126 NATURAL HISTORY 
have as pure cryftals of the tabular kind ; we have quadrangular 
columns, and triangular pyramids, as pure, to all appearance, as 
any of the hexagonal kind whatfoever ; the caufe therefore of the 
hexagonal figure muft be lomewhat diftind from pure cryftal, fince 
we find that pure cryftal can fubfift without it, and is found as 
tranfparent, hard, and immoveable to acids in other figures as in 
that. It muft be alfo diftinct from the caufc of other figures ; for 
the fame principle which forms bodies into an hexagonal mafs, 
cannot be that which in other places give the trigonal or rhomboidal 
fhape to bodies of like fubftance. It is true, cryftals are oftener 
found hexagonal than in any other figure ; but this can prove only, 
that the caufe of this figure is more abundant than that which oc- 
cafions the other figures ; it will not prove, that it is infeparable 
from pure cryftal. Salt is the moft adive principle of the fofiil 
kingdom, every where difperfed, ever bufy, when fluid and at li- 
berty, in producing multangular figures, according to the feveral 
powers with which nature has invefted particular falts s ; and it muft 
be obferved, that there is hardly any figure in the cryftalline clafs 
but may be found in the analyfis of fome fait or other. Thus, for 
inftance, in nitre (a fait difperfed in earth and ftone, in air and 
water, in plant and animal, ) we find the exad reprefentations of 
hexagonal cryftals in their different ftates ', now with one pyramidal 
apex, as Plate XIII. Fig. x. now with two, as Fig. xi. fometimes 
with equal correfpondent fides, as Fig. x. fometimes with unequal, 
as Fig. viii. “ fome cut doping at the ends down to a fharp edge, 
in the manner of a chiflel,” (ib. page 62) as Fig. xrx- but always 
hexangular. In fal gevimcz , and fea-falt, we find the quadrangular 
pyramid, with the truncated ends, (ib. page 57) as Fig. xii. In 
the cryftals of alum we have the polygon, Fig. xxil. as well as in 
the falts of lavendar and thiftle, (ib. page 180). Among the cryftals 
of diftilled verdigreafe, (N°. vn. ib. Plate II. page 96) we have 
the columnar rhomboidal fhoot, Fig. xvill. In the falts of tin 
(page 128, ib.) we have the two pyramids applied bale to bale, as 
Fig. xiv. In Cheltenham falts (ib. page 154, Plate V.) we have 
the exa£t afterilk, as Fig. XXIX. The fait of Camomel has Fig. xx. 
(ib. page 166), and the parallel lifts of Fig. xxx. may be feen 
there and in the falts of fennel, (page 172), and in the lalt of 
thiftle, (page ib. 180.) The fait of the Jefuit’s bark is full of 
rhomboides. In the fal getnmce (letter <?, ib. pa. 74) is that lump of 
pyramidal cunoeids placed laterally as in the cryftal, Fig. xxxv. 
The pentagonal tabulated cryftal is found alfo in the falts of camo- 
* This has made fome Naturalifts advance that 
omnis cryftallizatio eft a fale. “ Salia cryftalli- 
aationis omnis unica caufa.” Linnaeus Syft. Nat. 
page 224. 
' See employment for the microfcope, by Henry 
Baker, Efq; F. R. S. vol. II. page 65. 
mel, 
