stations, 186

Regnault's formula for B. T. U.,

52
Relighting safety lamps in mine,
advantage of, 275-7, 299
danger of. See Igniter, etc.
Repulsion, 10

between liquids and solids, 13

INDEX

395

Rescue work in mines, 179. (See -
Entering a m.,etc.)
ambulance, stretchers, blankets,

etc., 183
apparatus (breathing), 183-6

general principle, 184
mouthpiece, cfetail of, 184, 185
oxygen cylinder, capacity, press-
ure, 185
principle of injector, 185
regeneration of expired air, see A.
Shamrock (Meyer), 184. 185
respiration, free, 186. (See Air.)
Vajen-Baden helmets, 184
vaseline, use of, 185

supplies on hand at mine, 183
mine hospitals, 186-7
refuge stations in mine, 186

approved s., 187

need of, in fiery and dusty m., 187

pipe line connection, 187

drill hole connection, 188

symptoms of effect of gas, 108
111, 182, 186

trained men in mme, 183

corps on surface, 183

treatment of those rescued, 109,
110, 111, 182-3
Reservoir of gas, 120
Residual atmosphere, 139, 140
Respirable atmosphere extinctive,
110, 144
safe to withdraw from, 110
(See A,, mine)

Respiration,

amount of air respired, 184-5
effect of carbon dioxide in air,'

186
effect of depletion of oxygen,
186
Rivet mold, 282
Roburite, 200

Rock oil, 295. (See Petroleum.)
Roof falls. See Mine conditions.
Royal coal-dust commission. See
C.

Safety lamps (action in gas).
explosion in 1., 223, 225, 260,
346

Safety lamps (action, etc.), con-
tinued
extinction of 1.,
by bonnet, 224

— canting 1., 244, 252, 262

— gas, 223, 250

— poor circulation, 223, 252
due to volatile oil, 230, 264
prevented in A-H-G 1., 255
testing for gas. See E. of flame.

failure of 1., 225

causes, 225, 226, 278
(See flashing of 1.)

flaming of 1., 222, 224, 235, 264,
334, 347
balloons of flame, 223
per cent, of g. causing f. 264, 347

flashing of 1., 176, 276

due to dusty 1., 176

volatile oil, 230, 276, 299

heating of 1. in g., 224, 228, 267
small 1. heat quickly, 236
time required to (5ool, 267
useless in testing, 267

relighting after extinction, 223,

325
sensitive to g., 222, 228
Safetv lamps (care of), 339, 348
checking 1., 349, 350, 352
cleaning 1., 247, 348, 350
examined, 348, 350, 352
filling 1., 277, 278-280, 340,

350-1
fire bosses' 1., 339
miners' l, 348
miners receiving 1., 351-2

returning 1., 349-350

ownership of 1., 348
preparing 1. for use, 339, 352
repairing 1., 349, 350
storing 1. in 1. house, 351-2
supervision, control, 348
testing the 1., 226, 233, 348-9
Safety lamps (classification), 227
1. for general use, 230

types of, See S. 1. (g. w.) etc.

testing for gas, 227. (See

T. 1.)

types of. See T. 1.
requirements (testing 1.),

free circulation, 227
gauze chimney, protection of, 228
measurement of flame cap, 228
requirements (workmg 1.),
maximum illumination, 230
security, 232
simplicity, 232
suitable lock, 233

396

INDEX

Safety lamps (construction of),
219

bonnets, See B.

chimneys, See C.

essential parts of 1., 218

extinguished by opening, 283-4

flame set high in L, 232, 304

gauzes. See G.

glasses. See G.

Gray inlet tubes, See G., etc.

hood. See Bonnet.

igniter. See I.

locks, See L., etc.

parts, depend on each other,
232, 278

pricker, 304

small sizes, 236

heat quickly in gas, 236
often preferred, 236
xinsafe in gas, 236

standards, See S., 1.

wicks, See W.

wick tubes, See W. t.
Safety lamps (general work).
Types of,

Ashworth, 250,

Hepplewhite-Gray,

252, 330

Beard deputy, 257

Mackie, 273

Cambrian, 245

Clanny. 240, 330

Davy, 234

, Scotch, 238

Evan Thomas, 237, 243, 245

• ' Geordie ' ' (Stephenson) , 239

Gray, 248

Hughes, 237

Marsaut, 246, 330

Mauchline (Bull's eye), 245

Mueseler, 259

Protector, 296

Stephenson, 239

Thompson, 293

Wolf, 274
Safety lamps (history),

Ashworth-Gray 1. combined,
254

Ashwort h-Hepplewhite-Gray

combine, 257
Beard-Mackie sight indicator

first used, 324
Clanny, Davy, Stephenson, re-
lationship, 218

S'lfet}^ lamps (history) continued
Davy-Stephenson controversy,

221
Pieler 1. invention and use, 264
prohibition of Davy —

in Belgium, 236

— England and France, 236, 330

— Pa. bituminous, 236

s. 1. first used in mines, 217
standard wire gauze (Davy),
225
Safety lamp (principle and theo-
ry), 218
admission of air, See Chimney.

Eloin principle, See E: 1.
circulation in 1., See C.
conditions in 1., 222

artificial atmosphere, 267
extinction of wick flame, See S. 1.

(a. etc.)
flaming. See S. 1. (a. etc.)
flashing, See S. 1. (a. etc.)
free circulation. See C.
tendency to smoke, 231, 241, 244,

303
tendency to smoke, avoided, 245,
258

effect of bonnet, See B.

chimney, 224

Mueseler, 232

wire gauze, 219, 224

illuminating power, 305-7

photometry of, 287

principle of, 218
three-fold p., 219

protection,

mantle of burnt air, 223, 254
most danger at top, 222, 228
restricted discharge, 254

security, 228, 232, 238, 243

simplicity, 232
Safety lamp (use of),

by miners, 194-5

dangerous practices, See P., D.,

effect of canting 1., 232, 244,
250, 252, 262

effect of swinging 1., 244, 250

relighting 1. in mine, 276-7, 299
Saturation of air, See Air.
Scale measurement of flame caps,

Beard-Mackie lamps, 338, See
B-M. S. 1.

Chesneau lamp, 266, 338

Clowes lamp, 272, 337

Pieler lamp, 263, 338

INDEX

397

Scotch Davy, 238

cause of accidents, 239
dimensions, 238
favorite lamp, a, 238, 239
gauze not standard, 238
Screw-bolt lock, 281
Seal oil, 294

compared with vegetable o.,

299, 300
experiments, 299, 300
produces smoke, 294
uniform height of flame, 299,
300
Seismic disturbances,

relation to mine explosions, 212
Sensible heat, 51

Sharp gas, See G. (mine) classified
Shaw gas machine, 316
confusing results, 321
description of, 317-9
errors of m., 320
formulas to calculate per cent.

of g., 322
limitations of m., 322
methods of operating m., 321-3
working from higher explo, limit
321

working lower ,

322
indirect method, 323

not adapted to underground

work, 323
shows local condition too late,

324 *
standardizing the g., 319
use of, 320
value of, 323
Shaw's signal system, 315

condemnation of, 316
Shot firers,

lack knowledge of conditions,

196
requested fan stopped, 203
work of, 202
Sight indicator*, Beard-Mackie.

(See B. M., etc.)
Signal apparatus (for gas), 314

Shaw's s. system, 315
Singing of the coal, 117
Smoke gauze, 222, 240, 241, 244,

339
Smoke test for oils, 301
Soda, caustic, Use of, 185

Solids, 5

specific gravity of, to determine,
17
Special flames, 262
Special safety lamps, 262
Specific gravity, 16

calculation of, 30

s. g. of air, 31

— different gases, 31

flashdamp, 128

difference in calculated result,

31
different substances (table), 22
examination questions, 40
examples, 24-5
methods of determining, 17

by a balance, 18

— the hydrometer, 20

of different substances (table),

22
of mine gases (tables), 3, 49, 124
relation to atomic weight, 22

density, 16

use of to find weight, 23

rule for gases, 23

solids and liquids, 23

Specific gravity bottle, 20

Specific heat, 48

constant pressure; c. volume,
50
ratio of (1.405), 51
definition, 49
effect of temperature, 50
expresses heat units, 49
of air and gases (table), 49

Specific volume, 15

Spedding steel mill (fire wheel),
216

Spermaceti, 290

Sperm candles, 290, 297

Sperm oil,

adulteration of, .in market, 294
compared with vegetable o., 295
how derived, 294
illuminating powers, 294
incrusts wick little, 294
mixed with petroleum, See P.,
M.of

Spontaneous combustion, 62, 154
causes, 154-5

in abandoned workings, 155
theory of, 154-5

398

INDEX

Spraying in mines, 192. (See M.
air.)
cools air, 192
injudicious s. an evil, 192
pipe line system, 194
relation to m. explosions, 168, i
192 I

Sprinkling in mines, See Spraying, '
etc. I

Squibs, use in blasting, 201 i

Standard A-H-G lamp, 256 |

Standard barometer reading, 83,
86, 91. (See B. r.)

Standard candle, 290, 297
Standard flames, 290

in lamps, 264, 272, 324

— testing, 334
Standard wire of B-M. sight indi-
cator, 274, 324
Standards, inconsistency in, 91
Standards, Lamp, 220, 231

hollow t'ubes? 248. (See Gray
inlet t.)

movable, to lock bonnet, 245

thin, No. 7 wire, 256 •
Standards of w eight and measure,
353. (See Gallon, Kilogram,
Liter, Meter, Pound and
Yard.)

conversion tables, 360-1

fundamental equivalents, 359

history of, 353

uniformity of, 353, 362

unit weights (table), 363
Standards, Artificial, at —

American Bureau, Washington,
353, 359

Archives, Paris, 358

International Bureau, 358

new s. made and distributed,
358
Standards, Legal,

compared, 354-5

English gallon, 354-5

United States, 359
Standards, Natural, 353

meridian quadrant, 353

seconds pendulum, 354

Standards, Specific-gravity,

air, for gases, 23

water for solids and liquids, 23
Steel Mill (fire wheel), 216

Stemming in blasting, 202

Stephenson lamp, 219, 239
oil burned, 240
original 1., 219, 239
present 1., 240
principle of S. 1., 219
tested in blower, 219, 239

Stimulants, use of in rescue work,
109

Stinkdamp, See Hydrogen sul-
phide.

Stokes (alcohol) lamp, 267
alcohol 1. detachable, 268
A-H-G. 1. adapted, 267

Stopping ofT mine fires,
order of building s., 157
removing s., 157-8

Stratification of gas, 115, 334

Sulphureted hydrogen. See H.
sulphide.

Sulphuric acid used to purify oil,
294

Summer rape (oil). 293. (See R.
oO

Surveyors' lamp, 246

Symbols, Chemical, 25
of elements (table), 8
— mine gases (table), 3, 49

Symptoms of poisoning (gas),
carbon dioxide, 186

monoxide, 108, 182

hydrogen sulphide. 111

Tables, See Index to tables,

XIIL
Tallow candles, 290

high illuminating power, 297
Tanks for filling safety lamps, 278,

350
Temperature,

absolute, see A. t.
adiabatic change. See Abso-
lute t.
atmospheric t.,See At-^rs^l e^e.
effect of chemical heat, See

C. h.
effect on barometer reading, 83
density, air or gas, 115

— saturation of air, 92,

206

INDEX

399

Terrperature, continued

measurement of, 42. (See

Thermometer) .
of air (mine). See M. a.

— combustion, 66
calculation of, 6G-7
constant pressure, 69
volume, 69

— explosion,

different explosives (table), 200
mine gases, calculated, 67. 213

— flame, theoretical, 69, 151.

(See F.)
of heated wire — lighting fuse,

202
of ignition (gases), 149

compared with t. of combustion,

69
necessary to i., 147, 148, 171

relation to change of state, 11

heat, 42

Test chamber for lamps, 326
Testing for gas (in mines), 308
acquaintance with lamps and

oil, 336
conditions vary suddenly, 223,
334
slight -changes detected, 258, 329,
335, 343

early practices, See P., E.
flame test, 331

cap test, 341

compared with sight indicator, 343

fails to show gas, 134, 229, 334,
341

height of lamp flame, See F. (1.)

guessing percentage of g., 229,
334, 341

interpreting flame caps, 336

judgment, lack of, 194, 258

making the test, 341

at time and place of danger, 324
gas pocketiin roof, 341
unnecessary refinement, 334

reports "no gas," 229, 334, 343,

344
small percentages, detecting,

need of, 230, 334

volatile vs. ordinary oils, use of,
335
thin layer of g. at roof, 341-2
volatile oil, use of See V. o.
wronjT stystem of testing, 344
Testins for gas indicators), 308
^ee Indicators, Gas)
(See Beard-Mackie Sight I.)

Testing for gas (indicators), con-
tinued
dust in air shown, 344
normal flame, 258, 329, 330,.

338, 343
platinum wires,

B-M. sight indicator, 258, 274, 325
Liveing indicator, 311
sight indication, 258, 274, 329,

343
small percentages of g.,

B-M. sight indicator, 230, 325, 329
Liveing indicator, 312

Testing for gas (lamps), 331
(See Flame cap)
(See Testing 1)

air-current, protect 1. in, 264,

343, 345
danger of —

explosion, close bonneted 1., 223
flaming, large gauze (Pieler), 264
flashing, reUghting (volatile oil),

230, 276, 299
unsuspected gas, 330, 346

detecting small percentages of

g., 230, 264,274,334
explosion in 1., 223, 346

balloons of flame, 223
flame, (See T. foi- g. in mines)

action in gas (flaming), (See Safety
1., a. etc.)

adjustment of, See F. (lamp)

alcohol f.. See F. (a.)

candle f., 215, 331

extinction of, See Safety 1. (action,
etc.)

hydrogen f., See F. (h.)

normal f., 341

reduced f., 330, 338, 341

special f., 262

standard f.. See S. f.
lamps.

See Safety I. (action in gas).

(care of).

making the test (Davy), 341

caution needed, 341, 346

flaming, move carefully, 347

holding 1. upright, 342-3

preparing the 1.. 339

turning 1. on side, 342

thin layer of g. at roof,

disturbing- the g., 342
turning 1. on side. 342
use of Gray inlet tubes, 248, 254

Testing for gas (other means),
bird test, 107
blood test, 107
collecting gas in —

bags, .324

small hand bulb, 313

mouse test, 107, 143, 182

400

INDEX

Shaw gas machine, See S. g. m.

signal apparatus, See S. A.
Testing lamps, Types of,

Ashworth, 250, 269

Hepplewhite-Gray,

254-5 ^'

Beard deputy, 258

. Mackie, 273

Chesneau, 265

Clowes, 270, 337

Davy, 235, 333

Eloin, 332-3

"Geordie," 240

"Gray," 248

Hughes, Evan Thomas, 238

Pieler, 262

Stephenson, 240

Stokes, 267
Testing oils,

for purity, 294

• — flashing point, 296

open test, 296

practical test in mine, 301

smoke test, 301-3
Testing safety lamps, 226
means adopted, 226
need of, 226, 233, 348
wrong method, 233
Thermometers, 43-4
scales in use, 42

comparison of, 43
examples for practice, 72
formulas for conversion, 44

Theories,

atomic t. (Dalton's), 5, 10, 14

coal dust t., 171

earth breathings, t. of, 208

explosives, t. of, 152, 199

flame, t. of, 289

percussive t., 172

spontaneous combustion, t. of,
154

Stephenson lamp, t. of, 219
Thompson's acetylene lamp,

illuminating power, 293

interchangeable oil vessel, 293

not easily extinguished, 293
Tin-can Davy lamp, 235
Touchpaper, use of in blasting,

201
Transmission of heat, 46

Transpiration, 13. (See Gases, m )

laws of, 118

rate of (table), 119

velocity of, See V., etc.
Treatment of persons overcome
by —

afterdamp, 182-3

carbon dioxide, 110

monoxide, 109

hydrogen sulphide. 111

nitrous oxide, 113
Turnip, Oil derived from, 293

Units of heat, 47

British thermal u.. See B. t. u.

calorie, 47

pound-calorie, 47
Units of length, weight, and vol-
ume, 354

(See Standards, etc.)

different countries,
England, 356
France, 356
United States, 356

fundamental values, 359 .

weights of unit volumes, 363
Units of reference, 362. (See
Constants. )

Vapor,
aqueous (water) v.,

in air, See A.

heat of formation, 52

lighter than air, 93

mixture of gases and v., laws of, 93

pressure (tension) of, 93; table, 95

specific gravity, 49, 93

heat of, 49; varies, 50

weight of in air, formula, 94

explosive vapor in lamps, 230
mercurial vapor in mines, 133
mixture of gases and v. , laws of,
93
Vaporization, (See Evaporation.)
heat of, 52

of bitumen, etc., in mines, 147
— oil in lamps, 267, 299

INDEX

401

Vaseline, use of in rescue work,
185

Vegetable oils, 293

compared with mineral o., 298

seal o., 299

experiments with, 299
flashing point high, 296
illuminating power, 295
incrustation of wick, 294
kinds of,

colza, See C. o
rape, See R. o.
mixed with petroleum See P.,

etc.
refined v. o., 299
source, 293
Velocity of diffusion, gases, (See
D.)
effects composition of g. mix-
ture, 124-5
formation of flashdamp, 127
Velocity of transpiration, gases,
(See T.)
affects composition of g., 102,
119
Violent outbursts of gas, 121

Morrissey, B. C, 147
Viscosity, 12
Volcanic activity,

relation to mine explosions, 208
Volatile oils, 295. (See Illumi-
nants)
compared with other i., 335
flashing point low, 291
give higher flames and f. caps,

332
cotton in oil vessels, See C,

etc.
danger of, 230, 276-7, 292,

296, 299
extinguished easily, 230, 264
kinds of, (.:ee I., special)
alcohol, benzine^ benzoline
colzaline, gasoline, naphtha.
use in testing,

sensitive flame, 230, 263, 266, 332,

3.35
unreliable results, 267
vaporize in lamp, 267, 299
Voltage of incandescent lamps,
160

Volume, 10
change of,

adiabatic. 39, 60, 214
calculation of, 38. 213
due to chemical reaction, 36
effect on pressure, 39, 214
determined accuialely by

weight, 354
law of V. — Avogadro's, 15
of air per pound of dust, ren-
dered explosive, 174
of flame, 69, 152

— gas in coal. See C.

produced by explosives,

153-4

percentage composition by v.,
34

relation to pressure, See Abso-
lute p.

— temperature. See

Absolute t.

Water,

standard for weight, 23, 354
density of distilled w., 357
formula to calculate, 357
weight per unit volume, 363

weight of, in air. See A.

air-current, 207

not accurately de-
termined, 354
assumed weight English standard.

354-5
assumed weight French standard,
355

Watering in mines, See Spraying,

etc.
Water vapor, See V.
Wax candles, 290

illuminating power, 297
weight of w. burned per hour,
297
Weight, 14

atomic w. (See A. w. )
calculation of, rule, 23
of air,

formulas to calculate, 76-7
how determined. 75

— different substances (table),

— moist air, formula, 94

— moisture in air, formula, 94

— water in air-current, 20"

402

INDEX

Weight, continued

percentage composition by w.,
32

unit of w., 14

w. of common standards,

362-3
Westphalian rescue corps, 183
Whale oil, 294

W hitedamp, See Carbon monoxide.
Wicks (candle),

plaited, 297

snuffing the w,, 297

effect of, 297

means to reduce a., 297

Wicks (lamp), 303
care of,

keep clean, 279. 304, 305
preparing round w., 304
renew often, 304, 339, 349

kinds of,

flat w., 269. 303
round w.. 303

operation in lamp,

by screw, 27,7

— toothed wheels, 251

held in sheath, 277

stationary w., sliding sheath, 286

troubles,

burning at slot, 300
chars quickly (rape oil), 299
gumming, 304, 339
incrusting. 294, 299, 305

Wick tubes, 303
corrugated, 304
vent for air, 304
Windy shots, 198. (See Blasting,
etc.)
increase explosive conditions,
137
Winter, rape, 293, (See R. oil)
Wire gauze, (See G., Lamp)
experiments of Davy, 225
heated low red passes flame, 225
temperature of wire, 202

Wire gauzp, continued
influence of w. g., 224
principle, theory of, 224-5
standard mesh (Davy), 225
finer mesh used, 266

Wire, heated, used to light fuse,
201 2

temperature of w., 202

dangerous practice, 202
Wolf lamp, 274

burns 70-degree naptha, 278

construction of, 277

cotton in oil vessel, 277, 278,
279

filling the 1., 278-280

inserting the cotton, 279
tank for f. the 1., 279
weight of cotton used, 277

friction igniter, 274
danger of, 276-7

illuminating power, 280, 306

magnetic lock, 284

principal features, 280
Working lamps, (See Safety 1.,
etc.)

not good testing l, 227, 332

ownership of, 345

proper height of flame, 345

requirements of, See S. 1. (clas-
sification).

types of, See S. 1. (g. w.), T. of.
Workings, Abandoned, See A. w.
Workings, New, gas in, 117

Yard, Standard,
derived, how, 353-4
English, 353, 356
United States, 356

305

B36

Beard, James Thorn

Mine gases and explosions

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