304 Strictures on Professor Backlamfs Inaugural Lecture. [Nov. 1, 
matter, combined with sand or argil, 
and the humour of the calcareous spar, 
we may, without extravagance, accord 
the power of almost instantaneous for¬ 
mation ; and we even know, by the ex¬ 
perience of latter chemists, these trans¬ 
formations have been by them effected.* 
And I trust, from the integral molecule 
of the smallest crystal of this spar to 
the mass of a mountain range, it is 
probable the whole obeyed one law, 
and that the strata of limestone hills 
are only the effects of original fracture 
and decay, as we trace the same appear¬ 
ances in weather-beaten specimens of 
large crystals externally attached to 
them. 
Of the inclined order , including shale 
or slate, and grit and sandstone. We 
see also that rhombic forms (produced 
by the laminae whose laws of deposition 
are stratific and terminations angular) 
are evident on careful inspection, and 
in rhombic-slate, so called from its de¬ 
cided analogy to calcareous rhombic 
spar, quite decided. We can see they 
are limited to a certain angle in their 
opposite lines of deposition. The coal 
measures also have all, though less 
apparent, a luminous conformation, 
whether in the pennant, composed of 
sand, and particles of carbon or shaly, 
or of trap texture, and the coal itself is 
in all great beds luminous, and only 
with a fracture that shews it had crys¬ 
tallized under great pressure—yet still 
the law is simple; a dual motion, in¬ 
variable throughout, tending each way 
to what, at its formation, was probably 
the centre of gravity towards the ori¬ 
ginal nucleus of the earth. 
Of the third class , or secondary roclcs , 
as some have denominated them, that 
are termed horizontal, who has any 
doubt that dyes, whether blue or white, 
have been constructed by the crystali- 
zation of the shelly or sparry matter 
it had absorbed in a state of muddy 
deposition ? Sfunsfield slate is of the 
same contexture and operation as v ell 
as forest marble. We can discover 
tile crystals in our own red sand stone 
in the canal (first pointed out to me by 
my friend Dr. Fox) enormous they are, 
but distinct for so coarse a erystaliza- 
fion, and no doubt fullers-eartli has 
been united by some weak effect of this 
sort of disposition to obey the general 
law. 
Rock-salt is indisputably thus formed 
and its fracture, both ways, evidently 
* See Mr. Hatchet’s experiments. 
luminous like the calcareous spar; and 
although the oolites but partially admit 
of our viewing them in the form of even 
decomposed crystals, still less the corn- 
brash. They have doubtless been de¬ 
tached from a like formation; and in 
the mode in which chalk has deprived 
silex of the power to assume the crys¬ 
talline form in its beds. We see, in my 
humble opinion, that flint is only quartz 
neutralized by chalk, if I may be allow¬ 
ed the expression; for when passing 
the globule of chalk, they find their 
way into the cavernous parts of the 
flint, caused by the expansion of air ; 
they then line the surface with regular 
hexhedral crystals, just as quartz or 
pure silex does when after inSltration 
it escapes from ocherous clay or lime¬ 
stone, and. forms itself freely and spon¬ 
taneously in its cavities; as we witness 
continually in the potatoe stone of 
King’s Weston, the origin of which 
doubtless were babbles in the mass of 
sand stone that lines the coast, whose 
hollows, giving free vent to the infil¬ 
trating quartous humour with which it 
was saturated, thereby occasioned a 
silecious rind, as it were, to be formed 
round these cavities, some of which are 
more solidified than others, and thence 
resemble agates when fractured, espe¬ 
cially when they have been accompa¬ 
nied by calces of iron, as in those of 
Barring!on Coombe, near Langford, in 
Somersetshire; and these, where the 
coast is beaten down by winter storms, 
being infinitely harder than the sand 
stone, their matrix, as the pieces are 
rolled, become detached from it, and 
remain on the beach like hollow balls, 
where they acquire sometimes a smooth 
surface, as polished as boldered pebbles, 
resembling much in form the potatoe, 
whence its name. But to return from 
this digression, we may. I think, affirm 
that, except in the divisions of marie 
and clays found in the intervals of 
limestone, in some places, and which 
doubtless were the result of repulsive 
argillaceous matter, placed out of the 
influence of all the cementary bodies, 
for the purpose of dispersing or detain¬ 
ing the springs that flow from the sur¬ 
face through the flaws of limestone 
hills, (so that no where that necessary 
element, the vital principle of the earth, 
should be wanting) all other substances 
seem to he the work decidedly of crys¬ 
tallization, acting by one general laic , 
compression at opposite points , or the 
attraction of opposite poles universally ; 
but how, is as unknown to us as the 
principles 
