NA TURE 



10-- 



THURSDAY, MARCH 6, 1879 



COAL AND COAL-MINES 



A Treatise on Coal, Mine-Gases, and Ventilation. By J. 



W.Thomas. (London : Longmans, 1878.) 



MR, THOMAS is known to chemists by reason of 

 the numerous and excellent analyses of the gases 

 inclosed in various coals which he published some time 

 ago in the Journal of the Chemical Society. Marsilly in 

 France, and Meyer in Germany, first broke ground on 

 this subject, but it is to Mr. Thomas, who very greatly 

 improved the method of research, that we owe our most 

 exact knowledge of the character of these occluded gases. 

 The matter is of considerable importance from a twofold 

 aspect. It not only serves to throw light upon the scien- 

 tific question of the formation of coal, but also affords 

 us information on the very practical question of the nature 

 of the influence of the atmosphere upon the deterioration 

 of coal. These observations attracted sufficient attention 

 from mining engineers and persons connected with 

 mining to induce, the author, to reprint them together 

 with other matter relating to the general subject, and the 

 result is the volume before us — a work which it is not too 

 much to say ought to be in the hands of the manager 

 and sub-officers of every colliery in the kingdom. Al- 

 though the subjects of gases in coal and of the deteriora- 

 tion of coal by atmospheric influences are treated at con- 

 siderable length, the relative or connected matter occupies 

 by far the greater portion of the book, and we have 

 chapters on the Diffusion and Transpiration of Gases, 

 Explosions in Mines and Ships, Combustion, Ventila- 

 tion, &c. 



The opening chapter is occupied by a discussion of 

 that most vexed of questions. What is Coal ? — a question 

 which has already cost some people much patience and 

 more money to get answered, but hitherto without success. 

 We are bound to say our author does not help us towards 

 a solution ; we are apparently as far off as ever from a 

 scientific definition of this everj-day commodity. His 

 remarks on the classification of coals are extremely just. 

 It is not surprising, from the author's connection with the 

 South Wales Basin, that the particular subject of anthra- 

 cite should receive special attention at his hands. The 

 origin of this form of mineral fuel has given rise to much 

 discussion in the past, but it is only within recent time 

 that the opinion that it is not necessarily the oldest transi- 

 tion-product in the decay or alteration of vegetable matter 

 has begun to gain ground. Our author throws consider- 

 able light on the process which has been at work in the 

 formation of anthracite, from a study of the composition 

 Tof the gases which are found inclosed in this class of 

 coal. He regards the process of the formation of coal 

 (after the first or primary decomposition which ensued 

 [during the time the vegetable matter was in the act of 



jing buried) to have taken place in four ways, viz. : — 



. The dry process aided by heat, leading to the pro- 

 duction of anthracite. 



I. The dry process without much abnormal heat, to 

 which the production of steam coal and W^igan 

 cannel is due. 



;. The wet process with heat, to which may belong 



Vol. XIX.— No. 488 



the production of Scotch cannel and the more 

 dense varieties of bituminous or house coals. 

 4. The wet process without long-continued heat, to 

 which we may assign the formation of ordinary 

 bituminous (house coals) and lignite. 



With respect to the nature of the material from which 

 coal has been originally derived, Mr. Thomas has little 

 or nothing to add to what is commonly stated in popular 

 works on the subject. To dismiss the spore-theory in 

 some six or eight lines, with the assertion that *^ there is 

 httle evidence of a weighty character to confirm this 

 hj'pothesis," is, in the light of existing facts, scarcely just 

 to the researches of Carruthers, Morris, and Huxley. To 

 say that all coal has been derived from lepidodendroid 

 spores would unquestionably be incorrect, but to assert 

 that many coals have been largely derived from such 

 material is undoubtedly trae. This much, we suppose by 

 this time, is conceded by the majority of authorities on 

 the subject : the difference between them is rather as to 

 the proportionate part played by the spores. 



As regards the character of the gas occluded in coal, 

 this depends not merely upon the structure of the coal, 

 but upon the conditions under which its formation has 

 occurred and the depth below the surface at which it is 

 situated. On the whole Mr. Thomas's analjlical results 

 agree fairly well with those of Dr. Meyer, in spite of the 

 somewhat faulty method adopted by the latter ; but the 

 inferences which the two experimenters draw from their 

 observations are not unfrequently opposed. There seems 

 to be a decided difference between the gas inclosed in 

 lignites and that found in coals of the older formations' 

 Zitowitsch first detected carbonic oxide in some speci- 

 mens of Bohemian lignites, and the author has detected 

 the same'gas in appreciable quantity in the well-knowTi 

 lignites of Bovey Heathfield, in Devonshire. On the 

 other hand, no coal of the carboniferous period has been 

 found to contain this gas. Another characteristic differ- 

 ence between the coals of the carboniferous and tertiary 

 periods is seen in the absence of all hydrocarbons among 

 the gases occluded in the latter varieties. 



The presence of carbonic oxide in "after-damp" has 

 been frequently surmised, but Mr. Thomas brings direct 

 evidence to prove the fact. Until quite recently it was 

 the general belief among chemists that when marsh-gas^— 

 the '•' fire-damp " of the miners — is mixed with less air 

 than is required for complete combustion, only as much 

 of the hydrocarbon is burnt as the oxygen present can 

 convert into carbon^dioxide and water. It is now found 

 that when marsh-gas is exploded with a quantity of 

 oxygen or air insufficient for complete combustion, the 

 whole of the marsh-gas disappears into carbonic oxide, 

 carbon dioxide, water, and free hydrogen. The importance 

 of this observation is obvious. It has not unfrequently 

 happened that after an explosion the expressions of the 

 countenances of the victims, who have been found sitting 

 or leaning in the most natural positions, have worn no 

 trace of fear or intense anxiety, such as we should sup- 

 pose would come upon them amidst the roar and wTeck of 

 the disaster. These men have not been asphyxiated by 

 carbonic acid or drowned in excess of nitrogen : they 

 have been struck down by the infinitely more deadly car- 

 bonic oxide. Instances too have occurred in which the 

 explorers after an explosion have been ahnost as suddenly 



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