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YL— THE MICROSTRUCTURE OF COAL FROM AN 
INDUSTRIAL STANDPOINT. 
By A. L. Booth, A.I.C. 
(Messrs. Armstrong, Whitworth & Co., Ltd.). 
(Bead February 15, 1922.) 
Two Plates. 
It is now almost one hundred years since the microscope was 
first used to examine thin sections of coal. Early papers show 
that Witham used the microscope for this purpose in 1832 to 1833, 
and that he was closely followed by Hutton and Lindley. Quite 
an appreciable number of papers dealing with the microscopy of 
coal were published in this country and abroad, during the succeed- 
ing forty or fifty years. Then followed a period when interest in 
the matter lay dormant, but during the last twenty years a revival 
has taken place, and a very promising field of work seems to be 
opening up. Stopes and Wheeler, at the end of a “ Monograph on 
the Constitution of Coal,” published in 1918, give an excellent 
bibliography of the published work from 1832 to date. 
Most of this work deals, however, with the constituents of the 
coal substance, or with theoretical considerations which attempt 
to account for the formation of coal ; but as yet^ little work appears 
to have been done on the use of the microscope in fuel selection 
from an industrial point of view. 
The worker in an industrial laboratory has two important 
considerations to keep always in mind. First, the works must 
be kept running. (This applies generally, but with particular 
force to a fuel laboratory.) Secondly, the works must be run as 
economically as possible, and no matter how empirical or com- 
parative the methods of work may be, if they help towards better 
and more economical working they justify themselves. 
This applies in the case of ordinary chemical analysis of coal, 
and it may even be said of the use of the microscope in metal- 
lography. But though ordinary chemical analysis as applied to 
coal may justify itself, I would like first of all to point out its 
limitations — why it so often fails to give essential information — 
and then to show you the part the microscope can play in fuel 
selection. 
The usual method of examining coal is to make a “ proximate 
analysis.” It has to be carried out under standardized conditions 
