( 273 ) 
The Author divides this prefent EiTay into two Parts, 
viz. a ftiort Commentary upon the Cryft alios , as he calls 
them, tmproprie fic dittos^ in the firit ; and an Account 
of fuch as he found mentioned in feveral Authors, with 
a Redudion of them under certain Heads, in the fecond. 
Cryftalli imjprofrie fic ditti^ according to the Au- 
thor's Definition, are fuch Bodies, either Stones, Metals, 
or Salts, as have any Refemblance with the true Cry- 
ftal either, as to their multangular, regular, or irre- 
gular Figure, or as to their Pellucidity, or any other 
of its effential Properties. As the Number of thefe 
Bodies is very extenfive, fo an exad Enquiry into them 
cannot but be both ufeful and agreeable. I juft now 
obferved, that the Cryfialli improprie fic ditti are 
taken out of Stones, Metals, and Salts. To the firft 
belong amongft otherThings fuch precious Stones, as, in 
all Probability, have their certain, determined Cryftal 
like Figures, as Diamonds, Amethyfts, &c. To the fe- 
cond belong all Sorts of *Pyrita, as alfo the Growth of 
Silver, and other Metals, in Form of Trees, or other 
Things. By the third are underftood all Chyrnical Pre- 
parations of Salts, and faline Bodies, the Figure of 
which is, generally fpeaking, more accurate, than in any 
of the two former. Several Authors of Note have en- 
deavour’d to explain how, Cryftallifation is perform’d, 
or how it comes, that certain Subftances fhoot into 
Cryftals. Dr. Capfeler mentions the Hypothefis of 
the learned Gulielminus , and that of a late Swedifb 
Author, Swedenbergh ; and though he feems more to 
favour the latter, than he doth the former ; yet he 
thinks, that they are both liable to Exceptions. But 
whatever the Caufe or Method of Cryftallifation be, 
our Author takes it for granted, that three Things are 
abfolutely requir’d for it, viz. Salt 7 which muft al- 
d q 2, ways 
