SECTION IV., 1910. [ 23 ] Trans. R. S. C. 
IIl.—The Formation of Coal. 
By D. B. Dowtina. 
(Communicated by L. M. LAMBE and read 27th September, 1910.) 
The materials from which coals are supposed to have been derived 
are the remains of former living organisms. Among the lower grade 
coals, such as the lignites, some are found to be so manifestly made up 
of woody fibre that their derivation from decayed vegetable matter is 
without doubt. In the more altered coals evidence of the same origin 
is given in microscopic fragments of cellular matter and plant spores. 
There are however certain coals sometimes in seams or portions of seams 
that show apparently no organic structure or have strongly marked 
bituminous characters which have suggested a possible enrichment from 
petroleum deposits. If we assume that the bituminous characters are 
derived from the decay of plant or animal life we need only enquire into 
the possible method of decay and subsequent alteration. In this we 
are already assured that bitumen in many cases has been proven to have 
originated from the decay of plant and animal life. If the bitumen or 
bituminous characters of coals are assumed to have originated from 
petroleum deposits deeper seated than the coals then the method of 
impregnation must be considered—a matter that is much harder to 
‘account for. 
In considering the question of the derivation of the various kinds 
of coal from a common origin, an enquiry into the composition of the 
several varieties is necessary. The general alteration toward coal is 
accepted as an increase in the carbon content; but at each degree of 
alteration there are variations in character among the different deposits. 
These variations are almost entirely due to variations in the hydrogen 
percentages. The behaviour of coals having hydrogen above the normal 
will be—free-burning, bright flame, coking, or that generally described 
as due to fatty characters, while those with hydrogen below the normal 
will be short flame, non-coking and be generally what is described as 
dry coals. 
The question then of the derivation of the different varieties of 
oal from a somewhat uniform constituent, namely woody fibre, involves 
the consideration of the possibilities, in the different stages of alteration, 
for the preservation or the loss of the hydrogen of the original material. 
As comparatively little has been written on this part of the subject the 
present paper aims at a presentation of some possible conditions that 
may have had an influence on the variations that are found in the final 
product. 
