(51) 
not fail to excite an interest in the minds of all 
those who possess any taste for productions of this 
sort, and who occasionally indulge themselves in 
the study of Crystalography. 
The Count de Bournon, in his elaborate Treatise 
on the Crystalizations of the Carbonates of Lime, 
has enumerated upwards of Seven Hundred modifi- 
cations, and exemplified them also by numerous 
Plates. Two or Three Hundred modifications, at 
least, ‘may certainly be mentioned, as occurring in 
our Limestone; many of them are beautifully perfect 
and transparent; and are not figured in his book. 
I would enumerate the Rhomboid, the Prism, and 
the Dodecaedron, as the three primitive forms, on 
which, with the elongation of their angles, all the 
other modifications are dependant, and to. which, it 
strikes me, they may be generally referred, or traced 
back: but, these are so multiplied by truncations, 
by bevellings, by their position in their matrix, by 
their union with each other, and also, by other 
accidental circumstances, to which they are continu- 
ally liable, that it is frequently very difficult -to 
