60 Structure of a peculiar Combustible Mineral, 
or three distinguishing characteristics, first the woody fibre, the scalariform 
tissue, and the cellular tissue. 
Is this upon the examination of a great many sections ? — Yes. That 
was generally, not mere accidental structure of particular pieces. 
You saw a drawing made by Dr. Greville? — I was present when that 
drawing was made. 
And that gave a sufficiently distinct idea of the course of examination ? 
— Yes. 
Of the Torbanehill and some other coals ? — Yes ; and the Lesmahagow, 
Kinneil, Capeldrae, and some other cannels. 
I believe the drawing was made from a section furnished by you ? — 
That is a most beautiful specimen of cellular tissue. 
This is the most beautiful specimen you have seen of woody fibre ? — I 
distinguish woody fibre from cellular on account of the more regular 
formation of the cells. 
You have no doubt that this is a vegetable p»roduct ? — Not the least. 
[Witness was shown the drawings illustrative of cellular tissue and 
woody fibre, and distinguished each with great precision.] 
You know what shales are ? — Yes. 
Do shales ever exhibit vegetable structure? — As shales they do not. 
How would you describe a shale ? — There are several forms of shales. 
Supposing the coal to be so mixed with earthy matter as to be incapable 
of being used for fuel, then that would be called a coaly shale. 
And when the coaly matter is so great in proportion to the earthy mat- 
ter that it will burn ? — I should consider this a coal. 
And more or less pure according to the admixture of earthy matter ? — 
All coals contain more or less of earthy matter, and accordingly the coals 
run into shales as the earthy matter increases. 
When you come to a substance beyond which a substance will not 
burn, you would call it a coaly shale ? — Yes. 
It is very difficult to draw the line at the exact place ? — Very difficult. 
Has this mineral anything of the character of a shale? — Not the least, 
so far as I have been able to detect. 
You have seen specim.ens of Methil coal, and examined them with the 
microscope ? — Yes. 
And did you find anything to distinguish the Boghead mineral ? — 
So far as external appearance went, I could scarcely distinguish the one 
from the other, and there was also a great similarity in internal structure. 
There are a variety of cannels which approach each other very closely ? 
— In regard to the distinction between the two there is not a more com- 
mon one than this, the capability of burning and being used for the 
purposes of fuel. 
If the substance would burn, and could be used as fuel, you would say 
it Avas a coal ? — Yes, I would. 
If any substance is sold in the market as a coal, is it a coal ? — Yes, I 
should think so. 
There is no science against this ? — None that I am aware of. 
Cross-examined hy the Dean of Faculty, — I suppose whatever comes out 
of the coal measures and burns by itself is coal ? — No ; I would not say 
that. You might get a fragment of bitumen, which would not be coal, 
and that burns by itself. 
Is that the only exception ? — I am not prepared to say that there are 
any other exceptions. 
Fragments of bitumen would be an exception ? — Yes. 
The way by which you distinguish a coal from a shale, or a shale from 
