NA TURE 



209 



THURSDAY, MAY 1, 1913. 



THE CARBONISATION OF COAL. 

 The Carbonisation of Coal. A Scientific Review 



of the Formation, Composition and Destructive 



Distillation of Coal for Gas, Coke and 



By-Products. By Prof. V. B. Lewes. Pp. 



xiv + 315. (London: John Allan and Co., 



1912.) Price js. 6d. net. 

 ^T~*HIS book is a welcome addition to the 

 J_ literature of a subject which is increasing 

 in importance with each successive decade. Prac- 

 tical men are at length beginning- to realise that 

 the utilisation of the store of potential energy in 

 coal by more rational methods than have hitherto 

 prevailed is a problem that has to be grappled with 

 seriously if our supremacy in the chief manu- 

 factured products of the world is to be maintained 

 Authorities of the highest competence have re- 

 peatedly pointed out that enormous economies 

 might be effected if more scientific — that is, more 

 common-sense — methods were employed in the 

 consumption of coal. The waste is universal and 

 extends practically to every industry, although in 

 some to a much greater extent than in others. In 

 the blast furnaces it is relatively small, for the 

 reason that ever since the introduction of the hot- 

 blast, the connection between potential energy and 

 output has received an amount of consideration 

 such as has not been bestowed upon any other 

 aspect of the general problem. On railways, in 

 factories, in brickworks, potteries and glassworks 

 the waste is simply appalling. 



It has been calculated that our annual consump- 

 tion of coal is from 143 to 168 million tons per 

 annum, of which from 30 to 36 million tons are 

 used for domestic purposes. Of this huge amount 

 it is estimated that from 40 to 60 million tons are 

 practically wasted ; that is, this quantity could be 

 saved if gas-generating plant, electric motor and 

 traction, gas heating and gas cooking, briquettes 

 and coke were more generally employed than they 

 are at present. 



We think, therefore, that Prof. Lewes has been 

 amply justified inputting together and in enlarging 

 his Cantor lectures on the carbonisation of 

 coal, given to the Society of Arts in 191 1, and 

 we trust that his appeal to a wider public will 

 meet with the success it undoubtedly merits. The 

 subject, indeed, is admittedly of national import- 

 ance, but the fear is that this country will only 

 waken up to the full significance of that fact when 

 the pinch of necessity has tightened to a real 

 grip — so tight, indeed, that it will be too late to 

 shake it off. 



The purpose of this work is to point out how 

 NO. 2270, VOL. 91] 



the methods known comprehensively as " carbonisa- 

 tion processes " — that is, processes involving the 

 preliminary treatment of coal by heating it under 

 such conditions that initial products are formed 

 capable of being turned to economical account as 

 sources of power — may tend to minimise this waste. 

 To understand fully the rationale of the effect of 

 heat upon coal implies some knowledge of the 

 proximate nature of coal and of the essential differ- 

 ences in composition between one coal and another. 

 On this matter knowledge is confessedly very 

 imperfect, but at the same time a certain amount 

 of information has been gained by the study of 

 the action of various solvents upon coal and by an 

 examination of the nature of the products so ob- 

 tained, as well as of the changes which the coal 

 has experienced by the treatment. Incidentally, 

 Prof. Lewes has been led to speak of the influence 

 of storage, i.e. oxidation, on the nature of coal, 

 and its effect on its coking properties and on the 

 products of its destructive distillation. He is 

 naturally induced to treat of the causes of the 

 spontaneous ignition of coal, and he points out 

 that the phenomenon is certainly more complicated 

 than is generally supposed, and is not wholly, or 

 in all cases, due to the occurrence of "brasses," 

 or any readily oxidisable form of finely divided 

 iron sulphide, but is connected with the character 

 of its proximate constituents. 



A special chapter is devoted to the question of 

 the classification of the various kinds of coal. 

 Strictly speaking, the most rational method would 

 be one dependent upon proximate composition, 

 and perhaps in time to come we may arrive at such 

 a system. At present our knowledge on this 

 matter is far too partial and imperfect to warrant 

 even the attempt, and accordingly we have to con- 

 tent ourselves with the admittedly empirical and 

 irrational systems which the metallurgists have 

 de\ ir>ed for us. Of coutse, in practice, the systems 

 we owe to Fleck, Gruner, Sevier and others — 

 mainly German and Austrian writers — have a cer- 

 tain measure of convenience, and ■ are probably 

 remotely based upon intrinsic differences of 

 chemical nature, but the correlation has not been 

 definitely traced, and is certainly not capable of 

 being stated with precision. 



The greater part of the rest of the work is 

 concerned with the effect of heat upon coal, or, 

 to speak more precisely, on its behaviour during 

 the process of destructive distillation. Of course, 

 this is a very wide subject, and has been treated 

 at great length in many standard treatises. 

 It has, however, not been Prof. Lewes's object 

 to traverse well-trodden ground. His purpose has 

 been rather to direct attention to novel points, or 

 ' to offer his testimony on disputed matters. This 



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