512 Notices of Memoirs—British Association— 
wanted an agreed classification of coals based on both physical and 
chemical characters. He asked help from the chemists in providing 
such a classification, with a clear definition of each variety. The 
value of the analyses provided by the chemists would be greatly 
enhanced, from the geological point of view, 1f they could be informed 
of the nature of roof and floor respectively, since both are factors 
which undoubtedly influence the composition and properties of the 
coal between them. It was also very desirable that the analyses 
should be presented somewhat more uniformly drawn up than is the 
case at present. For geological purposes an ultimate analysis is of 
little or no use alone, but should be given together with one of the 
ordinary commercial kind, in which the percentage of free carbon, 
volatile matter, and ash is shown. One seam in the Newcastle Coal- 
field yielded in the north the best household coal, in the centre of its 
area the best coking coal, and, further south, the best steam coal of 
the district. He concluded by saying that after fifty years of work 
at coal he knew less what it really was than he thought he knew 
at first. 
Professor W. A. Bone said he found it difficult to make any very 
definite statement about the chemical nature of coal, of which we 
were still largely ignorant. The technical chemist was in the habit 
of making certain tests with a view to judging the suitability of a 
given coal for particular economic purposes, and the ultimate com- 
position of the coal substance can be determined with considerable 
accuracy. But such data, however useful as a guide to the user of 
coal, gave little or no information as to the chemical structure of coal. 
Within recent years a good deal of work had been done upon the 
action of various organic solvents, notably pyridine, upon coal, upon 
the results of which certain tentative conclusions had been drawn as 
to two different types of constituents (sometimes termed the 
‘resinous’ and ‘cellulosic or humic’ types respectively) which are 
supposed to make up the coal substance, and this seemed to be a 
promising line of attack upon the problem. But it was too soon yet 
to put forward anything more certain than a working hypothesis. 
During the past thirty years a number of eminent chemists had 
individually attacked the problem of the chemical structure of coal 
on different lines, but little or nothing had been done to co-ordinate 
these various researches or to review their results in any active 
manner. In his opinion no great progress was likely to be made 
except on the lines of some well-considered scheme of research in 
which the various workers would find their place and collaborate. 
The Fuel Economy Committee had the matter in hand, and if the 
geologists wished to be more largely represented their further valued 
assistance would be welcomed by the chemists. _ 
Professor Kendall (Leeds University) addressed himself particularly 
to the question of the nature and origin of the ash in coal-seams, 
asubject of great economic and geologicalimportance. He recognized 
three sources of the mineral substances found in coal-seams—first, 
the residue of the actual mineral constituents of the plants composing 
the coal; second, detrital mineral matter, generally fine dust or mud, 
that had been blown or washed into the area of coal-formation; and 
