CRY 
CRYS'TAL, f. Icryjlallus , Lat. from y. ? vo(, cold, and 
to contract.] A hard, pellucid, concrete body, of 
fome regular geometrical figure, colourlefs, and of lin¬ 
gular tranfparency. T his is the common acceptation of 
the word ; but it is now ufed in a more enlarged fenfe, in 
chemiftry and mineralogy, to denote thofe portions of 
bodies which have alTumed a fymmetrical form at the 
time of acquiring the folid (late, fuch as cryftals of 
falts, of metals, of earths, and of every other fub- 
ftance that pofleffes a confiderable degree of fimplicity 
in its compolition, whether diaphanous or opaque. For 
the forms of an infinite number of cryftals, fee the articles 
Chemistry, Crystallography, and Mineralogy. 
CRYS'TAL, Fatfitious. A very fine tranfparent 
glafs, made in imitation of precious (tones, fometimes 
called cryftals, but more ulually paftes. Opticians dif- 
tinguilh the denfe white glafs, which contains much 
calx of lead, by the name of cryjlal glafs, and fre¬ 
quently by that of white flint. 
CRYS'TAL, Mineral. In ancient difpenfatories there 
is a formula for making a fait under this name, by fufl¬ 
ing nitre, projecting a little fulphur thereon, and after¬ 
wards calling it into cakes. It is not neceflary to give 
any detail of the,imaginary advantages fuppofed to be 
obtained by treating nitre in this manner. The cryftal 
mineral will vary according to the management. Part 
of the nitrous acid may be decompofed by the heat, 
and part will be decompofed by the detonation. The 
fulphur will be acidified, and will .combine with the 
portion of difengaged alkali. The cryftal mineral will 
therefore confift of nitre contaminated with a fmall 
quantity of vitriolated tartar, and is not worth the 
trouble of making, becaufe pure nitre will anfwer 
every medical purpofe to which this has been ufually 
applied. 
CRYS'TAL, Rock. In mineralogy, the pureft fpe- 
cimen of filiceous earth. This is either colourlefs and 
cryftallized in hexagonal pyramids, and then called 
mountain cryftal, or in various other forms. The moft 
violent heat of a furnace has not been found to dimi- 
nilli the weight or hardnefs of rock cryftal; but pro- 
fefior Errhmann fufed it by flame, urged with a ftream 
of vital air. The formation of rock cryftal has much 
engaged the attention of chemifts. There feerns to be 
little doubt that this earth is fufpended in water, moft 
pirobably by a true folution, and afterwards depofited 
in the fame manner as other foluble bodies are : the 
only peculiarity appears to be, that fo very large a 
quantity of the water is required to fufpend a lmall 
quantity of the earth, that this laft has eluded the at¬ 
tention of philofophers. The effeCts of water in the 
extenfive operations of nature, relative to this earth, are 
very confiderable. The vaft bafin chiefly compofed of 
filiceous materials depofited by the water of the pro¬ 
digious fountain of Geyler, in Iceland, defcribed by 
Vontroil, affords a proof that hot water fufpends fili¬ 
ceous earth ; and points out a feries of experiments to 
be made with Papin’s digeftor, though not yet under¬ 
taken by any one. And the obfervations of Mr. Genf- 
fane, quoted by Chaptal in his Elements of Chemiftry, 
with others of the profeffor himfelf, prove that rock 
cryftal is formed in a way not at all differing from that 
of calcareous fpar. Mr. Genffane (hews that a quartzofe 
gurh is formed by fimple tranfudation upon ferruginous 
rocks; and the fame naturalift has taken notice that when 
the gurh is worn and depofited by w'ater, rock cryftals 
are formed. The waters which work their way through 
the quartzofe rocks of the mine of Chamillat, near Planche 
les Mines in Tranche Compte, form quartzofe ftalaCtites, 
to the roof of the works, and even upon wood. The 
extremities of thefe ftalaCtites, which have not affumed 
a folid confidence, are of a granulated and cryftalline 
fubftance, eafily crufhed between the fingers. In thefe 
cavities, called craques by the miners, a fluid gurh is 
often found, and (till oftener cryftals ready formed. 
Chaptal obferved at Saint Sauveur, in the work of La- 
Vol. V. No. 283, 
CRY - 413 
boiftiere, near Bramebiaou, feveral incruftations ot 
gurh on the fide of the gallery ; and thefe fpreading in¬ 
cruftations were terminated by well-formed cryftaiS, 
wherever the wall overhung, or deviated from the per¬ 
pendicular. This gurh, when handled, and minutely 
examined, had no other appearance than that of a fili¬ 
ceous pafte of confiderable purity. 
Bergman obtained cryftals refembling. rock cryftal, 
but not fo hard, by difiolving filiceous earth in the acid 
of fpar, and leaving it to fpontaneous evaporation. 
Chaptal obferved a faCt of the fame nature. Mr. 
Achard obtained a cryftal as hard and as tranfparent as 
rock cryftal by diffolving the earth of alum in water 
impregnated with fixed air, the fluid filtrating very 
(lowly through the bottom of a porous veffel of baked 
clay. M. de Morveau, having inclofed rock cryftals 
with a bar of iron in a bottle filled with gafeous water, 
perceived a vitreous point fixed to the iron, which he 
fuppofed to be a rock cryftal formed by this operation ; 
fo that he confiders iron as a neceflary intermedium to 
enable the carbonic acid to diffolve quartz. Rock cryf¬ 
tal, though the fofteft among tranfparent (tones, is 
harder than moft of the opake (tones, and much harder 
than glafs. 
CRYS'TAL, adj. Confiding of cryftal: 
Then, Jupiter, thou king of gods, 
Thy cryjlal window ope, look out. Skakcfpeare r 
Bright; clear ; tranfparent ; lucid ; pellucid : 
In groves we live, and lie on molly beds, 
By cryjlal dreams that murmur through the meads. 
Dryden . 
CRYS'TALLTNE, adj. \_cryjlallinns , Lat.] Confiding 
of cryftal.—Mount eagle to my palace cryjlalline. Skahe- 
Jpearc.' —We provided ourfelves with Come fmall re¬ 
ceivers, blown of cryjlalline glafs. Boyle. —Bright; clear 
pellucid ; tranfparent. 
He on the wings of cherub rode fublime 
On the cryjlalline (ky, in faphir thron’d 
Illuftrious far and wide. Milton. 
CRYS'TALLINE Humour, in anatomy, a thick com¬ 
pact tranfparent matter, in form of a flattifh convex 
lens, placed in the middle of the eye, and ferving to 
make that refraction of the rays of light which is necef- 
fary to have them meet in the retina, and form an 
image there, by which vifion may be performed. See 
Anatomy, vol. i. p. 397. 
CRYS'TALLINE Heavens, in the old aftronomy, two 
orbs, imagined to lie between the primum mobile and 
the firmament, in the Ptolomaic fyftem, which luppof- 
ed the heavens folid, and only fufceptible of a (ingle 
motion. King Alphonfus of Arragon, it is (aid, intro¬ 
duced the cryftallines, to explain what they called the 
motion of trepidation, or titubation. The firft cryftalline,. 
according to Regiomontanus, &c. ferves to"account for 
the flow motion of the fixed (tars ; by which they ad¬ 
vance a degree in about feventy years, from weft to eaft ; 
which occafions a precefiion of the equinox. The fe- 
corid ferves to account for the motion of libration, or 
trepidation; by which the celeftial fphere librates from 
one pole towards the other, caufing a difference in the 
fun’s greateft declination. 
CRYSTALLIZATION,/ [from cryjlallize .] Con¬ 
gelation into cryftals ; the att or operation by which 
cryftals are formed. Such a combination of faline par¬ 
ticles as refembles the form of a cryftal, varioufly modi¬ 
fied, according to the nature and texture of the falts. 
The method is by dilfolving any faline body in water, 
and filtering it, to evaporate, till a film appear at the 
top, and then let it (land to (hoot; and this it does by 
that attractive force which is in all bodies, and parti¬ 
cularly in fait, by reafon of its folidity : v/hereby, when 
the menftruumor fluid, in which fuch particles flow, is- 
(ated enough or evaporated, fo that the faline panicles 
are within each other’s attractive powers, they draw onc^ 
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