174 DR BENNETT ON THE STRUCTURE OF THE 
now went over the sections of coal in the rich collection of Mr ALEXANDER Bry- 
son of this city, and subsequently carefully examined the numerous sections made 
by Dr Apams of Glasgow. Before the trial of GiLLuspiE versus RusseL came on, 
Dr ApAms, Mr Qurexert, and myself, spent nearly an entire day together, exa- 
mining each other’s specimens, and carefully re-investigating the whole subject. 
It was then that the character of the ashes in the various substances we had 
examined was pointed out to me by Dr ApAms, who, in my opinion, is entitled’ 
to the greatest credit for the laborious, skilful, and successful efforts he has made 
in determining the structure of numerous coals, and pointing out the differences 
they exhibited, when compared with the Torbanehill mineral. At this meeting, 
also, we compared the structure of coal with various kinds of recent woods, we 
incinerated the mineral and certain coals, and carefully examined the ashes; 
and there was established, as the result of this conjoined investigation, as well as 
from the independent researches made by Dr Apams in Glasgow, by Mr QuEKETT 
in London, and by myself in Edinburgh, the most perfect accord with regard to 
all the facts which had been elicited during the inquiry. 
At the commencement of the present session, I brought the subject under the no- 
tice of the Physiological Society of this city, who appointed a committee, composed 
of four gentlemen in addition to myself, all of whom had long been accustomed 
to the use of the microscope, and were familiar with vegetable and animal struc- 
tures. Three of these gentlemen, viz., Dr CoppoLp, and Messrs Bartow and Kirk, 
made farther inquiries and researches, which served to elicit additional facts, 
and to demonstrate, in the language of their report, that “the Torbanehill mi- 
neral is widely different from every kind of coal.” Lastly, with a view of meet- 
ing certain theoretical objections which have been advanced, I have carefully 
examined the structure of various kinds of peat, as well as the stems of recent 
ferns and several fossil plants, which have only served to establish the entire ab- 
sence of connection between these substances and the Torbanehill mineral. 
In now endeavouring to place in a condensed form the results of this extended 
investigation before the Society, I propose, in the first place, to describe the facts, 
as they may be easily demonstrated in the field of the microscope: Secondly, to 
deduce from these facts the structural element which distinguishes every kind 
of coal from the Torbanehill mineral, and explain the cause of the differences 
which are recorded in the proceedings of the recent trial: Lastly, to offer a few 
speculations as to the nature of this mineral, as distinguished from various kinds 
of household and cannel coals. 
I. When we examine a piece of undoubted coal, such as of the Zetland or Buc- 
cleuch coals, it presents to the naked eye a fibrous structure, and has a black 
shining streak. It has been found difficult to make thin sections of it, as in the 
grinding process it readily crumbles down. But when a tolerably thin slice, made 
