• ° ? f R m m
fonje* ^rc'v yqllow, ; brown,1 g^wA , ,:opaÉe^whjite,A* gteen, purple,
blacK, ' f b m e f ^ M ^ ^ ^ | | | S ^ ^ ^ ^ | | | ^ ^ ^ 3^jés,,and-rnag^
glides-, ® ty Gjyft^l filing eit^eïj|^ûfev and pellucid^ qÈ receiving its
lihge-ffom the mineral f||iees and elkhsgdjkcdnti Thiefe ftopes, it is
■ $|f§iyable, a'r^ggperally^^^^dl^andt-’tr-^paxerit: a f ! tfiie ;ppint
than ai|V>hè<rÔot& have Bâd tyc^pnples ’©fOiyf^alMne c u [p m ^ & x -
tirè|y¥fe|g.ck,, ancÇj|®aJe;ifeèn |ri| mpre, they filing-very;rqre. This
Tort*is(M|cen no|ie^ )of ^by Linnæu||Syft-. Nat.- pâge{TÔ yj \ap,d is, J
think,f his N itr ffm w ^ m f%ofum [ nm è^m . or- Morion ’ .
®T|he mote clear jf^è-ylare, the heavier; hfijwhielf the reaTan, fefrfrW s E CT. vn_
to be, JjaHn cifar^one^thérms more ftdne (in tany ‘given quantity/height*
■ '$$$\ in Opak^^fa^s,',;^lüph|la^qr> confiftipg of ,^gthy;an4\miaeral
^purities mixe^f yykjhjthe ’ftbny; muft ! thfrâdre under, any 4equal
furface inchide^p§ftftop.e thanvthe purer ,qriés,. ,;and| tftrs ^bfér^âfion
isOofifirmed by th© funerior weight of.thp true diamond to Slafiff
other ftones. The,-Weight of our Çdrnifh diamonds to water, I find
at a medium, .asTcp. and a .half is tofpiiF. f $
^ T h e .fame reafon that ^makes the pure more heavy than thofp SEC^yiir.
which^^jg other.wife, makes them!alfo harder; the moredfepyfimi-Hardnef"s-
lar matter there is,‘ the eldfer is the connexion of parts; whereas
g-he çqhè$ibn is'cgrèàîtly weakened, anti the body-becomes; tn^r^ frif
•^.jale by means of the j earthy parts which intrude', themfelves among
the;>ftonÿvî A e clearer itfierefore our Cornifh cryftals aip;,^the better
•their-fpointjs will cut gjafs (though not fo free, or fo deep as ;the true
diamonds) and the better they Will bear engraving for fèaîs,
Ip The^textùre of tfiefe figur’d cryftals is various ; ;fome are of an sbct. rx.
uniform texture, of one. colour and confiftcnce throughout : this 1
Was the-cafe of Fig. v. vi. xxtv. and many others hère exhibited.
|§pme fpring as from a center^ or qn,e common line, ds Fig.-v. vi.
y ii. xxxiis1; fome? have hexagonal fheaths< .defcribed One'within
,|ânother, as Fig. x x x ., apvery, reniarkable- ftru^tûre, and not: eafily
accounted for ; fomé) learned men imagine that they are different ,
„incruftations, applied fucceflively at different times, one ' without
the1 other, and fii'ch indeed at firft flight, they feem to be, but i f We
recur to the original formation!.; qfvthefe hodies'-(|as^in;order,td'discover
truth we muff).it will be 'vçry difficult,-not to-fay impoflible,
for us to conceive àny pofition OrMireCtion in which the-tn&ddlemoft
fhaft could lie, fo as that thre^ incruftations .ôf fùch an equahthiek-
nefs fhould form round it, neither will the laws of gravitation and
(i Viie Morionr
projection