39^ Mr. Hatchett's Observations on the Change 
fact ; but, if it were unsupported by any other, the only inference 
would be, that the schistus was most probably of very recent 
formation, and had been produced under peculiar circumstances. 
I was desirous, therefore, to discover some similar cases, which 
might serve as additional corroborative proofs of the gradual 
alterations by which vegetable bodies become changed, so as at 
length to be regarded as forming part of the mineral kingdom ; 
and, from the reasons which have been stated in the commence- 
ment of this Paper, as well as from a certain similarity in the 
external characters of the substance composing the leaves above- 
mentioned with those of the Bovey coal, I was induced to make 
this last also a subject of chemical inquiry. 
In the Philosophical Transactions for the year 1760,* some 
remarks on the Bovey coal, and an account of the strata, are 
stated, in a letter from the Rev. Dr. Milles to the Earl of 
Macclesfield. The object, indeed, of the author, was to esta- 
blish that this and similar substances are not of vegetable, but 
of mineral origin ; and, to prove this, he adduces a great number 
of cases, most of which, however, in the present state of natural 
history and of chemistry, must be regarded as proving the 
contrary ; whilst others, mentioned by him, such as the Kim- 
meridge or Kimendge coal, are nothing more than bituminous 
slates, and of course are of a very different nature. 
Dr. Milles’s account of the varieties of the Bovey coal, and 
of the state of the pits at that time, appears to be very accurate ; 
and, for the present state, or at least such as it was in 1 796, I 
shall beg leave to refer to a Paper of mine, published in the 
fourth volume of the Transactions of the Linnean Society ;-f 
• Vol. LI. p. 534. f Observations on bituminous Substances, p. 138. 
See also Parkinson’s Organic Remains of a former World, Vol. I. p. 126. 
