414 C11Y 
another more than they are drawn by the fluid, then 
will they run into cry dais. And this is peculiar to 
thofe, that, let them be ever fo much divided and re¬ 
duced into minute articles, yet, when they are formed 
into cryftals, they each of them realTume their proper 
fliapes ; fo that one might as ealily dived them of their 
faltnefs, as of their figure. This being an immutable 
and perpetual law, by knowing the figure of the cryf¬ 
tals, we may underltand what the texture of the par¬ 
ticles ought to be, which can form thofe crydals ; and, 
on the other hand, by knowing the texture of the par¬ 
ticles, may be determined the figure of the cryftals. 
Quincy. —The mafs formed by congelation or concretion. 
.—All natural metallic and mineral cryjlallizations were 
effected by the water, which firft brought the particles, 
whereof each confifts, out from amongft the matter of 
the ftrata. Woodward. 
To CRYS'TALLIZE, v. a. [from cryjlal.~\ To caufe, 
to congeal, or concrete in cryftals.—If you dilfolve cop¬ 
per in aqua forth or fpirit of nitre, you may, by cryf- 
tallizing the folution, obtain a goodly blue. Boyle. 
To CRYS'TALLIZE, v. n. To coagulate, congeal, 
concrete, or ffioot into cryftals.'—Recent urine will 
ciyjlallize by infpiflation, and afford a fait neither acid 
nor alkaline. Arbuthnot. 
CRYSTALLOGRAPHY, /. [from y.pvrccMoe, of 
5tgt>o;, cold, and ctteAAw, to contract or freeze; and ;\oyo,-, 
a dodtrine or difcourfe. ] That fcience which inveliigates 
the principles of cryftallization, or the a£t by which un¬ 
organized bodies affume fpecific forms. Hence, as cryf¬ 
tallization is nothing elfe than the conftant arrangement 
of the particles of matter into fome given form, fo it is 
evident that before this operation can take plqce, the 
particles of the body to be cryftallized mult be at fome 
diftance from each other, and that they mutt be at liberty 
to obey the laws of attraction. They may be put into 
this fituation by three methods, folution, fufpenfion, 
and fufion. 
1. Solution is the common method of cryftallizing 
falts. They are diftolved in water : the water is flowly 
evaporated, the faline particles gradually approach each 
other, combine together, and form fmall cryftals, which 
become conftantly larger by the addition of other parti¬ 
cles, till at luft they fall by their gravity to the bottom 
of the veffel. It ought to be remarked, however, that 
there are two kinds of folution, each of which prefents 
different phenomena of cryftallization. Some falts dif- 
folve in very fmall proportions in cold water, but are 
very foluble in hot water ; that is to fay, water at the 
common temperature has little effect upon them, but 
water combined with caloric difftdves them readily. 
When hot water faturated with any of thefe falts cools, 
•it becomes incapable of holding them in folution : the 
confequence of which is, that the faline particles gradu¬ 
ally approach each other and cryftallize. Sulphat of 
foda is a fait of this kind. To cryftallize fuch falts no¬ 
thing more is neceflary than to faturate hot water with 
them, and fet it by to cool. But were we to attempt to 
cryftallize them by evaporating the hot water, we fhould 
not fucceed; nothing would be procured but a fhapelefs 
mafs. Many of the falts which follow this law of cryf¬ 
tallization combine with a great deal of water; or, which 
is the fame thing, many cryftals formed in this manner 
contain a great deal of water of cryftallization. 
2. It appears, too, that fome fubftances are capable 
of afluming a cryftalline form merely by having their 
particles fufpended in water, without any regular folu¬ 
tion ; at lead it is not eafy, on any other fuppofition, 
to explain the cryftallizations of carbonat of lime fome- 
times depoftted by waters that run over quantities of 
that mineral. 
3. There are many fubftances, however, neither folu- 
ble in water, nor capable of being fo minutely divided 
as to continue long fufpended in that fluid ; and which, 
notwithftanding, are capable of airuming a cryftalline 
It)rm. This is the cafe with the metals, with glafs, and 
CRY 
feveral other bodies. The method employed to cryftal¬ 
lize them is fufion , which is a folution by means of calo¬ 
ric. By this method the particles are feparated from 
one another; and, if the cooling goes on gradually, 
they are at liberty to arrange themfelves in regular 
cryftals. 
The phenomena of cryftallization feem to have at- 
trafted but little of the attention of the ancient phi- 
lofopiiers. Their theory indeed, that the elements of 
bodies poflefs certain regular geometrical figures, may 
have been fuggefted by thefe phenomena ; but we are 
ignorant of their having made any regular attempt to 
explain them. The fchoolmen afcribed the regular fi¬ 
gure of cryftals to their fubftantial forms, without giving 
themfelves much trouble about explaining the meaning 
of the term. This notion was attacked by Boyle; who 
proved, that cryftals were formed by the mere aggre¬ 
gation of particles. But it ftill remained to explain, 
why that aggregation took place ? and why the parti¬ 
cles united in fuch a manner as to form regular figures ? 
Thefe queftions were anfwered by Newton. According 
to him, the aggregation is produced by the attraftion 
which he had proved to exift between the particles of 
all bodies, and which acts as foon as thefe particles are 
brought within a certain diftance of each other by the 
evaporation of the liquid in which they are diffolved. 
The regularity of their figures lie explained by fuppo- 
fing, that while in a ftate of folution they were arranged 
in the liquid in regular rank and file ; the confequence 
of which, as they are adted upon by a power which at 
equal diftances is equal, at unequal diftanccs unequal, 
will be cryftals of determinate figures. This explana¬ 
tion, which is worthy of Newton, is now univerfally ad¬ 
mitted as the true one ; but (till, there remain various 
phenomena relating to cryftallization which it is no eafy 
matter to explain. 
It has been obferved, that thofe falts which cryftallize 
upon cooling, do not affume a cryftalline form fo readily 
if they are allowed to cool in clofe velfels. If a fatura. 
ted folution of fulphat of foda, for inftance, in hot wa¬ 
ter be put into a phial, corked up clofely, and allowed 
to cool without being moved; no cryftals are formed at 
all; but the moment theglals is opened, the fait cryftal- 
lizes with fuch rapidity that the whole of the folution 
in a manner becomes folid. This phenomenon has been 
explained by fuppofing, that there is an affinity between 
the fait and caloric, and that while the caloric continues 
combined with it the fait does not cryftallize; that the 
caloric does not leave the fait fo readily when external 
air is not admitted, as glafs receives it very flowly and 
parts with it very flowly. In fliort, the atmofpherical 
air feems to be the agent employed to carry otf the calo¬ 
ric ; a talk for which it is remarkably well fitted, on 
account of the change of denfity which it undergoes by 
every addition of caloric. This is confirmed by the 
quantity of caloric which always makes its appearance 
during thefe fudden cryftallizations. This explanation 
might be put to the teft of experiment, by putting two 
folutions of fulphat of foda in hot water in two fimilar 
velfels; one of glafs, the other of metal, and both clofed 
in the fame manner. If the fait contained in the metal¬ 
lic veflel cryftallized, which ought to be the cafe on 
account of the great conducting power of metals, while 
that in the glafs veflel remained liquid, this w T ould be a 
confirmation of the theory, amounting almoft to demon- 
ftration. On the contrary, if both folutions remained 
liquid, it would be a proof that the phenomenon was 
ftill incompletely underftood. 
If the regular form of cryftals depends upon the ag¬ 
gregation of particles, and if during all cryftallizations 
this aggregation goes on in the fame manner, why have 
not all cryftals the fame form ? Some have afcribed thefe 
differences to a certain polarity which the particles of 
bodies are fuppofed to poflefs, and which difpofes each 
kind of particles to arrange themfelves according to a 
certain law. Sir Ifaac Newton appears rather to have 
afcribed. 
