396 TRANSACTIONS OF SECTION C. 



divided into ' cellulosic ' and ' resinic ' types. Each constituent tissue might be 

 supposed to have given rise to characteristic decomposition-products in the coai ; 

 and, in conjunction vtfith Dr. R. V. Wheeler, she was now engaged in testing this 

 point. Such tissues as spore-walls and cuticles proved insoluble in pyridine, 

 and could thus be separated and separately analysed. It was hoped to track 

 down the characteristic products of other tissues in a similar way. Co-operation 

 between the chemist and palaeobotanist was clearly essential. 



Dr. HiCKLiNG desired to support all that Dr. Stopes had said regarding the 

 importance of microscopic study as a guide in the interpretation of the chemistry 

 and geology of coal. He wished only to question the necessity of any very close 

 connection between the chemical constitution of the vegetable ' tissues ' now 

 distinguishable in coal and that of the original tissue of the living .plant. It 

 seemed probable that very extensive substitution of material might have 

 occurred, and that the present character of the coal might be dependent more 

 largely on the extent and character of the ' decomposition ' processes than on 

 the original coniposition of the tissues involved. 



Professor Fearnside.s dealt with coal as a rock-genus, within which a number 

 of essentially different species have already been recognised, and asked that 

 chemists should express these specific differences in terms of chemical constitu- 

 tion. He suggested that the methods of etching used by metallographers might 

 be applied to the study of polished surfaces or cleat surfaces of coal. It was 

 to be desired that the same blocks of coal analysed by the chemist should be 

 studied by the palreobotanist, and that the geologist and mine-worker should 

 combine in choosing samples worthy of investigation. In particular, co-opera- 

 tion between chemists and geologists was to be desired to secure a knowledge 

 of the lateral variations in composition within the individual lenticles of coal 

 which in sum constitute the coal-seam. 



Professor Boyd Dawkins wished to emphasise the probability that the 

 original substance of the plant-tissues whose remains are seen in coal may have 

 been largely replaced by other materials. He quoted examples of such replace- 

 ment in fossils of all types, showing that replacement is the rule and not the 

 exception. Some indication of the organic form of the fossil may even be 

 imparted to the mineral matter which may be deposited around or within it. 

 In his opinion, the greater part, if not the whole, of the organic element in the 

 coal had been subjected to mineral change. 



Professor W. S. Boulton (who presided) expressed his gratification at the 

 opportunity for an interchange of ideas among chemists and geologists upon a 

 subject of vital importance to the* nation. Already much valuable research 

 upon the nature and composition of coal had been done, both on the analytical 

 and on the microscopical and palseobotanical side. He felt sure that when the 

 printed records of the discussion were published they would serve to stimulate 

 fresh and more vigorous research, and more especially to co-ordinate and 

 mutually assist the work of the chemist and geologist, and so enormously 

 increase the value of our greatest industrial asset. 



The following Papers were then read :— 



1. .4 Method of indicating the Age of Geological Formations on Maps 

 in Black and White. By Dr. J. W. EvANS. 



All Pre-Cambrian rocks are represented by shading having a N.W. and 

 S.E. trend; the older Palaeozoic by shading with a N.E. and S.W. trend; the 

 younger Palteozoic by N. and S. shading, and the INIesozoie by E. and W. 

 shading. The earlier metamorphic Pre-Cambrian is indicated by continuous 

 lines, the later metamorphic by broken lines having the intervals 'in adjoining 

 lines alternating with each other ; and the unmetamorphosed Pre-Cambrian by 

 those ha\'ing the intervals opposite. The Cambrian, Ordovician, and Silurian 

 (older Pah-eozoic) are distinguished in a similar manner, and so are the 



