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Transactions of the Society. 
of temperature, and with a standardized type of apparatus, to be 
at all comparative. The analysis usually consists of the determina- 
tion of moisture, and on the dried sample, of the ash, the volatile 
matter and sulphur ; a standardized coking test may also be made. 
The proximate analysis does not give very much information 
unless the type of coal is known, even when carried out under 
these conditions, due allowance being made for the varying ash 
content. A standardized coking test, too, is of doubtful value 
when the ash content is at all high, because a high ash content 
tends to destroy or modify the coking power. 
The “ ultimate analysis ” of coal — that is, the determination of 
the percentage of carbon, hydrogen, oxygen, nitrogen and sulphur — 
on the other hand, has a fair degree of accuracy as its justification, 
and the results have been extensively used for chemical classifica- 
tions. For this purpose the ratio between the carbon and hydrogen 
percentages is generally used. Ultimate analysis, however, is very 
limited in its application. 
I have come to this conclusion, not only from the results of 
experience, but by reasoning from our present-day knowledge of 
coal ; for it is not so much in accordance wdth their ultimate com- 
position that coals vary, but according to the proportion and type 
of substance present in the coal conglomerate. The coal con- 
glomerate is composed of plant remains. The plants then, as 
now, were mainly composed of cellulose, with ligno-cellulose, 
cutoses, and some resins and protein matter. Plant tissues in 
general are, chemically, very much alike ; variations in a species, 
or in the different parts of the same plant, being due mainly to 
various polymerizations and condensations, etc., of the carbo- 
hydrates, so that the ultimate composition of the bulk of plants 
will be very similar. Admitting that this is so, and assuming 
that, in the case of coal, decomposition was fairly uniform, a coal 
would have to be composed, mainly, of some substance which 
differs markedly from the bulk of the plant remains to show r any 
marked difference in its ultimate analysis. The hard or cannel 
coals are a case in point. During coal formation, however, the 
degree of decomposition undergone by the coal substance would 
EXPLANATION OF PLATE VI. 
Numbers. 
1 & 2. — Typical humic coal x 75. Sections cut parallel with and at right angles 
to the bedding plane respectively. 
3 & 4. — Spore coal showing spore exines x 20. Parallel with and at right angles 
to the bedding plane respectively. 
5 & 6. — Hard or cannel coal showing the small round “ yellow bodies ” x 170. 
Parallel with and at right angles to the bedding plane respectively. 
7 & 8. — A good steam-raising coal. Mainly humic, but containing much cuticle 
and spore exines. No. 7 x 20 (parallel with bedding plane). No. 8 
X 170 (at right angles). 
