Formation of Crystals in Geodes. 287 
they rivalled both in perfection of form, and in transpar- 
ency. Count Bournon caused numbers of these geodes to 
be broken ; some of them were full of water; ona partic- 
ular occasion a happy fracture left half of one of these 
geodes, containing unspilt the liquor which it had enclosed. 
Perceiving that the fluid moved heavily, in a kind of mass, 
(almost like mercury,) he concluded that it must be a very 
concentrated solution, and as it was in the middle of a very 
warm day in the month of July, the fluid was all evapo- 
rated, in little more than a quarter of an hour, and there 
remained in the geode, a spongy amorphous crystalline 
mass of carbonate of lime. This fact is certainly very 
instructive as to the formation of crystals in geodes. Count 
Bournon observed the same thing at Vougy, about the 
same period, but the geodes were composed of black oxide 
of manganese lined with crystals of carbonate of lime. 
If the above facts should appear to others as they do to 
us, worthy of being preserved, we hope that all similar 
facts which our readers may be acquainted with, will be 
communicated to the public. They may throw important 
light upon certain occult natural processes. 
P. S. Since the above was written the following par- 
agraph has been observed in the 15th number of the Edin- 
burgh Philosophical Journal. 
“© On the Formation of Rock-Crystal, 
Spallanzani remarks that the numerous beautiful rock- 
crystals in the cavities of the Carrara marble, continue 
still to form, and from a pure acid fluid. Ripetti in his 
tract ‘ Sopra |’Alpe Apuana ei Marmi di Carrara, 1811,” 
adduces some new observations in favour of this opinion, 
and tells us, that on opening a drusy cavity, there was 
found 14 lb. of the above fluid, and among the solid crys- 
tals, a soft. mass the size of the fist, which, on exposure to 
the air, hardened into a substance having the characters of 
calcedony. According te Daubuisson and Beaudant, the 
opal of Hungary is sometimes found in a soft state.” 
