XVIII. An Account of certam perfeEi minute 
Cryftal Stones^ by J. Parfons, M. D. & 
R R. S. 
Read June 27.*“ j' A H E Drawing here annexed, Tab. III. 
45 A f%. 1 o- reprefents a fmallCryftal mag- 
nified ; it is one of a -great Number brought by a very 
curious Gentleman from Gibraltar, who has caufed 
many of them to be fet in Buckles of different Kinds, 
for the Wear of his Lady and himfelf: And altho* 
they are formed and polilh’d by Nature ; yet they look 
very bright, and produce a very good Effeft in the 
Buckles. 
They were found accidentally. This Gentleman 
faw a Man cleaving a Rock near that Town, and 
obferv’d a great Quantity of fine black Powder fall 
from its Crevices and, being very curious, he ex- 
amined the Powder, and found thefe little Stones in 
Clufters, confiding of no more than twelve or four- 
teen each} and each Clutter lying at confiderable 
Pittances from one another. They are all of the 
fame Form, fome lefs perfect than others* and are in 
general Hexagonal*. 
XIX. A Letter from Mr . John Ellicot, 
R R . S. to the Prefid ent, concerning the 
fpecific Gravity of Diamonds. 
Read July 4. % s, from fome Experiments I have 
S 74S* XX lately had the Opportunity of make- 
ing, it appears highly probable, that what has for- 
merly 
