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foreign element, (foreign, I mean, so far as the general mass 
of the coal is concerned) which has resisted decay better than 
the mass of vegetation which has formed the deposit. Second, 
when coal is treated with nitric acid dense fumes come off, 
this implies that something is undergoing destruction, and the 
importance of the loss is only known when we obtain microscopie 
sections. Sir Wizti1am Dawson has, however, figured* well 
preserved portions of tissue, obtained by the nitric acid 
process; but whether all can be regarded as the tissue of 
the coal-forming plant is, I think, uncertain. Sir Witiiam 
Dawson, with his usual candour, admits that two difficulties 
have impeded his investigations, “and have in some degree 
prevented the attainment of reliable results.” ‘One of these,” 
he says, “is the intractable character of the material as a 
microscopic object; the other the want of sufficient informa- 
tion with regard to the structure of the plants known 
by impressions of their external forms in the beds of the coal 
formation.” Then as to Mr Carrutuers. In my opinion the 
evidence on which he relies can only be regarded in the light 
of circumstantial evidence, and by no means clearly proves 
what Mr Carrutuers claims for it. Take, for instance, a 
modern peat bog. The vegetation which has mainly contributed 
to it are the bog-mosses (Sphagnacee.) Growing in the bog, 
however, are to be found conifers and other vegetation. Suppose 
such a bog to be submerged, as bogs sometimes are, what would 
be the result? The vegetable mass would undergo decay, it 
would pass from peat to lignite, and thence to coal. If it 
were worked in the distant future, the Geologists and miners 
of the period would doubtless find the remains of conifers and 
of other vegetation, but if the deduction were drawn that, 
because these remains could be recognised, that therefore the 
coal originated from that form of vegetable growth, then a 
very wrong idea would be gathered as to the main origin of the 
mineral. I may add that it is by no means improbable that 
coal seams may not have originated in some such manner as 
peat. 
* Acadian Geology, 3rd Edition, p. 464. 
