NA TURE 



183 



THURSDAY, APRIL 24, 1913. 



CHEMISTRY OF COAL MINING. 



(1) Coal, and the Prevention of Explosions and 

 Fires in Mines. By Dr. J. Harger. Pp. vii + 

 183. (Newcastle on-Tyne : Andrew Reid and 

 Co., Lid. ; London : Longmans, Green and 

 Co., 1913.) Price 3s. 6J. net. 



(2) Safety in Coal Mines: a Text-book of Funda- 

 mental Principles for Firemen and other 

 Workers in Mines. By Prof. D. Burns. Pp. 

 vi+138. (London: Blackie and Son, Ltd., 

 1912.) Price 2s. 6d. net. 



(ij T N the first of two papers read respectively 

 JL on February 27 and October 8, 1912, 

 before the Manchester Geological and Mining- 

 Society, Dr. Harger expresses his views regarding 

 a means of preventing the occurrence of explosions 

 as follows : — 



"The dry mines in this country are more dan- 

 gerous than they were several years ago, and are 

 likely to become more so in the future if the 

 Government has its way ; . . . a reduction of 

 1 per cent, in the oxygen content, and the addi- 

 tion of ^ per cent, of carbon dioxide in the ven- 

 tilating current, is all that is required for most 

 mines ; and for the more dangerous mines ... a 

 reduction of 2 per cent, in the oxygen content and 

 the addition of about f to 1 per cent, of carbon 

 dioxide would make the intake airways absolutely 

 safe." 



In the second paper Dr. Harger suggests the 

 same means for preventing "gob-fires" (spon- 

 taneous combustion). His book is an elaborated 

 edition of both papers, prefaced with some chapters 

 on the nature of coal and its occluded gases, com- 

 bustion, respiration and the mechanism of explo- 

 sions. 



It is self-evident that if the proportion of oxygen 

 in the air of mines can be reduced in practice to 

 such a point that it cannot support the combustion 

 of either firedamp or coal, neither explosions nor 

 gob-fires could happen. But it is unfortunate that 

 whatever intrinsic value our author's proposals 

 may have — and few would be rash enough at this 

 stage to say they have none — they are based partly 

 upon erroneous impressions regarding the pheno- 

 mena of great explosions, and partly on the results 

 of what appear to be faulty experiments con- 

 ducted on too small a scale. 



Great explosions do not, as Dr. Harger 

 imagines, travel either exclusively or generally 

 against the direction of the ventilating currents; 

 and they do not avoid the working faces or return 

 airways because, as he imagines, the air in these 

 NO. 2269, VOL. 91] 



places already contains too little oxygen and too 

 much carbon dioxide to admit of its supporting 

 the combustion of coal-dust. 



With regard to the first point, the shot which 

 originated the explosion at Altofts Colliery, to 

 which he refers, was fired in an intake airway at 

 .1 distance of 550 yards from the bottom of the 

 downcast. The flame traversed all the intake air- 

 ways but one, at the entrance to which it was 

 arrested by dampness, and in every case (except- 

 ing only in the 550 yards) in the same direction 

 as the air-currents (Proc. Roy. Soc, vol. xlii., 

 p. i 74 ).i 



With regard to the second, it was shown 

 (Proc. Roy. Soc, vol. xxviii., p. 416) that return 

 air saturated with, and carrying visible globules 

 of, moisture caught fire at a naked light and 

 burned with a large flame when mixed with a 

 certain coal-dust. That coal-dust came from a 

 colliery adjoining Ferndale, and was of the same 

 quality, so far as volatile matter is concerned, as 

 the pare Ferndale dust with which our author 

 failed to get an ignition in his apparatus with 

 normal air. This fact, coupled with the further 

 one that two great explosions have happened at 

 Ferndale colliery — one in 1867 with 178 deaths, the 

 other in 1869 with fifty-three deaths — seems to show 

 that the experiments are not wholly trustworthy, 

 and that some of the conclusions drawn from 

 them as to the quality of air required to prevent 

 ignition will have to be modified. 



Dr. Harger proposes to effect his purpose by 

 mixing the necessary proportion of flue gases, 

 which emanate from the boiler furnaces found at 

 every colliery, with the intake air, after having 

 passed them, while still hot, over some catalytic 

 material such as bog iron ore, oxide of copper, finely 

 divided metallic copper, and so on. He contends 

 that if they were thus treated the residual oxygen 

 contained in them would combine with the carbon 

 monoxide, hydrocarbons and smoke, and render 

 them innocuous ; and he quotes the authority of 

 Dr. J. S. Haldane and others to show that air 

 of the required quality is not only harmless, but 

 healthful. 



His proposals have the distinguishing merit of 

 originality, and have been set forth with such 

 vigorous insistence both in his book and in his 

 papers that they cannot fail to command atten- 

 tion. 



(2) This book is designed to meet a want 

 created by the Coal Mines Regulation Act (191 1), 



1 Now that this question has assumed some importance it is perhaps rather 

 unfortunate that the Koyal Society did not publish the whole of this paper 

 (which is a description of Altofts explosion) as well as the plan of the work-, 

 ings which accompanied it. as some of the misu' derstandings and contro- 

 versies which have a-isen during the last twenty-five years might have been ■ 

 thereby avoided. 



1 



