from the Coal Measures of Torbane-hill. 
43 
into true coal, but having been subjected to a great heat, 
their remains are left as a species of charcoal. Some speci- 
mens of the Torbane-hill coal have a large amount of this 
charcoal upon their upper and under surfaces, and in it, vessels 
of various kinds will occasionally be found, although such 
vessels do not occur in the solid coal itself. 
Examination of the Ash of Coal. — ^Vhe brown ash of coal, 
with the exception of particles, probably of silica, is almost 
wholly composed of vegetable remains, some of which pro- 
perly belong to the coal itself, whilst others are derived from 
extraneous plants which have been mixed up with it. Every 
kind of tissue which has been described as proper to the coal 
may be met with in the ash, when not too much burnt. The 
remains of woody fibres and cells are the most common con- 
stituents, but flat, very opaque, irregular masses, such as are 
shown in Plate V., fig. 4, and which evidently correspond to 
portions of transverse sections of wood, are frequently found. 
Portions of siliceous cuticle, probably of grasses, as shown 
in fig. 6, from a drawing by Dr. Adams, are far from being 
uncommon. In short, when the indications of the woody 
structure of coal are very faint in sections, they are well ex- 
emplified in the ash. Sections of Welsh Anthracite (which 
I believe to be a fossil coke) are most difficult to obtain, and 
when made, afford very unsatisfactory evidence of vegetable 
structure : when, however, the ash is examined, the presence 
of woody tissue is unquestionable. 
The Torbane-hill mineral has been most carefully examined 
by my friend Dr. Adams, and as his investigations were car- 
ried on independently of mine, it will be satisfactory that you 
should be made acquainted with the conclusions he has ar- 
rived at after a laborious series of examinations. They are as 
follow : — 
" The most interesting example which could be adduced, illustrative of 
the differences in essential characters, as demonstrated by the microscope, 
between substances supposed by commercial men to be identical, is found 
in the Torbanehill mineral, known also by the name of Boghead coal. In 
the lawsuit previously alluded to, much of the scientific evidence regard- 
ing this mineral was of a very conflicting character, so much so that the 
court virtually set aside the scientific evidence, and decided on the legal 
merits of the commercial bargain. 
" The importance of the interests involved, and the high character of 
the witnesses examined, have made this trial very celebrated ; and it is 
from an excusable desire that the grounds of the opinion I expressed at 
the trial should be understood, that I now seek to place them on record. 
I will, however, confine my remarks to a very short summary of my 
observations made upon the Torbanehill mineral, leaving a fuller detail 
with my friend, Professor Quekett, who gave joint evidence with me, and 
with whom I have discussed and investigated the whole subject of my 
e 2 
