438 



NATURE 



[April I, 1875 



accidents, and that the practice of employing "firemen" just 

 referred to is a highly perilous one. 



There can be no question that the comparatively dim light 

 afforded even by tlie best constructed lamjis in general use is a 

 cause of great temptation to the men to use uncovered lights ; it 

 is therefore much to be hoped that continued efforts may be 

 made to apply the electric light to the illumination of mine 

 workings. Some approach to success in this direction was already 

 attained ten years ago, and one cannot but have great faith in 

 the ultimate feasibility of some portable method of illumination 

 by electric agency. 



There are, however, causes other than the use of unprotected 

 lights, which contribute to the production of coal-mine explo- 

 sions. Efficient ventilation of workings, whether in use or not, 

 whereby all dangerous accumulation of fire-damp is avoided, and 

 any sudden eruption of gas may be rapidly dealt with (the gas 

 being largely diluted and swept away as speedily as possible), is 

 indispensable to the safj working of the mine (without any refer- 

 ence to the health of the men) so long as there is any temptation 

 for the use of naked lights. The original laying out of a working 

 greatly affects the question of efficient ventilation, and explosions 

 have been clearly traced to gas accumulations, which there was 

 sufficient power of ventilation to reduce, if the nature of the 

 working had admitted of its proper application. In arranging 

 for the efficient ventilation of a mine, ample provision for rapidly 

 applying extra artificial ventilating power should be made, and, 

 in connection with this, the interesting and useful series of 

 observations should be Ijorne in mind which have been made 

 public in communications tn the Royal Society and the Meteoro- 

 logical Society by Messrs. R. H. Scott and W. Galloway.' 



Since the employment of gunpowder as a means of rapidly 

 removing coal, or overlying shale, has come into considerable 

 use, there can be no question that an additional and a very 

 serious source of danger has been imported into the working of 

 collieries. That the explosion of a charge of powder in a blast- 

 hole, or the " firing of a shot," has by no means unfrequently 

 resulted in tlie production of a fire-damp explosion, has been 

 clearly established by careful inquii-y. This has been ascribed 

 to two causes, one of them the direct ignition of the explosive 

 gas-mixiure by the flame from the shot, the other the dislodg- 

 ment of fire-damp from cavities or disused workings by the con- 

 cussion produced, and its ignition by some naked flame or 

 defective lamp in the neighbourhood. If a shot takes elTeet pro- 

 perly (i.e. if the force is fully expended in breaking the coal or 

 rock at the seat of the charge), there is seldom flame produced, 

 but if the tamping which confines the charge in the bIa~t-hole is 

 simply blown out of the latter like a sliot from a gun (which not 

 unfrequently occurs when the rock is very hard or the tamping 

 is not sufficiently firm, or when the cliarge of powder is exces- 

 sive), the powder-gas issuing from the blast-hole will produce a 

 flash of fire as obtained with a gun, and if the fire-danip were in 

 the immediate neighbouihood, it would no doubt be ignited 

 thereby. But this combination of conditions is not likely fre- 

 quently to occur ; the second cause above given is therefore more 

 likely to be fruitful of accidents ; but the existence of a third 

 cause, to which the majority of explosions connected with blast- 

 ing in collieries is most probably ascribable, has been very clearly 

 established by the careful inquiries, sound reasoning, and inge- 

 nious experiments of Mr. W. Galloway, Inspector of Mines. 

 Mr. Galloway conceived, and has clearly established by experi- 

 ments in the laboratory and in coal-pits, that the sound-wave 

 established by the firing of a shot (especially by the sharp explo- 

 sion produced when tlie tamping is shot out of a hole) wdl by 

 transmission, even to very considerable distances, have the effect 

 of forcing the flame of a safety-lamp through the meshes of the 

 gauze, and will thus lead to the ignition of an explosive gas- 

 mixture surrounding the latter, f It may be hoped that the 

 miner may be trained to a knowledge of the danger he incurs 

 by the incautious use of gunpowder, although the persistent reck- 

 lessness with which he sacrifices safety to comfort, in despising 

 the use of the safety-lamp, forbids sanguine expectations in this 

 direction. 



Reference has not been made to another very possible source 

 of accidents due to the employment of gunpowder for blasting 

 purposes, namely, carelessness in the keeping and handling of 

 the explosive agent by the men. Personal observation by the 

 lecturer of the reckless manner in which powder is frequently 

 dealt with in mines, leads him to believe that this contributes 

 its quota as a cause of colliery explosions. 

 * Nature, vol. v. p. 504 ; vol. x. p. 157. t Nature, vol. x. p. 224. 



The accidents in collieries have their parallel in domestic life, 

 in coal-gas explosions, which, though at first sight of compara- 

 tively small im]:iortance if judged by the loss of life and property 

 which they occasion, yet merit serious consideration on account 

 of the great frequency of their occurrence, and the demonstra- 

 tion which they almost always afford of ignorance or culpable 

 carelessness. 



The circumstance that the admixture of even minute quantities 

 of coal-gas with air can be at once detected by the unmistakable 

 odour of the gas, should serve as a safeguard against accidents ; 

 unfortunately, however, thoughtlessness or want of knowledge 

 frequently causes this very fact to lead to the opposite result. 

 Escapes of gas in comparatively small quantities often occur at 

 the point of union (generally by a ball-and-socket joint) of a 

 hanging burner or chandelier with the gas-pipe, or at the tele- 

 scope-joint of such gas-filtings ; the column of water required in 

 the joints to confine the gas becoming very gradually reduced by 

 evaporation. In such instances an explosive mixture will accu- 

 mulate in the upper part of the apartment of which windows and 

 doors are closed, while the air in the lower part will continue 

 for a long time free from any dangerous admixture of gas ; and 

 instances are continually recorded in the public prints of the 

 deliberate ignition of such explosive mixtures, by persons who, 

 observing the smell of coal-gas upon entering the room, proceed 

 forthwith to search for the point of escape by means of a flame. 

 It need scarcely be staled that such a test is a perfectly safe one 

 in itself, and that if the acceptance of the warning given by the 

 odour of gas in the lower part of the room were promptly fol- 

 lowed by the simple precautionary operation of leaving open for 

 some time all wmdows and doors, so as to afford ready ingress 

 of fresh air, and thus speedily expel, or very largely dilute, 

 the gas-mixture, the leakage could be looked for with no risk 

 of accident. 



Gas explosions, generally of a serious" nature, do occasionally 

 occur through no fault of those who are the direct agents in 

 bringing them about, as by a person entering with a light a 

 closed apartment in which there has been a very considerable 

 escape of gas for some time, or a building in which gas has been 

 entering from a leakage in the supply-pipe or the main. 



The employment of illuminating agents closely allied to coal- 

 gas, namely, liquid carho-hydrogen compounds obtained by the 

 distillation of coal or shale, or derived as natural products from 

 coal-bearing strata, gradually extended during the earlier part 

 of the last quarter of a century until they became formidable 

 rivals of mineral and vegetable oils and even of gas itself 



The several varieties of so-called petroleum spirit which are 

 known as naphtha, benzine, benzoline, gasoline, japanner's spirit, 

 &c. , yield vapour more or less freely on exposure to air at ordinary 

 atmospheric temperatures, and even in some cases below 50° F. 

 Although much the largest proportion of the petroleum spirit 

 employed is probably used in lamps of some form or other, there 

 are other important uses to which it is applied in large quantities, 

 especially in various industries. 



The so-called paraffin- or petroleum-lamp explosions, of which 

 in the earlier days of the employment of these illuminating agents 

 ihere were so many recorded in the newspapers, and of which 

 one still hears occasionally, were, with very few exceptions, not 

 correctly designated as explosions, and when they were so, were 

 not caused by the employment of the volatile oils or petroleum 

 spirit. As these vaporise very freely at the slightly elevated 

 temperature which a reservoir of a lamp soon attains, air is 

 either entirely expelled from the latter by the vapour, or so 

 diluted by it, that the mixture is not explosive. If therefore 

 flame can have access to vapour escaping from any opening in 

 the reservoir near the wick, in a badly-constructed lamp, it will 

 merely burn as it escapes. If a lamp charged with petroleum 

 spirit be carried incautiously, or accidentally jerked so that the 

 liquid is suddenly brought into contact with the warmer portion 

 of the lamp, near the flame, a very rapid volatilisation may thereby 

 be caused, resulting in a conbiderable outburst of flame. 



If a petroleum oil which has been imperfectly refined, and 

 which, therefore, contains some proportion of the very volatile 

 products, or spirit, be employed in a lamp, a slight explosion 

 may be caused by its yielding up a small amount of vapour at 

 the temperature to which the reservoir becomes heated, and thus 

 producing a feebly explosive mbiture with the air in the latter, 

 which may become ignited by the flame of the lamp. An explo- 

 sion thus produced is not at all of violent character, being 

 generally merely a feeble puft"; it may, however, cause the 

 cracking of the reservoir, and the consequent spilling and in- 



