Discussion on Coal. 517 
preceding speaker regarding the supreme importance of the closest 
co-operation between chemical and microscopical investigators of 
coal-substance, and of both with the work of the field-geologist, if 
we are to ensure the most intelligent and profitable use of our coal 
resources. The great importance of the problems involved no one 
would question, and the experience he had had in their investigation 
had convinced him that only a considerable body of workers dealing 
in close co-operation with all branches of the subject could hope to 
attain in reasonable time to the endsdesired. Hestrongly hoped that 
this discussion might have such anissue. In one particular he desired 
to differ slightly from Dr. Stopes; while all agreed that every true 
coal was a mass of more or less decomposed vegetable material, he 
was inclined to suspect that, in general, it was the amount and 
character of the decomposition which determined the quality of the 
coal, rather than the nature of the original plants. Certainly it 
would be unwise to assume that any very intimate relationship must 
exist between the original composition of a given plant-structure, 
and the composition of the coal-substance into which that structure 
is now converted. Palzobotanists would remember that the most 
beautifully preserved plant-tissues consisted almost wholly of calcium 
carbonate or silica, and similarly in coal itself the original constituents 
of the cell-walls, etc., may be very extensively replaced by other 
materials, though the materials in this case are the decomposition 
products of the plants themselves. He regarded the co-operation of 
various classes of workers as especially necessary in discriminating 
the highly complex association of varied materials which entered into 
the composition of every coal-seam. The field-geologist readily 
recognized the sharply defined and distinguished ‘ bright’ and ‘dull’ 
bands or lenticles of the seam, while the microscopist was able to 
confirm the important differences between them. But the microscope 
enabled us to go much further, and to recognize that two samples of 
‘bright’ coal, indistinguishable in the hand-specimen, are nevertheless 
widely different in minute constitution. The chemist, on the other 
hand, so far as any attempt at all had been made in the rational 
selection of material for analysis, had been in the habit of preparing 
a carefully mixed sample of all parts of the seam to be investigated. 
The analysis of such a sample, while possessing a certain commercial 
value, was clearly of the smallest possible value as a clue to the real 
constitution of any of the varied substances which are grouped 
together as coal. He was convinced that a scientific understanding 
of coals, the obvious pre-requisite of their best utilization, could only 
be attained by the investigation separately of the many distinct 
elements of seams which the eye and the microscope revealed. 
Professor Fearnsides expressed the hope that out of the present 
discussion would come a recognition by chemists that ultimate analyses 
of coals are required for purposes other than the mere determination 
of the equitable selling price of the coal by the truck. He dealt with 
the subject of coal as a rock genus, within which quite a number of 
essentially different species have already been distinguished by 
geologists and others, and asked that chemists should undertake to 
express these known differences in terms of the chemical constitution 
