198 



NA TURE 



\_ncc. 31, 1885 



In the beginning of the year 1S75 I removed to South Wales, , beginning of 1876, and was referred to in my first paper (1876) 

 and soon discovered thit all the coUieries in which great ex- ■ thu; ; "It would be premature to draw any positive inference 

 plosions had occurred were dry and dusty. My previous . from my experiments with gunpowder shots, as they are by no 

 experience was almost wholly confined to damp mines, in all of ] means so satisfactory as I could wish, and I am glad to be able 

 which, with one exception (Xitshill), there was no coal-dust, ] to state that Prof Marreco, of Newcastle-on-Tyne, intends to 



and in none of which, with the same exception, a great explosion 

 had ever occurred. The impression referred to above probably 

 exercised a certain influence at that time in helping me to 

 form the conception of what I believe to be the true explanation 

 of great colliery explosions. In the words of my first paper ' 

 it is as follows : " If it could be shown that a mixture of air and 

 coal-dust is inflammable at ordinary pressure and temperatu 



investigate this question with more substantial apparatus." 



Returning to Sir Frederick's remark, I would say that I 

 abandoned no previous conclusion "in favour of one some time 

 previously accepted by Marreco." I then held, and still hold, what 

 is now a universally accepted opinion amongst mining men, that 

 a mixture of air and fire-damp, which is not inflammable at 

 ordinary pressure and temperature, may be rendered inflamma- 



thcre would be no difficulty in accounting for the extent and j ble by the addition of dry coal-dust, and I was prepared, as soon 

 violaice of many explosions which have occurred in mines in as proof satisfactory to myself was forthcoming, to extend the area 

 which no large accumulations of fire-damp were known to exist ; 1 of my opinion, so as to include a mixture of fine dry coal-dust and 

 for it is only necessary to suppose that a violent gust of wind air in the same category. This latter proof alone was necessary 

 {originated, for example, by the explosion of a small accumula- 1 to the firm establishment of the theory enunciated aj^ the cony 



tion of fire-damp) had swept through the adjoining galleries, 

 raising a cloud of dust into the air, and then all the other 

 phenomena would follow in regular order. The flame of the 

 originally inflammable mixture would pass into the newly 



encement of my first paper, and for that reason Sir Frederick's 

 statement appears to me to be wanting in logical sequence. 



>i either the statement made by Marreco and Morison, that 

 they intended to "endeavour to discover whether coal-dust 



formed one, expanding its volume ; the disturbance would be 1 could by any means be exploded in an atmosphere totally free 



propagated over an ever-widening area, until that area might 

 possibly become co-extensive with the workings themselves ; 

 and /he coi!s:quences would be the sain; as if the whole space had 

 Ih'cn filled wi'.h an inflammable mixture before the disturbance 

 began." 



I demonstrated by an experiment first made on the 3rd of 

 July, 1S75, that air containing less fire-damp than can be 

 detected by the ordinary means of testing the air in mines, is 

 rendered inflammable at ordinary pressure and temperature when 

 fine dry coal-dust is added to it. This was the first step towards 

 proving the truth of my theory. 



In the same paper I also stated, " It is alwa)'s possible that 

 if coal-dust could be m.ade fine enough and were thorouglily 

 mixed \vith dry air in the proportion of ab :)ut I pound to 160 cubic 

 feet of air, the mixture might be inflammable at ordinary 

 temperature, or, if not, it might at least be so nearly inflam- 

 mable that an explosion begun in it, in a confined space, might 

 be jjropagated through it." 



In iny second (1879) and subsequent papers to the Roy.al 

 Society, I stated the further opinion, first, as the result of more 

 elaborate experiments, and secondly, as the result of a careful 

 parson.al investigation and consideration of all the circumstances 

 attending the occurrence of several great explosions, that, " -V 

 fire-damp explosion occurring in a dry coal-mine is liable to 

 be indefinitely extended by the mixture of air and coal-dust 

 produced by the disturbance which it initiates." This was the 

 final step. 



Of this. Sir Frederick says : ^ " Mr. Galloway was cer- 

 tainly the first to enunciate the conclusion that a small pro- 

 portion of fire-damp is essential to impart to a mixture of air 

 and coal-dust the power of propagating flame, though he 

 afurioards abandoned this conclusion in favour of the one some 

 tint' prei/iously accepted by Marreco, to the effect that fire-damp 

 is altogether unnecessary for the conveyance of flame with 

 explosive eftect by a mixture of dry coal-dust and air." 



In January, 1878, I commenced a series of articles in Iron on 

 coal-dust explosions, hoping thereby to arouse an interest in the 

 subject, and, amongst other items of information, I gave trans- 

 lations of Vital's and Desbief and Chansselle's papeis. Seven of 

 thes';; articles had already appeared when, in April, 1878, Prof. 

 Marreco (to whom I had myself sent copies of them) and Mr. 

 Morison, read their first paper before the Chesterfield Institute. 

 They say, " Before the writers had the opportunity of learnin 



from fire-damp," nor the results of the experiments published by 

 them, appear to me to warrant Sir Frederick in taking up this 

 position ; for, concerning these very experiments of Prof. Marreco's 

 he had himself remarked in the year iSSo:^ "It does not 

 appear that in the numerous experiments made at Harton 

 Colliery by the exposure of naked flames in currents of air 

 laden with coal-dust, and by firing small cannon (rejiresenting 

 blown-out shots) placed in various positions in such air-currents, 

 anv indication has been obtained of a propagation of flame by the 

 coal-dust." How then could Marreco have concluded that "fire- 

 damp is altogether unnecessary for the conveyance of flame 

 with explosive eftect in a mixture of coal-dust and air" ? 



Sir Frederick continues to say, regarding myself: " Even his 

 latest publication on the subject tends in the same direction, 

 and emphasises his desire to ' claim that no earlier author had 

 gone the length of crediting coal-dust with the role of principal 

 agent, and relegating fire-damp to a secondary position.' The 

 more recent results of other writers in this direction have, 

 however, conclusively demonstrated that this is far too great a 

 length to go, and that while on the one hand a very fine dry 

 and highly inflammable coal-dust may, when raised and mixed 

 with air by the force of a blown-out shot, become inflamed, and 

 may then carry flame to considerable distances with a rapidity 

 .and violence of action similar to that of a fire-damp explosion, 

 the e.xtent to which, on the other hand, flame is propagated 

 under corresponding conditions by most descriptions of coal-dust 

 in the complete absence of fire-damp is very limited. " 



Sir Frederick and those whose opinions he here quotes appear 

 to have omitted to take one element into consideration which 

 has an important bearing upon the case. To this I may have 

 occasion to refer more particularly at an early date. 



\V. Galloway 



Sunset-Glows 



I WISH to call the attention of observers to a peculiar pheno- 

 menon which has been frequently noticed by me lately in con- 

 nection with these sky-scenes. A very bright after-glow was 

 visible here on October 27 Last. I believe the date is correct, 

 although I have unfortunately mislaid my day-book ; the facts, 

 however, I can vouch for otherwise, as they were detailed at 

 the time. At 5 p.m. a heavy bank of cumulus was to be seen 

 extending along the south-western sky-line, about 5° above and 

 what had already been accomplished abroad, their attention closely parallel to the horizon. High over this bluish bank of 

 was directed to the subject by a paper read by Mr. W. cloud rose the yellow haze of departing sunlight. This diffused 

 Galloway before the Royal Society, in which he related his after-glow was plainly intersected by numerous (I counted 

 experiment in producing explosion in a mixture of fire-damp twenty-two) delicate streaks of nebulous stratus. These inter- 

 and air impregnated with dust. The opinion expressed in that , secting lines (they were scarcely "bands") were horizontal and 

 paper, viz., that coal-dust was explosive only in an atmosphere ' parallel, piled up, as it were, above one another as high as 25 



containing a minute proportion of fire-damp, induced the writers 

 to still further extend the scope of the experiments, and 

 endeavour to discover whether coal-dust could by any means be 

 exploded in an atmosphere totally free from fire-damp." 



The arrangement to carry out the experiments here spoken of 

 was made between Marreco and myself ia the end of 1875 dr 



>/o, 



from the' sea-line. The lowest hung apparently about half a 

 degree above the gilded upper edge of the dark cuumlus. On 

 November 4, just before sunset, I exposed a gelatine pl.ate, and 

 succeeded in obtaining a photograph, in which seven of these 

 narrow horizontal cloud-streaks can be faintly seen. On De- 

 cember I the following note was made : — 4.20 p.m. Wind light, 



' Report on ttie Results of Experiments made witli Samples of Du 

 iat Sealiam Colliery, &c.," 1880. 



t col- 



