CRYSTALL 
cnce in feparate homogeneous mafles, in oppofition to 
the tote of accidental and heterogeneous mixture. 
They likevvife owe to it their regular crytoTline forms ; 
and without this law, the folid parts of our globe would 
only have been a confufed chaotic mafs. To the latter 
we are indebted for the great variety of compound 
bodies which are the refult of fo few elementary fub- 
tonces, and likevvife for the changes that take place 
amongft them ; even the procelfes performed in the la¬ 
boratory of the chemift are founded on this. 
Bodies that are folid have their aCtive powers centred 
in themfelves, and eternal repofe is the refult; unlefs 
another body, in confequence of the attraction of com¬ 
bination, unites with them, wheiva new body is formed. 
But all bodies in a fluid tote are combined with their 
folvent, and then their particles, thus feparated, have 
little tendency to unite with each other. But as foon as 
this folvent is withdrawn, the particles that compofed 
the Ample folid body again unite ; and they unite ac¬ 
cording to particular laws; fo that, under proper cir- 
cumtonces, they form regular polyhedral figures invaria¬ 
bly the fame. If feveral are mixed in the fame folvent, 
they in becoming folid do not unite indifferently, and 
without feleCtion, and thus form a heterogeneous mixture; 
though this would certainly be the cafe, did the great 
law of attraction, by which great mafles are governed, 
prevail, where attraction is in the reverfe ratio of the 
fquares of their diftances; but each unites exclunvely 
with its own kind : and the confequence of this is, that, 
inftead of a tumultuous chaotic mixture, beautiful cry- 
ftals are formed, each kind having its own proper cha¬ 
racter. To the law of aggregate attraction then, we 
are indebted for every thing that is homogeneous and 
fymmetric in the fofiil kingdom. Though a very fmall 
part of our earth appears to be compofed of regular 
cryftalline bodies, yet all fubftances that have a Iparry 
or fpathous texture, are nothing but a more or lels tu¬ 
multuous aflemblage of indeterminate and half-formed 
cryltals. As far as our fight, even aided by the micro- 
fcope, will extend, we fee that the firft rudiment of a 
crytol is its perfeCt form ; that in this its embryo ftate, 
if we may ufe the expreflion, it differs only in fize from 
what it will be hereafter. It is eafy to conceive, that 
many minerals which have not regular forms, may never- 
thelefs be the refult of cryftallization ; and that we may 
go by degrees from the mod perfeCt geometric figure, 
to the mod tumultuous aflemblage of crydalline parti¬ 
cles. In the fenfe in which the word crydallization is 
here ufed, every concretion from a fluid date is the refult 
of crydallization, and may exid either in the date of 
regular crydals, or be fo irregular as not to be definable, 
or in the date of confufed aggregated particles. Thefe 
three different dates, it is not neceflary to obferve, run 
into one another. It is in this latter date that many of 
the minerals that form entire mountains are found; pro¬ 
bably all, except thofe which are formed of the powder, 
dud, or fragments, of other rocks, as the breccias, fand- 
flones, &c. yet even thefe are but the ruins of thofe 
which had been formed in this manner. It is, then, to 
this law we owe every thing that is crydalline, fym¬ 
metric, and homogeneous. 
However important the law we have juft treated of 
may be in the formation of fofllls, it mud be clear, upon 
an attentive confideration of its characters, that it can 
only be the caufe of the aggregation and concretion of 
the elementary fubftances; that thought brought thefe 
out of their ■chaotic confufion into beautiful homoge¬ 
neous mafles, and regular fymmetry ; yet it never could 
combine them, and in various proportions; and thus 
create, from fo few elementary principles, fuch a multi¬ 
plicity of forms as are the refult of thefe combinations. 
This is dependent on a quite different law, the law of at - 
tradion of combination. 
As the fcience of chemiftry is little more than the 
knowledge of the preferring or feleCting difpolition «f 
Vol, V. No. 284, 
OGRAPH Y. 425 
the different elementary fubftances and their compounds, 
and its operations little more than the adjufting and 
difpofing them to reciprocal aftion, every page of che- 
miftry 1 mud bear witnefs to the exiftence of this law. 
It has this conformity with the lad kind of attraction, and 
this difference with the attraction of great niaires, that it 
onlyaCtswhen the bodies are almoft or altogether in contact. 
Though this law merely concerns matter of different 
kinds, there is no univerfal rule that there fhould be a 
combination between any two of them indifferently; 
for, on the contrary, there are fome that never will com¬ 
bine together. A great difficulty here arifes relative to 
mixture and combination, which though perfectly dif¬ 
ferent in their natures, are fometimes not to be didin- 
guilhed. There can be no doubt, but that the principal 
components of hard pellucid crydalline bodies are in a 
ftate of combination; but likewife there can be no 
doubt, that often adventitious matter is enveloped in 
their mafles, with which they are only mixt. For we 
know by experience, that in many cafes circumftances 
are fuch, that the cryftalline matter is not able to reject 
the heterogeneous, but envelops it in its fubftance. 
This is often obfqrved in rock cryftal, in which chlorite 
earth, aCtinolite, afbeftus, See. are found ; and fome¬ 
times the former are fo intimately mixed with it, and in 
fuch quantities, that the folfilift is inclined to refer it to 
a different genus. In the cryftallized fand-ftone of Fon¬ 
tainebleau, though the calcareous fpar is mixed with 
twice its own quantity of fand, yet it affumes its ufual 
cryftalline form. 
If it be then difficult in regular cryftalline bodies to 
know which of their components is combined, and 
which only mixt; how much greater mud the difficultv 
be to afcertaln this in the great rocks, the refult of con¬ 
fufed crydallization ! In thefe, it is clear, if we reflect 
on what mud have pafled on their concretion, that no¬ 
thing heterogeneouscould have been rejected and thrown 
afide as in the formation of regular crydals, but that 
every thing mixed in the fluid mafs mud have been in- 
veloped, and mud now conftitute a part. A means of 
afeertaining this may occur to fome philofophers; and 
probably it may be this : that thofe components which 
are only mixed and not combined, may be readily ex¬ 
tracted by certain reaCtives, which will not affeCt them 
if they aie in a ftate of combination. But this, though 
true in theory, would be difficultly put in practice. 
Some readers may probably afk, how thefe elementary 
fubftances can have been combined, and how they have 
cryftallized, fince neither the components hor the com. 
pounds are foluble in water. This queftion, we believe, 
has never been anfwered; and it has given rife to, or 
fupported, the opinion, that fire has been the agent in 
thefe procefles. Yet difficulties, at lead equally great, 
will be found in this hypothefis, which it would be im¬ 
proper, on account of the extent of the neceflary dif- 
cuffion, to ftate. That there can be no doubt that there 
was a time, when the prelent great mafles and beds of 
rock were not in exiftence, when the elementary fub¬ 
ftances of which they are compofed were free and un¬ 
combined ; that thefe elementary fubftances were more 
Ample than what we confider fuch at this day; which 
moft chemifts, though they have no hypothefis to fup- 
port, are inclined to think are formed of ftill more 
Ample elements. If this be granted, it may then be 
eafily conceived that they were in a ftate of folution ia 
water, notwithftanding our prefent elementary fub. 
ftances, the refult of their combination, are infoluble in 
this fluid; juft in the fame manner as the very foluble 
bodies, the tartarous acid, and the vegetable alkali, 
form by their union an almoft infoluble compound. I 
fhould always be recollected, that there is now no pro» 
cefs going on in nature fimilar to that by which our 
rocks and ftrata were formed. 
As this fubjeCt is fo intimately connected with Mine¬ 
ralogy, and as engravings of the different genera of 
S fyar»> 
