34 X)r. Eajon on Cryfiallization. 
tranfparency, &c. bear a ftrong analogy to thofc 
of the faline cryftals already defcribed. 
Each faline fubftance, of which there is a 
great variety, fhoots, as already obferved, into 
cryftals of a figure and degree of tranfparency 
peculiar to itfelf: and the fame thing is true, in 
general, with regard to gems or precious ftones. 
Thus, the diamond is naturally of one form, the 
ruby of another, the fapphire of a third, &c. and 
each of them poflefles a degree of tranfparency 
different from all the reft. 
Among philofophers it has long been a 
queftion, from what ftate the precious ftones 
have cryftallized ? that is, whether their particles 
were originally fufpended in water, or reduced 
to a fluid ftate by the adtion of a very intenfe 
heat ? Each of thefe opinions has been efpoufed 
by men of the firft abilities and reputation, and 
feveral arguments have been urged on both fides 
of the queftion. 
From analogy, and feveral fadls, which will 
afterwards appear, there is room, I am per- 
fuaded, to conjecture, that all precious ftones, 
with many other mineral bodies, have been 
originally in a ftate of fufionj- by means of heat, 
from which they have been formed by the law of 
cryfiallization. 
Pure verifiable earth, indeed, cannot be 
brought into fufion by the heat of our furnaces > 
but black flint has been melted without addi¬ 
tion 
