Formation of Crystals m Geodes. 285 
matter had concreted into well characterized mammillary 
chalcedony. ) | pe 
Although we have to regret, that the fluid escaped ex- 
amination, we submit the following conclusions as flowing 
from the facts which have been stated. 
Ist. The cavities have been occupied by a fluid hold- 
ing silex in solution. 
_ Qdly. ‘This silex has been in some cases deposited, in 
the form of quartz crystals, transparent and perfect, and 
this may be presumed to have happened in the course of 
a long time. py sie 
3dly. Where the crystallization has been rapid, the 
crystals have been more opaque and dull, and also longer. 
and more slender. : 
4thly. Under different circumstances, probably where 
the evaporation was more rapid, the silex has assumed the 
appearance of a dried precipitate mixed, in some cases, 
with imperfect crystals. ! 
 Sthly. Itis at present quite impossible to say what fluid 
forms the solvent, or what imparts to it its extraordinary 
powers, nor is it easy to say, what is become of the Suid, 
in the cavities which are dry and lined with the spongy 
silicious deposit, or with crystals more or less perfect, or 
with chalcedony. 
In enquiring for parallel cases, we are not able to recol- 
lect more than two. We do not consider as parallel the 
drops of transparent water, or possibly other fluids, occa- 
sionally found in rock crystals, or other stones, nor do we 
consider the microscopic fluids of Dr. Brewster as of this 
class. It is possible that they may prove to be so, but cir- 
cumstances do not at present appear to justify this concly- 
sion. 
Of the two facts, just now alluded to, one is derived from 
ihe oral statement of Eli Whitney, Esq. of this city, and 
the other is found in the writings of Count Bournon. 
Mr. Whitney states, that being in Georgia, in the year 
1806, he was informed of the following facts, and saw the 
specimens by which they were established. OnBriercreek, 
a stream which passes through Millhaven, and empties 
into the Savannah ‘ver, and at the distance of two 
or three miles from the road leading from Savan- 
nah to Augusta, the people were occupied in excava- 
ting a raceway fer a mill; the mill dam was built 
