132 



NATURE 



[September 22, 192 1 



Spontaneous Combustion in Coal Mines. 



'X'HE final report of the Departmental Committee 

 ■'• appointed by Mr. McKenna in 1912 "to inquire 

 into the circumstances in which spontaneous combus- 

 tion of coal occurs in mines, its causes and the means 

 of preventing it or of dealing with it," has now been 

 issued/ 



In form it is a model of what such a report should 

 be ; it opens with an historical review of the subject 

 from the seventeenth century, it proceeds to summarise 

 and analyse the scientific evidence collected during the 

 last ten j^ears, and then considers the conditions which 

 are found in practice to be conducive to spontaneous 

 ignition in coal-mines and the means of preventing or 

 extinguishing such fires. 



The question whether coal can ignite per se. or 

 whether this is effected through the hearing of an 

 impurity, e.g. iron pyrites, has long been in dispute, 

 the older opinion, both among practical men and 

 chemists, inclining strongly to the view that the 

 oxidation of pyrites is the primary cause of the 

 ignition. 



In an interesting quotation from Dr. Plott's 

 "Natural History of Staffordshire " (1686) we learn 

 that the shale and small coal left in the hollows of 

 old workings will fire "'natural of themselves," and 

 "have done beyond all memory." The seat of the 

 heating Is said to be a mixture of the "laming," that 

 lies between the measures of the coal, and the " sleek " 

 when "very much mixed with brass lumps." Plott 

 evidently leans to the pyrites theory, and quotes Dud 

 Dudley and Dr. Powers as vouching for the state- 

 ment that small coal and sulphurous sleek when 

 moistened and exposed to the air will turn red-hot of 

 themselves. The experience of mining engineers, who 

 found as a fact that fires mainlv occurred in seams 

 rich in pyrites (as in South Staffordshire) and were 

 absent in coalfields (such as the Durham field) where 

 the pyrites is very low — backed as this experience was 

 by the authoritv of chemists from Berzelius to Liebig 

 — led to the almost universal belief in pvrites being 

 the sole cause of ignition. Dr. Percv in 1864 seems 

 to have been the first to suggest that coal could itself 

 absorb oxygen and become heated, and this view 

 received much support from the experiments of Dr. 

 Richters, of Waldenburg, who showed that fine coal 

 with very little pvrites in it would absorb oxygen and 

 heat up, while the pvrites itself showed very small 

 absorption. The Roval Commission appointed in 1876 

 to inquire into the spontaneous combustion of coal in 

 ships regarded pvrites as the primary cause, but found 

 that the condensation of oxvgen on the surface and 

 the subsequent oxidation of the coal matter were 

 " contributorv " causes. 



.Since that date experiments in France, mainly those 



1 Departmental Committee on Spontaneous Combustion of Coal in 

 Mines. Final Keporl of the Deoartmental Committee on Spontaneous 

 Combustion of Coal in Mines. (Cmd. 1417). (London : H.M. Stationery 

 Office.) js. 6d. 



of Henri Kayol, and in Germany on the seam.s of 

 Upper Silesia (where fires are frequent), have shown 

 that the condensation and absorption of oxygen from 

 moist air by coal itself — especially when the coal is in 

 a thick layer — are the important factors in spon- 

 taneous combustion, while the oxidation of pyrites 

 (marcasite) is a less important factor. Up to the end 

 of the last century we may say that the pyrites theory 

 had the larger following ; but since the report of the 

 German Commission in 19 lo scientific opinion has 

 changed, and the opinion of practical men has been . 

 doubtful. i 



The verdict of the Committee — a body of men j 

 practically familiar with coal-mining — that they are I 

 satisfied on the scientific evidence brought before them j 

 that coal subject to spontaneous firing owes this pro- 1 

 perty, not to its pyrites content, but to the direct oxida- • 

 tion of the coal matter, should set at rest all reason- \ 

 able doubt and concentrate attention on the real \ 

 cause. That some heat may be generated by the j 

 oxidation of marcasite is admitted, but its direct effect j 

 is negligible. Where pyrites mav play a part is in j 

 the disintegration of coal whereby the latter mayj 

 become more permeable by air, and so more readily | 

 oxidised. . j 



In arriving at their conclusions the Committee was| 

 largelv influenced bv the experimental work of Prof." 

 Bedson, Sir R. Threlfall, Dr. Wheeler, and Dr. Hal- 

 dane, who were in close agreement ; and where there 

 still appeared to be some doubt, e.g. in the case of the 

 Bullhurst seam (North .Staffordshire) and in that 

 the Barnsley seam (Yorkshire), the Committee^ t 

 quested Dr. Wheeler to carry out special experiments 

 for them. These experiments are quoted in full and 

 appear conclusive. The Committee directs attention 

 to Dr. Wheeler's statement that the higher the oxygen 

 content of a coal the lower is its temperature 

 of self-ignition, and emphasise the practical im- 

 portance of the fact that a coal containing more 

 than 10 per cent, of oxygen is liable to inflammation 

 ■ — or, at all events, is suspect — whereas a coal con- 

 taining less than 6 per cent, may be regarded as non- 

 suspect. 



It is interesting to note that the work of the palaeo- 

 botanists is not neglected, and that the " fusain " of 

 Dr. Marie Stopes — the mother-of-coal — (shown by her 

 to be woody fibre) forms at its juncture with " vitrain " 

 — glance coal — the critical point of any piece of coal 

 with regard to inflammation — a conclusion which, 

 recalls Dr. Plott's statements as to the mixture of; 

 "laming" with "sleek." _ \ 



The remaining sections of the report deal with the^ 

 practical aspects of the subiect, and give manv tech- 

 nical suggestions for preventing and dealing with gob- 

 fires. One of the most imnortant points discussed is, 

 the practicabilitv of bvdraulic stowage — a certain cure 

 if it could be worked. 



Lighting of Factories and Workshops. 



IN 1913 a Departmental Committee was appointed 

 by the Home Secretary to inquire into the light- 

 ing of factories and workshops. The Committee 

 issued in 1915 an interim report containing much 

 valuable information which attracted much attention 

 and still holds a unique position amongst official 

 literature on this subject. On that occasion statutory 

 provisions requiring adequate and suitable lighting in 

 everv part of a factory and wo'-kshop were recom- 

 mended. Values of illumination were also prescribed 



NO. 2708, VOL. 108] 



in the interests of safetv and convenience, but de- 

 tailed recommendations on the order of illumination 

 necessary for various industrial processes were 

 deferred. 



The work of the Committee, suspended during the 

 later stages of the war, was resumed in 1920, and a 

 second report defining with greater precision the 

 phrase "suitable lighting" has recently been issued 

 (Cmd. 1418. id. net). The report deals specially with 

 the three factors of glare, shadow, and constancy. 



