[ 2 7i ] ' 
to, cannot be fo eafily determined. Some think to 
Percolation, or (training through the Pores of other 
Codies, the lapidcous Juice depofiting the Sediment 
and Impurities, which it may have contracted in its 
PafTage. Now, it is not impodible but that the Water, 
and that liquid Spar, of which thefe Bodies are prin- 
cipally formed, palling by their own Weight thro’ a 
fofr, porous, fandy Stone in the Oxford , Bath , and 
other-like Quarries, may undergo a Change for the 
better, and acquire a greater Degree of Tranfparency ; 
but it cannot be fo with our Spar, on which we find 
the Cryftals above mentioned : For, befidcs that thefe 
Cryflals are found on both Sides the Stone (22) 
(which, in the Procedure of Percolation, could never 
happen), and in very large Shoots, our Spar will no 
more tranfpire or exude than Glafs, it is of fuch Con- 
fiftency and Hardnefs : So that whatever Filtration 
has happened to thefe Cryflals, mufl have befallen 
them during a former Percolation, before they refled 
in their prefent 'Beds, not from any fweating thro’ 
that Bed in which we find them, as Dr. ‘Plot ima- 
gines- (23). 
Cryflals therefore, it is certain, owe their Tranf- 
parency and Purity to the iimple State of the Juices 
that form them ; but to what that State and Condi- 
tion is owing is uncertain. Whether it may be to fome 
purifying Mcnftruum or Spirit, that precipitates every 
kind of Sediment, I do not prefume to fay: I (hall 
only obferve, that in Cornwall the cleared Diamonds 
are for the mod part found in a dry, lax, fandy Soil, 
where 
(22) See Fig. 8. Tab. IV. * 
(23) Oxford])), p. 98. zn^Ramundus in Alonzo Bar ba> p 3 6. 
